Mahindra & Mahindra Ltd Truck and Bus Division Study Material PDF

Mahindra & Mahindra Ltd Truck and Bus Division Mahindra Truck and Bus Division ‘Extramile’ –Pune Study Material – ILCV “Kaun Banega Ustadon Ka Ustad” – Season 7 Round – 2 1  Mahindra & Mahindra Ltd...

Mahindra & Mahindra Ltd Truck and Bus Division Mahindra Truck and Bus Division ‘Extramile’ –Pune Study Material – ILCV “Kaun Banega Ustadon Ka Ustad” – Season 7 Round – 2 1  Mahindra & Mahindra Ltd Truck and Bus Division Measuring Instruments: Vernier Caliper: Sample Reading: 2  Mahindra & Mahindra Ltd Truck and Bus Division Micrometer Sample Reading: 3  Mahindra & Mahindra Ltd Truck and Bus Division Dial Gauge: Sample Reading: 4 Mahindra & Mahindra Ltd Truck and Bus Division LCV Vehicle Model Matrix BSVI Without Air Compressor With Air Compressor 5  Mahindra & Mahindra Ltd Truck and Bus Division Aggregate Matrix Air Intake System Air Filter element needs to be cleaned in every service and whenever clog indicator shows red band. Air filter element needs to be replaced as per the service schedule If the vehicle is used in severe dust conditions air filter needs to be replaced more frequently based on condition of the filter Clean the air cleaner using compressed air with pressure less than 1.5bar from inside to outside. Single Element Double Element Single Air filter element is available with Double element is available with 3.3L, 2.5L, 2.6L, and D25 engine D35 DS & D35 Engines 6  Mahindra & Mahindra Ltd Truck and Bus Division Air filter Clogging Indicator: Mechanical Type Electrical Type Whenever the air filter is choked, the red band in the service clogging indicator or cluster is visible. The filter must be cleaned with compressed air of less than1.5 bar pressure from inside the air cleaner towards outside. After cleaning the air filter element & fitment, the black knob in the Mechanical clogging indicator should be pressed upon to release the red band. Turbo Charger: Waste gate type Turbocharger – Waste gate type Turbocharger – Mechanically operated Electrically operated by ECU Available in all LCV BSIII and BSIV Available in all LCV BSVI models models 7  Mahindra & Mahindra Ltd Truck and Bus Division Fuel System: NEF BSIII & BSIV (BOSCH) MDI BSIII & BSIV (DELPHI) 8  Mahindra & Mahindra Ltd Truck and Bus Division D25 & D35 DS (BOSCH) Note: IMV location is on HP pump in D25 engine and above starter motor on block in D35 DS engine Lubrication System: MDI BSIII, BSIV and D25 For getting proper oil pressure always needs to be checked at hot condition of Engine. 9  Mahindra & Mahindra Ltd Truck and Bus Division Exhaust System: BSIII Engines - BSIV engines are fitted with EGR system which is getting actuated by Vacuum. Vacuum, connection is taken from Vacuum pump which is available behind of alternator. BSIV - BSVI engines are fitted with EGR which is actuated by ECU electronically. There is no vacuum requirement because of this reason Vacuum pump is deleted from alternator. There is no EGR cooler for D25 engine, but coolant circulation is available for EGR body. 10  Mahindra & Mahindra Ltd Truck and Bus Division OBDI OBDI D25 & D35 DS OBDII PM Sensor DNOx 3.3 11  Mahindra & Mahindra Ltd Truck and Bus Division NEF Tappet Setting: The procedure for Tappet clearance setting is as follows. 1) The tappet setting should be done in engine cold condition. 2) Bring no.1 piston to compression TDC point. The compression TDC point is identified by the position of Rocker arm levers (both push rods will be free). 3) Adjust the tappet clearance of No. 1 valves as per the given specifications. 4) Rotate the crankshaft by 180° to bring no.3 piston to compression TDC point and set the tappet clearance. 5) Repeat the same for piston no. 4 & 2 by rotating crankshaft by 180° each time. Note: The above said tappet setting procedure is same for all NEF engines (BS II & BS III). F R O N Valve layout: T Ex1 – In1 Ex2 – In2 Ex3 – In3 Ex4 – In4 The Tappet clearances for valves for NEF BSIII & BSIV engine is as follows Inlet valve : 0.45 mm (18 Thou) Exhaust valve : 0.45 mm (18 Thou) MDI / D25 Tappet Setting: 1) Set the 1st piston at compression TDC by aligning main pulley TDC mark & the TDC pointer. 2) Do the tappet setting for In1, Ex1, In2 & Ex3 3) Rotate the Crank shaft by 360° to bring the 4th piston in compression TDC. 4) Do the tappet setting for In4, Ex4, In3 & Ex2 The Tappet clearance value for MDI BSIII, BSIV & D25 engine is Inlet valve : 0.40 mm (16 Thou) Exhaust Valve : 0.50 mm (20 Thou) VALVE LAYOUT : In1–Ex1 Ex2 – In2 In3 – Ex3 Ex4–In4 While assembling the rocker shaft, The lubrication holes needs to be face towards cylinder head side. Else oil will get throw from breather. There is no Valve clearance adjustment process in D35 engine because there is hydraulic lash adjusters available and gap automatically get adjust due to Hydraulic pressure. 12  Mahindra & Mahindra Ltd Truck and Bus Division Engine Timing: GEAR TIMING PROCEDURE – MDI BSIII & BSIV, D25 MDI engine has gear type timing mechanism. The alignments of the gears are as follows. 1) Before setting the timing, the 1st Piston should be in compression TDC, so that the Crankshaft key position is in 3’O clock position. 2) Match the single dot of Crank gear to the single dot of Cam gear. 3) Match the double dot of Idler gear to the double dot of Crank gear 4) Match the singe dot of Idler gear in between the two dots of FIP gear CHAIN TIMING PROCEDURE – NEF BSIII & BSIV 1) The key way of crankshaft sprocket should be in 12’o clock position 2) The Chain has 49 links out of which only 2 links have black marks. 3) The link having black mark should be matched with single dot in the crank sprocket & other link having black mark should be matched with the single dot in the Cam sprocket. 13  Mahindra & Mahindra Ltd Truck and Bus Division 4) The distance between the cranks & cam sprockets should be 14 links. (This is the 14th link from the crank sprocket’s unmarked link which is between the two marked links). GEAR TIMING PROCEDURE – D35 DS & D35 Procedure: 1) Before setting the timing, bring the 1st cylinder Piston in compression TDC, in that position the Crankshaft key will be in 12’O clock position. 2) Match the single dot of Crank gear with double dot of Cam gear. 3) Match the single dot of Idler gear in between the double dot of Crank gear. 4) Match the single dot of Air compressor gear with double dot of Idler. 