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Mitsubishi 4DQ3 Service Manual

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SERVICE MANUAL
SERVICE MANUAL
MITSUBISHI
DIESEL ENGINE
4DQ3, 4DQ30
MITSUBISHI HEAVY INDUSTRIES, LTD.
No. 5-1, Marunouchi, 2-chome Chiyoda-ku, Tokyo Japan
Phone: Tokyo (03) 212-3111 Telex: J22282, J22443 HISHIJU
99609-50000
DEC 1985

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  • Page 1 SERVICE MANUAL SERVICE MANUAL MITSUBISHI DIESEL ENGINE 4DQ3, 4DQ30 99609-50000 DEC 1985 MITSUBISHI HEAVY INDUSTRIES, LTD. No. 5-1, Marunouchi, 2-chome Chiyoda-ku, Tokyo Japan Phone: Tokyo (03) 212-3111 Telex: J22282, J22443 HISHIJU...
  • Page 2 Mitsubishi 4DQ3 and 4DQ30 Notes: Valve Lash ( cold ) 0.25MM or .010" Head Bolt Torque 87 Ft Lbs Main Bolt Torque 62 Ft Lbs Rod Bolt Torque 40 Ft Lbs Part Number for complete gasket and seal set 3049451031 30494-51031...

  • Page 3: Major Data And Specifications

    MAJOR DATA AND SPECIFICATIONS 4003 Engine model Water-cooled, 4-stroke, swirl-combustion Type chamber type diesel No. of cylinders-arrangement 4-in line Bore x stroke Piston displacement 1490 Compression ratio 21 : 1 Compression pressure kg/cm (psi) 26 (369.7), min (at 150 - 200 rpm) 1 - 3 - 4 - 2 Firing order Direction of rotation...

  • Page 4: Inspection And Repair

    INSPECTION AND REPAIR Cylinder head (I) Inspection Check the gasketed surface of the cylinder head for flatness by using a straightedge and thickness gauge as in the case of checking the crankcase surface s. This check is to be made with the precombustion chamber jets removed.
  • Page 5 Valve guides and valve sea ts (1) Check each valve for carboning, burning, wear or other defect on head; also check cap end and stem for cracks. Replace the valve if damaged. Check each valve guide for wear. Remember, the guide wears down more rapidly at its both ends than at any other parts.
  • Page 6 Valve refacer {a) Set a valve refacer to an angle of 45 degrees. {b) Grind the valve stock to a minimum and, if the margin is less than 1.2 mm (0.04 7 in.), replace the valve. Valve seat cutter Repair an excessively worn valve seat by using a valve seat grinder or valve seat cutter.