14  Mahindra & Mahindra Ltd Truck and Bus Division Clutch All MTB LCV Vehicles are having the following Clutch system. - Diaphragm type - Single plate - Hydraulic - Dry type - Push Type Model Clutch Plate (mm) Pressure Plate Type-of actuation (mm) 2.5L BSIII, BSIV, 2.6L BSIII 240 242 Hydraulic 3.3L BSIII & BSIV 280 281 Hydraulic D25 260 – JAYO 261 Vacuum assisted Hydraulic 280 – Remaining all D35 DS 310 311 Vacuum assisted Hydraulic Clutch Bleeding: When ever air is entered into system clutch pedal becomes spongy and need to go for following process 1) Insert the hose on the bleeding screw and keep the other end in a clutch fluid container. 2) Now, pump the clutch pedal several times & keep the pedal pressed and loosen the bleeding screw on the Clutch slave cylinder. 3) If any air is present, air bubbles are visible on the bleeding hose. 4) Tighten the bleeding screw. 5) Repeat the procedure till all the air from the system is bled (Note: Do not use the fluid in the container to top up) 15  Mahindra & Mahindra Ltd Truck and Bus Division Clutch Free Pedal Play: DI 3200 BSIII & T-15 BSIII & T-25 & LK BSIII & T-32 / 40 BSIII & T-15 BSII BSIV BSIV BSIV BSIV Clutch pedal free 1.0 - 5.0 mm 5 to 7 mm 1.0 - 5.0 mm 1.0 to 5.0 mm 5-7 mm play Clutch pedal 155 - 160 mm 184 mm 155 - 160 mm 155 to 160 mm 184 mm height Clutch Fluid Grade, Quantity & Change Interval: DI 3200 BSIII & T-15 BSIII & BSIV T-25 & LK BSIII & BSIV T-32 / 40 BSIII & BSIV BSIV Oil Grade DOT4 DOT4 DOT4 DOT4 Quantity 370 ml 370 ml 370 ml 300 ml Change At every 40000 At every 40000 Kms At every 40000 Kms At every 40000 Kms Interval Kms 16  Mahindra & Mahindra Ltd Truck and Bus Division Transmission: BD 30 Gearbox is a Five speed Gearbox MNT40 Gearbox is a Five speed Gearbox Five Forward gears – Synchro mesh gears Five Forward gears – Synchro mesh gears Reverse Gear – Sliding mesh gear Reverse Gear – Constant mesh gear Engine Model Gearbox MDI BSIII & BSIV BD30 NEF 2.6L BSIII BD30 – LK PRIDE, SUPER, 25,29-SEATER & MNT40- ZOOM & OPTIMO NEF 3.3L BSIII & BSIV MNT40 D25 BD30 – JAYO, MNT40 – REMAINING ALL D35 DS MNT40 For BSIII and BSIV models the gear cable standouts are mentioned Select & Shift Cable Standout values: BD30 SNO Description DI 3200, LK, T-25, T-15 BSIII (mm) 1 Shift cable Standout at gear lever end 184 +/- 2 2 Selector cable Standout at gear lever end 120 +/- 2 3 Shift Cable Standout at gearbox end 188 +/- 2 4 Selector Cable Standout at gearbox end 125 +/- 2 17  Mahindra & Mahindra Ltd Truck and Bus Division Shift Cable - Yellow colour Selector Cable - Blue Colour The ends of the cable cannot be interchanged. The color codes are available. Select & Shift Cable Standout values: MNT40 S.NO DESCRIPTION LK Zoom & T32, T-40 1 Shift Cable length at Gear lever end 184 mm 2 Selector Cable length at Gear lever end 120 mm 3 Shift Cable length at Gear box end 153 mm 4 Selector Cable length at Gear box end 178 mm Rear Axle: Model Differential type Ratio Backlash 2.5L DANA 5.13 0.125 TO 0.25 mm 2.6L MERITOR 6.14 / 6.20 0.20 TO 0.46 mm 3.3L American Axle (AAM) T-32 = 5.13 & T-36/40/42 = 6.33 0.18 to 0.31 mm 18  Mahindra & Mahindra Ltd Truck and Bus Division BSVI VEHICLES Vendor Ratio Backlash Run out & Face out CRUZIO 15 5.10:1 – 15-Seater DANA 0.10 to 0.18 mm CRUZIO 20 5.29:1 – 20-Seater CRUZIO 25 MERITOR 6.14:1 0.20 to 0.46 mm CRUZIO 29 CRUZIO 32 5.12:1 Less than 0.20 mm CRUZIO 36 AAM 0.18 to 0.31 mm 6.33:1 CRUZIO 40 JAYO DANA 5.125 0.125 TO 0.25 mm FURIO 7 4-TYRE MERITOR 5.83:1 0.20 TO 0.46 mm FURIO 7 6-TYRE MERITOR 5.29:1 Crown Wheel – Pinion: Identification (Dana & Meritor) 1. PART NUMBER 2. NO. OF TEETH ON CROWN WHEEL 3. MANUFACTURING NUMBERS 4. MATCHING GEAR SET NUMBERS 5. NO. OF TEETH ON PINION 6. DATE CODES 7. INDICATES GENUINE SPICER PARTS 8. HEAT CODE 19  Mahindra & Mahindra Ltd Truck and Bus Division Crown Wheel – Pinion: Identification (American Axle Manufacturers - AAM) 1 – Part Number 2 – Set Number 3 – Charge Number 4 – Ratio 5 – Depth Setting 20  Mahindra & Mahindra Ltd Truck and Bus Division Crown Wheel & Pinion Nomenclature: A – Top: The top of the gear tooth B – Root / Flank: The bottom of the gear tooth C – Heel: The outside diameter end of the gear tooth D – Toe: The inside diameter end of the gear tooth E – Drive: The convex side of the gear tooth F – Coast: The concave side of the gear tooth 21  Mahindra & Mahindra Ltd Truck and Bus Division A – Head B – Inner Bearing Seat C – Shaft D – Shoulder E – Outer Bearing Seat F – Splines G – Threads Note: Before dismantling the differential, inspect the following as per the complaint & symptom: 1. Differential Oil – Quantity, Quality, Presence of any metal / foreign particles 2. Crown Wheel Run Out 3. Crown Wheel Face Out 4. Crown Pinion Backlash 5. Check for free rotation of Crown Wheel 6. Pinion Bearing Pre-Load Note down the above readings wherever measurable & if they are withing specification, then it is better to set at the same values in Crown wheel & Pinion during assembly. If a new Crown Pinion assembly is used, then refer the following table to understand the specifications. Note: 1. The Crown & Pinion are a pair & needs to be replaced together as a unit. 2. The Value of Pinion Mounting Depth (PMD) on Crown wheel will be punched on the Pinion face. 3. The PMD value in Dana & Meritor is given in “Thou” & in “mm” in American Axle 4. For identification of Crown Pinion assembly as a unit, matching gear set numbers are given on both Crown Wheel & Pinion. Crown Pinion Tooth Contact Pattern: Proper tooth contact pattern can be achieved by accurately controlling 2 variables. 1. Pinion Mounting Depth (PMD) 2. Crown Pinion Backlash Tooth contact (mesh) must be carefully controlled so that tooth contact stress is spread out and not localized, otherwise surface damage to the teeth, tooth breakage, and noisy operation will result. This 22  Mahindra & Mahindra Ltd Truck and Bus Division means using only matched ring and pinion sets and accurately setting backlash and pinion depth. To put it in a sentence, it can be said that if pinion mounting depth & Crown Pinion Backlash are properly set as per specification, then the contact pattern is automatically achieved. Rectification in case of deviated contact pattern: 23  Mahindra & Mahindra Ltd Truck and Bus Division Note that any changes made in PMD setting or Backlash will affect the other i.e: 1. If the PMD setting is changed, then consequently the backlash will also be affected. 2. If the Backlash setting is changed, then consequently the PMD will also be affected. Therefore, whenever any of these 2 parameters i.e Backlash & PMD settings are changed, contact pattern needs to be verified after the changes for confirmation. 