  • Page 7: Exhaust Manifold

    'Valve springs Inspect each spring for cracks, and check it for square­ ness, free length and as-installed length against these specifications: Specifications Unit: mm (in.) Repair Item Standard limit 48.85 47.6 Valve spring free length (· 1 .92 32) ( l .874) °...
  • Page 9 Pistons and piston rings Pistons Inspect each piston for any abnormal wear of its sliding surface, for cracks at the crown and for evidence of melting or fusion. Examine the ring grooves for stepped wear and sloped wear. Replace pistons found in bad condition. (2) Measure the outside diameter of piston in two direc­...
  • Page 10 Front of engine (3) Replacing pistons Replace the piston with a new one if the measure­ ment exceeds the service limit. Where any pistons have to be replaced, the variance in weight among the pistons must not exceed the limit. It is recommended that cylinder number be stamped on a piston selected to be used in a particular...
  • Page 11 (6) Replacing piston rinp If the rings are replaced, the gap width will exceed the standard value, but this is not a matter of concern, provided that the service limit is not exceeded. (7) Piston pin bo� Check the piston pin bosses by referring to the topic, Piston pins, piston pin bosses and piston pin bushings, which follows.
  • Page 12 Connecting rod alignment and bearings Check the connecting rod for evidence of cracks, especially cracks in the fillets of its small and big f <o.os ends. Replace the rod if any cra1:k is noted in the fillets. (2) Mount each connecting rod in the connecting rod aligner and check for bend and twist as shown below .
  • Page 13 (4) To dm:k the rod wilh a piston, place lhe rod on the surface plate as shown below, insert a round bar of the crankpin diameter into and through its big end bore, and take measurement at .. A" and "B." The difference between the lwo measurements tells the straighleness of the rod.
  • Page 14 Specifications Unit: mm (in.) Repair Item Standard limit 58 -0 . 035 -0.055 Crankpin diameter (2 283 -0.00138 ) -0.00217 Radial clearance 0.035 - 0.100 0.20 between bearing (0.0079) (0.00138 - 0.00394) and crankpin To measure the inside diameter of the bearing, the bearing fitted to each connecting rod must be secured by tightening the cap bolts to S .5 kg-m (39 .8 lb-ft).
  • Page 16 (2) Crankpins {a) Inspect each crankpin for surface flaws such as roughing, scratches, pitting and bums, and, as necessary, repair the crankpins by grinding to the next undersize or replace the crankshaft. (b) Mike each crankpin to take a total of four readings to detennine the wear, out-of-round and taper.
  • Page 18 (3) End play Check the crankshaft for end play, as shown, by using a thickness gauge at the thrust bearing. If the limit is reached replace the thrust plate. Specifications Unit: mm (in.) '� Repair Item Standard limit >---· Journal width 0.100-0.189 for thrust (0.00394-0.007 44) (0.012)
  • Page 19 (S) Main bearings Inspect each main bearing for evidence of wiping or fatigue failure, for scratches by dirt particles imbedded and for improper seating on the bore (bearing cap). On the basis of findings, determine whether the bearing should be replaced or not. Check each main bearing to be used in engine reassembly to see whether it will provide the speci­...
  • Page 20 Specifications Unit: mm tin.) Standard Item Service limit �gJ Dt: 46.916 D1 - D2 = Intake +0.00394 ) · (1 84708 6.184 -0.01181 W· profile (0.24346) (D1 - Dt - D2 = 6.684 (0.26315) Dt: 45.944 DI - D2 = Exhaust (I 80882 +0.00394 ) ·...
  • Page 21 Specifications Unit: mm (in.) Repair Item Standard limit Fit of camshaft 0.040..., 0.090 0.15 journals in holes (0.00157 -0.00354) (0.0059) (bushings ) Specifications Unit: mm (in.) Service Item Standard limit 5 4 H 7 +0.030 No.l, 2 (2.126 H 7 + g .00118 ) Camshaft Miking camshaft hole ID bushing...
  • Page 22 Timing gears (1) Be sure that the backlash in each mesh is within the repair limit. If the limit is exceeded, reduce the backlash by replacing the worn gear. To measure backlash, use a thickness gauge: put the gauge squarely into between two gear teeth. Specifications Unit: mm (in.) Repair...
  • Page 23 Specifications Unit: mm (in.) Repair Item Standard limit 0.05 - 0.112 Camshaft end play (0.00197 - 0.00441) (0.012) (b) Injection pump drive gear Inspect the gear teeth for damage and also the mounting bolt holes for malcondition. Replace the gear if found in badly damaged condition. (c) Crankshaft gear Replace the gear if its teeth show signs of defective tooth contact, or are excessively worn...

  • Page 24: Piston And Connecting Rod Assembly

    ° ° (b) Heat piston with piston heater up to l 00 C to l 20 ° ° (212 F to 248 F). Install small end of connecting rod into boss and connect piston and piston pin by slowly Combustion inserting piston pin into piston.
  • Page 25 (2) Reassemble the crankcase as follows: (a) Drive three camshaft bushings (1) into camshaft Driving in holes in crankcase by using adapter (A). (If the fit exceeds the repair limit, machine the holes and install bushings.) DRIVING IN CAMSHAFT BUSHING (b) Drive idler shaft (2) into crankcase by using installer (B).
  • Page 26 ( c) Lightly apply engine oil to the crankpins and in­ stall main bearings (upper). Securely engage the bearings with the crankpins. (3) Install the piston assembly as follows: No. 1 ring gap Install connecting rod bearing (upper) (1) into the big end of connecting rod.
  • Page 27 (4) Install the crankshaft as follows: (a) Install thrust plate (I) and two woodruff keys (2) to the crankshaft and drive in crankshaft gear (3) by using installer (A). (b) Install crankshaft to the crankcase. (5) Install the main bearing caps as follows: (a) Apply engine oil to the crankshaft journals and pms, and install the crankshaft in the crankcase secure­...
  • Page 28 (b) Tighten connecting rod clamping nuts to a torque of 5.5 kgm (39.771 lb.ft). (7) Install the retainers and gaskets as follows: (a) Install retainers (1) to the external peripheries of main bearing caps No. 1 and No. 3 with the flange facing the case inside.
  • Page 29 (d) Install sleeve onto the rear end of crankshaft. Apply clean engine oil to the internal surface of oil seal {I) and secure it with bolts (2) by using oil seal aligner, ( e) Apply Atom jet at the tip of bolts (3) as they fit into four through-bolt holes in the bearing cap.
  • Page 30 ( d) Tighten camshaft thrust plate to crankcase by using machining holes in camshaft gear. (9 ) Install the idler gear as follows: (a) Install idler gear by matching the timing mark on each gear. Timing gear match marks meeting each other 1-Camshaft gear 3-ldler gear 2-Cran kshaft gear...
  • Page 31 (10) Install the oil pump assembly as follows: (a) Install oil pump into the oil pump installation hole in the crankcase and mesh the pump drive gear with camshaft pump drive gear. (b) Tighten bolt and secure the oil pump. (11 ) Install the oil pan.
  • Page 32 Install stem seal (3) to the valve guide. Completely fit the breast of the seal in the guide groove. (b) Install valve (4), valve spring (5) and retainer(6) in this order. Compress the spring with a valve lifter to install valve cotter (7) securely. Install caps (8) when installing rocker shaft assembly.
  • Page 33 (15) Install the push rods and rocker shafts as follows: (a) Insert the push rods (1) into the tappets. (b) Install rocker shaft assembly as follows: (c) Insert "O" rings (3) into oil pipe (2) and connect the oil pipe to the front and rear rocker shafts.