24  Mahindra & Mahindra Ltd Truck and Bus Division Brakes: VAHB With ABS - JAYO, 15,20,25,29, Load king, FURIO 7 4-Tyre and 6-Tyre, Optimo are fitted with VAHB (Vacuum assisted Hydraulic Brake) Load Conscious Regulating Valve: LCRV controls the brake fluid flow to the rear brakes during vehicle unloaded condition, thereby preventing the rear wheels getting locked and insufficient brake at rear wheels in loaded condition. Gap to be set 25  Mahindra & Mahindra Ltd Truck and Bus Division Gap setting procedure: 1) The piston end of LCRV has to be fitted to the chassis and the other end to the rear axle. 2) Mount the other end of LCRV on the lower hole of the strap on rear axle. 3) Now, set the gap between the bolt & the piston end as shown in the figure. 4) The gap value is given in Brakes specification chart for different models. 5) After setting the gap, remove the other end of the LCRV from the lower hole of the strap & fit it on the upper hole of the strap. MODEL LCRV GAP JAYO 2.80 mm OPTIMO, FURIO7 3.50 mm Brake Adjustment Process - VAHB Jack up the vehicle, until the wheels clear off the ground. Remove the rubber grommet from the backside of the back plate. By inserting a Special tool (Brake adjuster - TVS) through the adjuster hole, lock the brake drum by rotating the adjuster wheel. An arrow mark is stamped on the back plate near the slot to indicate the direction for adjustment. Then loosen the adjuster wheel up to 6 to 8 notches until the wheel rotates free. Check the gap between liners & drum, it should be 0.25 mm. Rotate the drum and check for the same. Keep the engine on to get servo assistance. Apply the brakes 2 or 3 times simultaneously rotating the wheel to allow the shoe to centralize in the drum. Readjust, if necessary, until the wheel can just be freely rotated. Fit back the rubber grommet on the back plate slot. Repeat this procedure for the other shoe. 26  Mahindra & Mahindra Ltd Truck and Bus Division Pneumatic Brakes: - 32, 36,40,42,55 BSIV models and 32,40 BSVI models fitted with Pneumatic Brake system - Brake System Pressure: 8 Bar - Relay valve is not present in 32-seater. Relay valve is given for rear wheels braking purpose. 27  Mahindra & Mahindra Ltd Truck and Bus Division ICV Engine - D35 Rocker Assembly Rocker arms are mounted on rocker shafts which are in-turn supported through rocker beds mounted on the cylinder head. Ensure that the holes in the Rocker arm shaft face the cylinder head side (downside) while fitting. 28  Mahindra & Mahindra Ltd Truck and Bus Division Direction of rocker shaft assembly The length of the rocker arm on both sides from its mounting points in the bed are different. The rocker shaft long end (from mounting) is towards flywheel side and short end is towards fan side. When assembling the rocker, it is to be noted that on either ends of the rocker shafts circlips need to be fitted and on either side of the springs, washer’s needs to be added for uniform contact. The rocker arms are also easily identifiable with markings on them. I – Indicates intake rocker arm and E – Indicates exhaust rocker arm. Rocker arm shaft tightening Sequence: Valve layout F R O Valve layout: N Ex1 – In1 Ex2 – In2 Ex3 – In3 Ex4 – In4 DI 3.5L engine is equipped with hydraulic lash adjuster, which is a device for maintaining zero valve clearance by the hydraulic pressure. Hence, this engine does not require to do tappet setting. Rocker arms are not serviceable. 29  Mahindra & Mahindra Ltd Truck and Bus Division Belt Layout Belt Driven: Power Steering Pump + Alternator + Water Pump Gear Driven: Crank + Cam + Oil Pump + Air Compressor (H.P Pump Driven by the Air Compressor) 30  Mahindra & Mahindra Ltd Truck and Bus Division Belt Tension Checking This engine is equipped with an auto tensioner hence belt tensioning not require. Air Intake System Air Intake System Layout 31  Mahindra & Mahindra Ltd Truck and Bus Division Air Cleaner Assembly There are two elements in the Air cleaner Assembly – Air Cleaner Element Safety Element The pore size of the element is optimized to hold the finest of dust particles in the air being supplied to the engine. Change Frequency The Primary air filter element change interval is *40,000 Kms or when the air filter clog Indicator glows in the dashboard. (*The filter life & the change frequency depend on the conditions under which the vehicle is used. In the dusty conditions the air filter may have to be replaced earlier than the mileage stated above.) Cleaning of air filter element / safety element with compressed air or by any other means is not recommended. At Every third change of Primary air cleaner element; the Safety Element should be changed. Air Cleaner restriction / Clog indicator Air filter clog / restriction indicator is located in the Instrument cluster & is electrically operated. As the air filter will get choked, signal can be seen on Cluster. After replacing the air filter, we need to reset the signal by using manual switch given near to the air cleaner filter. 32  Mahindra & Mahindra Ltd Truck and Bus Division Fuel System Fuel Routing Suction Line 1. Fuel Tank 2. Fuel Float Unit (with Strainer, Suction Line & Level sensor) 3. Fuel Filter Assy (Water Separator & Fuel Filter) 4. High Pressure Pump (CB18) 5. Common Rail 6. Fuel Injectors Return Line 7. From Fuel Injector & PRV on Common Rail 8. From High Pressure Pump 9. Common Return Line to Tank 33  Mahindra & Mahindra Ltd Truck and Bus Division Fuel Flow Diagram Tightening Torque Sl Tightening Torque Description Fastener Type No (Nm) 1 H.P Pump fuel inlet from fuel filter assembly M14X1.5 20 +/-2 2 H.P Pump fuel return to fuel tank M10X1 20 +/-2 3 H.P Pump fuel outlet to common rail M14X1.5 30 +/-5 H.P Pump fixing Screw (Pump Mounting on Air 4 M8X1.25 22 +/-3 Compressor Interface Housing) 5 Air Compressor Interface Housing Mounting M8X1.25 22 +/-3 6 Bleed Screw M6X1 8 +/-2 34  Mahindra & Mahindra Ltd Truck and Bus Division Fuel Filter Replacement The Water Separator Come Fuel Filter is mounted on the chassis frame near the fuel tank. The Change Interval of both the Fuel Filters are at every 40,000 Kms. Fuel Tank Fuel tank is mounted on RH side of chassis Alusi Coated. It is available in 2 capacities 160 L & 190 L. Bosch High Pressure Pump CB18 35  Mahindra & Mahindra Ltd Truck and Bus Division Process of Air Bleeding from Fuel System: 1. Park the vehicle on a level surface & ensure sufficient quantity of fuel is available in the fuel tank. 2. Start priming the hand pump & then loosen the bleed screw present on the outlet of fuel filter assembly. 3. Continue priming on water separator until clear fuel comes out of air bleed screw without any air bubble. 4. Tighten the air bleed screw on water separator head. 5. Now loosen the hex screw of 10 mm on the CB18 High Pressure Pump. 6. Start priming using hand primer on water separator until fuel comes out of air bleeding screw from CB18 High Pressure Pump without any air bubble. 7. Tighten the hex screw of 10 mm on CB18 High Pressure Pump. 8. Continue priming till the primer becomes hard. 9. The fuel lines in the low-pressure circuit should now be sufficiently filled with fuel & engine should start on a long crank. Keep priming & cranking till the vehicle starts. Keep the engine running in low idle for a few minutes to completely remove the trapped air, if any, from the low-pressure circuit. Note: Do not try to remove the air from the fuel system by cranking only. It will result in dry run of the high- pressure pump resulting in wear & tear of pump’s internal components. 36  Mahindra & Mahindra Ltd Truck and Bus Division Fuel Tank Neck & Combination Unit Combination unit is of Reed Switch type (Similar to HCV). But the lengths are different due to change in tank design. Fuel Filter Installation Lubricate the ‘O’ ring. Install the fuel filter and rotate is by ¾ (270°). Water Drain from Filter Remove the drain plug, now drain the water from filter. Don’t use spanner to open & tighten the plug. 37 Mahindra & Mahindra Ltd Truck and Bus Division Lubrication System 38  Mahindra & Mahindra Ltd Truck and Bus Division Servicing Points The servicing jobs involved in Lubrication system are as below – Oil level Check. Oil & Oil Filter Replacement External Oil leakage check Some common Problems observed in lubrication System – External Oil leak from joints / gaskets Cooling System Cooling System Layout 39  Mahindra & Mahindra Ltd Truck and Bus Division Radiator Pressure Cap The pressure cap in the radiator helps in avoiding any loss of the coolant. The radiator cap controls the system pressure to 0.9 bar above atmospheric. If the pressure exceeds 0.9 bar above atmospheric, then the pressure cap lifts up & the coolant goes to the coolant reservoir tank/no loss tank. Radiator Pressure Cap When the system pressure falls, vacuum gets created and the vacuum valve opens up. The coolant from the no loss tank flows back into the radiator, thereby minimizing loss of the coolant. Thermostat The thermostat maintains the optimum engine running temperature by cooling the hot coolant whenever necessary. Start open Temp – 68 to 72 deg ˚C Full open Temp in – 84 deg ˚C Travel at Full open temp – 7.5 mm Viscous Fan Drive (VFD) The Viscous fan drive operates at different temperatures of air temperature at the Thermo couple ring. Fan Diameter – 430 mm Fan engagement starts – 72 deg ˚C Fan full engagement – 78 deg ˚C 40  Mahindra & Mahindra Ltd Truck and Bus Division Check before testing viscous fan operation. Check the coolant level. Check the temperature gauge. Check that radiator fins are free from dirt’s and insects. Check the proper operation of the thermostat valve. Check the operation of the water pump. Check if sufficient hot air can flow through the radiator to activate the fan clutch. Check the blockages inside the radiator preventing flow of coolant. Check that the fan blade is not damaged. Noise generated by the AC clutch or by the engine should be investigated. If all these checks are satisfactory then preliminary checkups for viscous clutch and fan to be carried out Note: This test must be conducted after the vehicle has been off for extended period of overnight or in cold condition. Exhaust System Muffler is installed on the engine to reduce exhaust noise. Muffler consists of resonating chamber, where opposite sound waves cancel each other. BS III BS IV Exhaust System layout Exhaust Valve Exhaust Valve Exhaust Manifold Exhaust Manifold Exhaust Gas Recirculation (EGR) Turbocharger Turbocharger Exhaust Brake Exhaust Brake Muffler Disel Oxidation Catalyst (DOC) After Treatment Devices Particulate Oxidation Catalyst (POC) Muffler 41  Mahindra & Mahindra Ltd Truck and Bus Division DOC (Diesel Oxidation Catalyst) DOC consists of a stainless-steel canister that contains a honeycomb structure called a substrate. The interior surface is coated with catalytic metals that oxidizes the CO & HC converts into carbon dioxide (CO2) and water (H2O). POC (Particulate Oxidation Catalyst) Particle oxidation catalyst (POC) is device that can capture and store PM material for a period of time sufficient for its catalytic oxidation, while having open flow-through passages that allow exhaust gases to flow, the POC is a specialized diesel oxidation catalyst with a capacity to hold solid soot particles. The captured particles are removed from the device through the process known as Passive Regeneration, it doesn’t require cleaning or external heating. Exhaust Gas Recirculation (EGR) EGR reduces the nitrogen oxide (NOx) emissions by recirculating some amount of engine's exhaust gas back to the engine cylinders. This dilutes the O2 in the incoming air stream and provides gases inert to combustion to act as absorbents of combustion heat to reduce peak in-cylinder temperatures. Thus, EGR reduces the amount of NOx in exhaust gases. 42  Mahindra & Mahindra Ltd Truck and Bus Division Exploded View 43  Mahindra & Mahindra Ltd Truck and Bus Division To meet the Emission standards, for ICV Engine has been adopted EGR + Exhaust After-Treatment Devices which include – Diesel Oxidation Catalyst Particle Oxidation Catalyst Role- Noise Reduction Direct Exhaust Gas Flow Engine-Out Emission Reduction through After- Treatment parts Exhaust Brake Actuation – Conditions for Exhaust Brake Actuation Engine RPM above 1200 without Acceleration. Exhaust Brake Switch on. Clutch Engaged. ABS not active 44  Mahindra & Mahindra Ltd Truck and Bus Division ICV Clutch System Specifications Diagram – Clutch System 45  Mahindra & Mahindra Ltd Truck and Bus Division Service Standards Pedal Height Adjustment 1. Measure pedal height from floor. Pedal height must be measured at the middle point on the top of rubber pad. 2. If pedal height is more than 167mm from floor, loose the stopper switch and adjust so that pedal is lowered and pedal height is reduced. 3. If pedal height is less than 167mm from floor, loose the stopper switch and adjust so that pedal comes up and pedal height is increased. 4. Ensure clutch pedal travel of 120mm. Adjust lower stopper position at 120mm of pedal travel. 5. Please ensure that pedal height is set as per design as higher or lower pedal height have direct impact on performance. 46  Mahindra & Mahindra Ltd Truck and Bus Division Transmission: MNT 55 ICV Vehicles are equipped with 6 speed gearbox (6 forward gears with 1 over drive and 1 reverse gear) All forward gears are synchromesh type and reverse gear is constant mesh type Double synchro cone mechanism is available in 1st, 2nd, 3rd and 4th gears. A single cone Synchro is used in 5th and 6th gear 1st, 2nd, 3rd & 4th gear Double synchro The Synchro present in 1st, 2nd, 3rd and 4th gear is of double cone Synchro, which consists of Inner Baulking ring, Intermediate Baulking Ring and Outer Baulking ring. Double cone Synchro helps in easier gear shifting. 47  Mahindra & Mahindra Ltd Truck and Bus Division Specification – Gearbox Endplay 48  Mahindra & Mahindra Ltd Truck and Bus Division Exploded Transmission Case Assembly 49  Mahindra & Mahindra Ltd Truck and Bus Division Gear Assembly Cables at gear box end & Lever end 50  Mahindra & Mahindra Ltd Truck and Bus Division Dimensions of Cables at gear box end Select cable can be identified by a RED & shift cable by GREEN. Select cable length - 220±2 mm Shift cable length - 220±2 mm Dimensions of Cables at Lever end Select cable can be identified by a RED & shift cable by GREEN. Select cable length - 200±2 mm Shift cable length - 203±2 mm Shift Pattern Rear Axle 51  Mahindra & Mahindra Ltd Truck and Bus Division Technical Specification Settings required to be done when assembling a crown – pinion assembly. 1. Pinion Bearing Pre-Load - New pinion bearings – 3 to 6 Nm - Used pinion bearings – 2.25 to 5.65 Nm 2. Crown Side Bearing Pre-Load - First tighten flange half adjuster until backlash is zero and now loosen it by two notches. - Turn the plain half adjuster until bearing cup starts to turn, this is zero bearing pre load. - Tighten both adjuster rings by one notch. This is side bearing pre-load. 3. Crown Pinion Backlash Backlash setting for New Gear Set – 0.30 mm Backlash setting for used Gear Set – 0.20 to 0.46 mm To increase the backlash, loosen the Flange half adjuster and tighten the plain half adjuster by same turns and vice versa. 4. Tooth Contact Pattern between Crown Pinion (Refer the Shim calculation formula sheet) 5. Crown Wheel Run out (Value: Max. 0.20 mm) 6. Crown Wheel Face out (Value: Max. 0.20 mm) Note: 1. The Crown & Pinion are a pair & needs to be replaced together as a unit. 2. The Value of Pinion Mounting Depth (PMD) on Crown wheel will be punched on the Pinion face. 3. The PMD value in Meritor is given in “Thou”. 4. For identification of Crown Pinion assembly, matching gear set numbers are given. 52  Mahindra & Mahindra Ltd Truck and Bus Division Wheel Hub Assembly – Exploded View Hub Greasing: 1 Wheel Bearing Grease Brand & Grade Maximile LCG NLGI – 2.5 Front – 840 gms. / Axle 2 Wheel Bearing Grease Quantity Rear – 800 gms. / Axle 3 Hub Greasing Interval Front & Rear – 80,000 Km 4 Front & Rear Hub Play 0.020 – 0.060 mm Rear Hub Play Checking: Hub Play – 0.02 to 0.06 mm Note: The hub play needs to be adjusted by using shims. (1) To increase hub play – Add Shims (2) To decrease hub play – Remove Shims 53  Mahindra & Mahindra Ltd Truck and Bus Division Front Axle Technical Specification: NOTE: Wheel Bearing Grease Quantity - 840 gms. / Axle (420 grms/Hub) 54  Mahindra & Mahindra Ltd Truck and Bus Division Pneumatic Brake System All ICV vehicles from 12T are fitted with WABCO Brake system and operate at a maximum of 10.1 bar pressure (Cut off). The Cut in pressure is 8.8 Bar. The Major components of brake system consists of - Air Compressor – Water Cooled Single Cylinder Air Compressor (All vehicles are equipped with 160 cc WABCO) ADU – Air Drying Unit Air Tanks & Air Pipes Brake Pedal & Dual Brake Valve GHCV - Graduated Hand Control Valve Brake Chambers & Spring Brake Actuators Brake System Specification – 14T Cargo S. No. Parameters 1 System Pressure 10 Bar (Cut In: 8.8 Bar / Cut Off:10.1) 1 Brake Actuation System Make Wabco 2 Brake chambers Type 16 3 Spring Brake Actuators Type 16/24 4 Air Dryer with QSPV Yes 5 Quick Release valve Yes 6 Relay Valve Yes 7 Exhaust Brake Valve Yes 8 ABS system 4S-3M Air Tank - 40ltr 9 Air Tank a)Front – 20 ltr -1 No b)Rear – 20 ltr -1 No 10 ABS System Make - WABCO 11 Brake Foundation Make Brakes India 12 Brake Assy. Front and Rear 360X140 13 Auto Slack Adjuster Automatic Slack Adjuster 55  Mahindra & Mahindra Ltd Truck and Bus Division Component Details – Brakes 56  Mahindra & Mahindra Ltd Truck and Bus Division Brake Circuit 57  Mahindra & Mahindra Ltd Truck and Bus Division Multimeter Continuity Tester – Tool for Diagnosis 1. Voltage checking and resistance checking Voltage Voltage is the electrical force that moves electrons through a conductor. The Unit of Voltage is Volt. It is expressed by the letter “V”. Keep the knob position in the DC volt range. The selected voltage should be higher than the voltage of the power source checked. Voltage value will appear on screen. TESTING OF VOLTAGE POTENTIAL Connect the ground lead of a voltmeter to a body ground or battery ground. Connect the other lead of voltmeter to selected test point. The vehicle ignition may need to be turned ON to check voltage. 58  Mahindra & Mahindra Ltd Truck and Bus Division 2. Resistance 3. Fuses 4. Relays 4 Pin Normally Open Relay Checking: After making the electrical connections for testing the relay, if the bulb glows, then the relay is OK; else the relay is faulty and needs to be replaced. 4 Pin Normally Closed Relay Checking: After making the electrical connections for testing the relay, if the bulb does not glow, the relay is OK. Since it is a normally closed relay, the bulb will glow after removing the relay coil supply i.e. supply at pin no. 85. If the above conditions do not meet, the relay is faulty and needs to be replaced. Relay with De-spike diode: Some relays have in-built diode across pin no 85 & 86 to save the system from surge voltage. When relay is switched off a surge voltage is produced. Sensitive components like ECU may get affected due to high surge voltage 59  Mahindra & Mahindra Ltd Truck and Bus Division Surge voltage which is produced when relay is off will pass through the diode instead of going into the circuit because diode has zero resistance in forward direction When checking a relay with de-spike diode, the connection must be made based on the diode polarity Note: In case of replacement of a relay with de-spike diode, the new relay should also be of de-spike type. Do not use a relay without diode as a replacement. Possible Faults with Wiring Harness Physical damage (Sensor/Actuator Pin Back out, Expanded, Fouling, Burnt etc.) Open Circuit (Open circuit test is also known as continuity test which is measured between 2 ends of a wiring along its length) Ground Circuit (Ground circuit test is checking continuity of wiring with any ground point. It is also known as short to ground) Short Circuit (Short circuit test is checking continuity of one wire with a different wire / with battery positive. It is also known as short to battery) How to Trace Faults (Sample) 60  Mahindra & Mahindra Ltd Truck and Bus Division Sequential steps to follow during wiring checking: 1. Before performing inspection / checking on wiring, always Switch off the Ignition Switch, disconnect the ECU connectors & Sensor / Actuator connector, after which the wiring harness needs to be inspected for complaints. 2. Check whether the Sensor / Actuator connector is properly seated on the sensor / actuator. 3. Check for physical damages, loose connection, fouling, burning, water entry, oxidation/corrosion of pins, routing of harness, wiring insulation damages 4. Check for pin back out, connector pin damages, connector pin expanded, loosely seated wire in connector, broken wire, damaged wire by carrying out physical inspection of the sensor / actuator connector. Refer sample images below for understanding the connector related complaints. Connector pin expanded Connector damaged Connector pin loose / uprooted / backout Carry out the following checks with the connectors and components to confirm whether the trouble symptom occurs. Gently shake the connector up, down and to the left and right Gently shake the wiring harness up, down and to the left and right. Gently shake the fuse / relay board, etc. by hand. Gently shake the wiring harness at the location of hanging and other moving parts 5. Check the male pin on the sensor for burnt, bent or broken pins or physical damages. 6. When inspecting wiring harness for any complaints, always check for Open circuit, Short circuit & Ground circuit. 7. To start with carryout end to end checking - Sensor / Actuator to respective ECU Connector. If complaint is observed, then check form sensor/actuator to respective interconnectors (if applicable) & then from 61  Mahindra & Mahindra Ltd Truck and Bus Division interconnectors to respective ECU Connector. Replace only that harness in which the complaint is observed. 8. At the time of replacement of wiring harness, in order to avoid cross connections between sensors/actuators, in some cases, the wiring color codes can be referred from schematics to understand the connector name. Sample procedure to check Open, Ground and short circuit in wiring harness: 1. Open Circuit test or Continuity test Multimeter "Buzzer" Check Point From To If - Yes If - No Crank Shaft Sensor Pin No. – 1 ECU "A" Connector Pin No. – 105 Open Wiring Wiring Crank Shaft Sensor Pin No. – 2 ECU "A" Connector Pin No. – 84 Circuit Ok Not Ok Crank Shaft Sensor Pin No. – 3 ECU "A" Connector Pin No. – 83 Find whether there is electrical continuity between the pins of the sensor / actuator being checked and the corresponding ECU pin. Set the multimeter (DMM) in continuity mode and ensure a beep sound. ECU Pin out diagram to be referred and continuity between the pin no. 1, 2, 3 of sensor to the corresponding EMS ECU pin no. 105, 84, 83 respectively is to be checked. If continuity is observed, it means the wiring is OK; else if no continuity is observed, it means there is a complaint of open circuit – replace the corresponding wiring harness. 62  Mahindra & Mahindra Ltd Truck and Bus Division 2. Ground Circuit test: Multimeter "Buzzer" Check Point From To Yes No Crank Shaft Sensor Pin No. – 1 Body Ground / Battery –ve Ground Wiring Wiring Crank Shaft Sensor Pin No. – 2 Body Ground / Battery –ve Circuit Not Ok Ok Crank Shaft Sensor Pin No. – 3 Body Ground / Battery –ve Find whether there is electrical continuity between the pins of the sensor / actuator being checked and the ground. Set the multimeter (DMM) in continuity mode and ensure a beep sound. The connector view of sensor / actuator being checked to be referred and continuity between the pin no. 1 and body ground / battery -ve; pin no. 2 and body ground / battery -ve; pin no. 3 and body ground / battery -ve to be checked. If no continuity is observed, it means the wiring is OK; else if continuity is observed, it means there is a complaint of ground circuit – replace the corresponding wiring harness. Sometimes it may be required to shake the wiring under inspection at every 6 – 8 inches apart to verify ground issues. NOTE While checking any part of engine, chassis, for ground it should be free from paint, grease or rust. 63  Mahindra & Mahindra Ltd Truck and Bus Division 3. Short Circuit test: Check Multimeter "Buzzer" From To Point Yes No Crank Shaft Sensor Pin No. – 1 Crank Shaft Sensor Pin No. – 2 Short Wiring Wiring Crank Shaft Sensor Pin No. – 1 Crank Shaft Sensor Pin No. – 3 Circuit Not Ok Ok Crank Shaft Sensor Pin No. – 2 Crank Shaft Sensor Pin No. – 3 Find whether there is electrical continuity between the pins of the sensor / actuator being checked Set the multimeter (DMM) in continuity mode and ensure a beep sound The connector view of sensor / actuator being checked to be referred and continuity between the pin no. 1 and pin no. 2; pin no. 1 and pin no. 3; pin no. 2 and pin no. 3 to be checked. If no continuity is observed, it means the wiring is OK; else if continuity is observed, it means there is a complaint of short circuit – replace the corresponding wiring harness. 64  Mahindra & Mahindra Ltd Truck and Bus Division MDI BSIII CRDe Layout: NEF BSIII CRDe Layout 65  Mahindra & Mahindra Ltd Truck and Bus Division NEF 3.3 BSIV CRDe Layout MDI BSIV CRDe Layout: 66  Mahindra & Mahindra Ltd Truck and Bus Division 25: D25 ECU, andSensors D35 DS& Actuators OBD1 SENSORS ACTUATORS Crank Shaft Position Sensor Cam Phase Sensor Coolant Temperature Sensor Oil Pressure Switch Boost Pressure & Temperature Sensor Rail Pressure Sensor Fuel Injection Pump with Fuel Control TEGR Temperature Sensor Unit Fuel(FCU) / IMV Injectors Intake Throttle Valve Position Sensor EGR Valve – Solenoid EGR Valve Position Sensor Water in Fuel Lamp Turbocharger Position Sensor Tachometer Fuel Temperature Sensor Speedometer Accelerator Pedal Sensor Odometer reading Brake Switch & Clutch Switch Check Lamp DPF Regeneration Switch & DPF Regeneration MIL Inhibit Switch Barometric Sensor ECU NOx Malfunction Lamp HFM Sensor T21: Temperature Sensor (Intercooler) CS018 Ad Blue Warning Lamp Ad Blue Level Indication T0: Temperature Sensor (Chassis) Fuel Gauge, Temperature Gauge Water in Fuel Sensor DPF Regeneration Lamp Neutral Switch Starter Relay Vehicle Speed Sensor Diagnostic Outlet NOx Sensors – Upstream Supply Module Pump NOx Sensors – Downstream Dosing Module (Ad Blue Injector) Fuel Pre-Supply Pump (Feed Pump) T4: Temperature Sensor (DOC Inlet) Relay T5: Temperature Sensor (DOC Outlet) Supply Module Backflow Pump Differential Pressure Sensor (Delta P) Turbocharger Waste Gate Control T6: Temperature Sensor (DPF Outlet) Intake Throttle Valve control Ad Blue – Level, Temperature Sensor Ad Blue Supply Module Pressure Sensor Fuel Float Unit (Fuel Level Sensor) 67 Mahindra & Mahindra Ltd Truck and Bus Division D25 and D35 DS OBD2 68 Mahindra & Mahindra Ltd Truck and Bus Division 69 Mahindra & Mahindra Ltd Truck and Bus Division D25 OBD2 ECU – CS018 70 Mahindra & Mahindra Ltd Truck and Bus Division 71 Mahindra & Mahindra Ltd Truck and Bus Division D35 OBD2 Layout 72  Mahindra & Mahindra Ltd Truck and Bus Division Note: i. In BSVI vehicles, multiple P-Codes may be triggered simultaneously for a single root cause / complaint. These may be termed as Secondary P-Codes, which may be triggered as a resultant of a Primary P-Code. Under such circumstances, attention needs to be given to solve the primary P-Code. The following are the reasons for this: ii. Sharing of common pins: Certain sensors / actuators either share a common supply or a common ground from the ECU. Under this circumstance, if there is complaint with this common pin / corresponding wiring, then the P-Codes pertaining to all those sensors / actuators will be triggered that are associated with the common pins. The details of sensors / actuators sharing the common pins is given in the table below & the same can be referred in the wiring diagrams under EMS ECU Engine Signal & EMS ECU Vehicle Signal sheets: ECU Pin Connection Sensors/Actuators No. Type K72 Multi-Mode Switches & WIF Sensor Ground K13 T5 & T6 Temperature Sensors Ground A14 T21 & Fuel Temperature Sensor Ground A09 BP & T & Oil Pressure Sensors Supply A57 Coolant Temperature & Oil Pressure Sensor Ground A04 EV Fan, Fuel Level Sensor, DPF Regeneration Switch Ground A52 Electronic EGR & ITV Supply K71 Ad Blue Pump & Ad Blue Level, Temperature, Quality Sensor Supply K07 Ad Blue Pump & Ad Blue Level, Temperature, Quality Sensor Ground K68 Brake Switch, Exhaust Brake Switch, Multi-Mode Switches, Water in Fuel Sensor Supply K73 Multi-Mode LED's, Supply Fan Relay, Gear Neutral Switch, Clutch Switch, DPF Regeneration Inhibit Switch, A28 Supply AC Switch iii. Sensor Supply (SSP): Some sensors / actuators share a common supply circuit from within the ECU. These sensors / actuators are grouped, and supply is provided from a common circuit within the ECU. In case of any ground circuit / short circuit occurs in any of these grouped sensors / its corresponding wiring, then the error pertaining to Sensor supply may be triggered along with the corresponding errors of the sensors / actuators that are grouped under this supply circuit. The details of sensors / actuators that are grouped in the ECU for supply are given below: a. Rail Pressure Sensor, Oil Pressure Sensor, Accelerator Pedal Sensor 2, Intake Throttle Valve are grouped together (RPS/OPS/APP2/ITV) b. Accelerator Pedal Sensor 1, Electronic Exhaust Gas Recirculation, Metering Unit (IMV), Electronic Waste Gate Turbocharger (APP1/EGR/Meun/Turbocharger) 73  Mahindra & Mahindra Ltd Truck and Bus Division Eg: If the Oil pressure sensor is grounded, then the error pertaining to Sensor Supply will be triggered along with Rail Pressure Error, as Oil Pressure & Rail Pressure sensors are grouped together Consequential / Secondary Fault Codes: Certain P-codes may be triggered as a consequential effect of failure of a sensor / actuator. Eg: P-Code: (1) P3BA9 – Nox Exceedance – Nox Control Monitoring System, may be associated with failure of many sensors / actuators viz Rail Pressure Sensor, HFM Sensor, Boost Pressure & Temperature Sensor, Coolant Temperature sensor etc, (2) P3BA1 - NOx Exceedance - NOx control monitoring system may be associated with failure of EGR System, Ad Blue Supply Module & Dosing Module etc. In cases where there is possibility of emissions increasing due to failure of a component, the ECU will trigger this consequential error along-side primary error code. In such cases, addressing the root cause of the complaint (i.e addressing the Primary fault codes) will automatically result in clearing of these consequential fault codes. Before checking for any wiring connections for faults, check that all the FUSES are OK. If the fuses are found to be blown, check the source of failure and then rectify. Do not change the fuse without addressing the root-cause. Before replacing any sensor / actuator / ECU, ensure that the wiring harness & supply voltages are free from any complaints, else due to consequential effect, the replaced component might fail. While trouble shooting, to understand the root cause of complaint, avoid replacing the suspected sensor / actuator / wiring directly. Instead it is recommended to refer the diagnostic manual for complaint diagnosis. Once the root cause is identified, after changing the failed components, ensure that the error is cleared using diagnostic software. For certain complaints, especially related to short / ground circuit / sensor failure, there is a possibility that the error might be stored in the ECU permanently even after the affected component is replaced. If this is the case, then the ECU must be replaced & the new ECU flashed with corresponding dataset. Since the failure possibility of sensors/actuator & ECU are minimum, priority needs to be given on inspecting wiring harness first, followed by sensor / actuator & lastly ECU. In certain cases, viz Fuel injectors, IMV are found short circuited to supply / ground, then even after replacing the faulty component if the fault code persists, the replace the ECU & check. It is to be ensured that before installing a new ECU on the vehicle, there are no faults associated with wiring, as it may damage the new ECU also. PRV error is generally a consequential error & it is important to find the root cause which in turn has 74  Mahindra & Mahindra Ltd Truck and Bus Division triggered the PRV error. Healing Cycle: In BSVI vehicles, after successful rectification of faults, a healing cycle needs to be given to the ECU to clear the CEL & / MIL. Follow below mentioned sequence for understanding fault codes, diagnosis, root cause & remedy: Identifying the triggered P-Code in cluster Connect BSVI Diagnostic Tool to understand the component / sensor / actuator associated with the triggered P-Code. Live data can also be made use of to understand the nature of complaint wherever applicable Refer the Diagnostic Manual for understanding the "Possible Causes", necessary "Check Points" to ascertain the root cause & "Remedy" to carryout necessary repairs / replacements as needed to solve the complaint Connect BSVI Diagnostic tool & clear the error codes (In Ignition on condition only) Restart the vehicle / test drive if required to ascertain the fault code is not repeating In the following sections of diagnostic manual, Sensor / actuator image, location, working, wiring schematics & Fault code diagnosis table are given together for easy understanding. One can use “Control F” function to directly search for P-Code & corresponding diagnosis procedure. During the process of interpreting the descriptions of Fault Codes, in majority of the cases, we can conclude the following: a. Fault codes with description “Voltage above upper limit” generally indicates an Open circuit or a Short circuit / Short to battery / Short to supply failure. b. Fault codes with Description “Voltage below lower limit” generally indicates a Ground circuit / Short to ground failure. During the process of diagnosis of a fault code, if the problem persists even after replacing the corresponding wiring harness & Sensor / Actuator, if the fault does not get rectified, then replace ECU & confirm. 75  Mahindra & Mahindra Ltd Truck and Bus Division Note: During oxidation of CO, HC & PM, the temperature at DOC outlet (T5) should be greater than DOC Inlet (T4). This condition is very important for successful completion of regeneration process also. 76  Mahindra & Mahindra Ltd Truck and Bus Division BSVI Platforms: OBD1 – 5.2 OBD2 – 5.3 OBD1 – 5.2 OBD2 – 5.3 DPF Regeneration & Inhibit Switch: 77 Mahindra & Mahindra Ltd Truck and Bus Division 78  Mahindra & Mahindra Ltd Truck and Bus Division Injector Back Leak Test Majority of fuel injector failures are caused by adulterated fuel quality which results into excess wear of internal parts of fuel injectors and ultimately leading to improper spray and injection pattern inside combustion chamber. This also leads to excess suit formation post combustion and carbon deposition on piston rings and fuel injector nozzles and DPF failures. Fuel Injector Back Leak Test- D35 (ICV): Step 1- First unlock two step lock connectors of all fuel injectors. Pull out fuel injector overflow pipe from all the four fuel injectors for using test. Step 2 - Insert connector inside all 4 fuel injectors firmly (press lock) as shown Step 3 - Insert back leak test kit pipes in each fuel injector overflow pipe firmly & put open end pipe in test tubes as shown. 79  Mahindra & Mahindra Ltd Truck and Bus Division Step 4 - Start engine and keep at idle RPM. Collect fuel in Test Tube for duration of one minute - engine in idle RPM. Step 5- Stop the engine & empty the test tubes. Step 6 - Repeat step no.4 for one minute. Step 7 – Measure the fuel collected in all test tubes separately. Measured quantity should be between 5 to 20 ML / minute / Injector at idle RPM If the values are lesser than 5 or greater than 20 ml, then remove the suspected fuel injector & replace with new one Fuel Injector Back Leak Test -D25 & D35DS (CLCV/ILCV/BUS): Step 1- First remove connector locks of all fuel injector overflow pipe. Pull out fuel injector overflow pipe from all the four fuel injectors for using test. Step 3 - Insert back leak test kit pipes in each fuel injector overflow pipe firmly & put open end pipe in test tubes as shown. 80  Mahindra & Mahindra Ltd Truck and Bus Division Step 4 - Start engine and keep at idle RPM. Collect fuel in Test Tube for duration of one minute - engine in idle RPM. Step 5- Stop the engine & empty the test tubes. Step 6 - Repeat step no.4 for one minute. Step 7 – Measure the fuel collected in all test tubes separately. Measured quantity should be between 5 to 20 ML / minute / Injector at idle RPM If the values are lesser than 5 or greater than 20 ml, then remove the suspected fuel injector & replace with new one. 81  Mahindra & Mahindra Ltd Truck and Bus Division CHECKPOINTS FOR DIAGNOSIS OF ENGINE OVERHEAT / COOLANT THROW FROM DGT Major attributers for the said complaint are – I. Leakages in Cooling system (between DGT to Water pump) II. Coolant concentration has been disturbed due to water top-up instead of coolant. III. Sludge / rust formation observed in cooling system, as vehicle is running with Water only for long time which has resulted the same and blockage of Radiator and DGT hose pipelines. IV. Head gasket replacement procedures & check points not followed completely. V. Swapping of DGT Caps VI. Replacement of coolant has not been followed during scheduled service. VII. Coolant hoses has not been replaced as per service recommendations. VIII. Repeat cases occurred due to improper analysis/actions. Eg. Cylinder head flatness and liner projection has not been checked. Improvements on Degassing Tank – D35: Pressure cap color has been modified from black to yellow and a mounting strap has been provided to prevent interchangeability. Breather hose has been added to the pressure cap to eliminate the chances of blockages. UV resistant coating has been added to DGT to address peeling off/fading of DGT outer layer. 82  Mahindra & Mahindra Ltd Truck and Bus Division Modifications in the cooling system - ICV D35 Models: DGT pressure cap operating pressure has been upgraded from 1.0 bar to 1.4 bar to withstand the cooling system pressure. Clamps for radiator bottom hose in & out, radiator bottom metal pipe in & out, water pump inlet & radiator top hose in & out have been upgraded from WORM type to HDCT Type to have a better clamping force & avoid Coolant leakage. Radiator metal pipe length reduced from 488 mm to 359 mm to avoid vibrations & leakages from the weld joint. Radiator outlet hose length increased from 164 mm to 334 mm to accommodate metal pipe length reduction. Dataset ID updated from revision-P2D to P2E for OBD-2 & Rev-E to F for OBD-1 vehicles. The improved dataset includes torque limitation controls with respect to engine coolant temperatures. Previously the torque limitation used to start at 105°C, now it starts at 100°C. This will restrict the system from operating at higher engine temperatures for longer periods. 83  Mahindra & Mahindra Ltd Truck and Bus Division Below are the changes in torque limitation inducement w.r.t coolant temperature after improvements in the dataset: 84  Mahindra & Mahindra Ltd Truck and Bus Division In line to the torque limitation, the high coolant temperature warning tell-tale, CEL & Buzzer will get activated at 103°C (Red Band). Earlier, these indications used to start at 110°. 85