  • Page 35: Lubricating System

    LUBRICATING SYSTEM 1.Piston 2-0il filter 3-Crankshaft 4-0il strainer 5-Rocker arm 6-Rocker shaft 7-0il pressure alarm switch 8-0il pump 9-Fuel injection pump 10-Water pump Lubrication oil circuit 1. Lube oil circulation A trochoid rotary pump draws oil in the oil pan and delivers it under pressure to a full-flow oil filter, from which the cleaned oil is forwarded into the oil gallery inside the crankcase.
  • Page 36 2- 2 Inspectio n ( 1) Running clearance between outer rotor and inner rotor Using a thickness gauge, check the clearance at various positions. If the reading exceeds the service limit; replace both rotors. Specifications Unit: mm (in.) Service Item Standard limit Clearance between...

  • Page 37: Oil Filter

    2-3 Reassembly (1) Install inner rotor to pump shaft with pin. (2) Place pump shaft in pump case. Install pump drive gear to the shaft with pin. (3) Place outer rotor in pump case, and install pump case cover complete with gasket and oil strainer. (NOTES] a) If pump shaft or drive gear has been replaced, a new pin hole must be made by drilling...

  • Page 39: Water Pump

    2-2 Inspection Clean the thennostat, place it in a hot-water tub, and � test it for thennostatic action by heating the tub to raise the water temperature. The valve should start ° ° opening at 76.5 ± 2 C ( 169.7 ± 3.6 F) and be fully °...
  • Page 40 Remove snap ring (6) from the water pump shaft. Pull shaft (8) off the pulley side on pump case ( 4) and remove bearings (7) and (9) from the shaft. 3-2 Inspection (1) Examine the pump operation by slowly rotating it. the pump is erratic in rotation, replace the bearings with new ones.
  • Page 41 Reassembly (1) Install bearings (2) on pump shaft (1) and install the shaft in pump case (3). (2) Install snap ring (4) in case on pulley side. (3) Install unit seal (5) in impeller (6) and secure the impeller to the shaft. (4) Install cover (7).

  • Page 42: Visual Inspection

    BENCH TEST When the engine is overhauled, it is advisable to conduct (f) The relationship between the load and running­ the bench tests for checking the engine performance. in period is as follows: The purpose of bench tests is to make sure that each After running-in the engine, check the valve major component has been properly serviced.

  • Page 43: Maintenance Standards

    MAINTENANCE STANDARDS Unit· mm (in ) Nominal Assembly standard Repair limit Service limit Group Item Remedy Remarks dimension [Standard clearance] [Clearance] [Clearance] Maximum rpm Varies according to customers' specifications. Asjust governor. (no-load) Minimum rpm (no-load) 650 -700 26 kg/cm (370 psi), min 20 kg/cm Oil and water temperatures: Compression pressure...
  • Page 47 m:mm m. (" ) 77.90 Standard -·-· - 0.25 (0.0098) 77.15 oversize Measure in the direction ± 0.015 -0.2 transverse to piston pin..� 0.50 (0.0197) 77.40 oversize 0. 75 (0.0295) 77.65 oversize -----------· Protrusion above 0.35 -0.75 � (Q) ���...
  • Page 49 Unit; mm (in.) "Cl I o .50 I 0.15 -0.35 End play Replace connecting rods. (0.0197) (0.0059 -0.0138) "' .§ Difference in weight l:l. (±0.88 oz) ±25g among rods per engine ·;: � Flatness Grind or replace. "' � "' 0.15 (0.0059), max (0.020) >-.
  • Page 50 Unit· mm (in) Nominal Assembly standard Repair limit Service limit Remedy Remarks Item dimension [Standard clearance) [ Clearance) [ Clearance] Group 0.05 - 0.15 Thrust journal width [ 0.35 ] 26 (1.024 Replace thrust plate. I (Q0020 -o .0059) in boss (0.0138) Fit of shaft in holes 0.09T-0.045T...
  • Page 51 SEALANT APPLICATION DATA Where to apply Mating face or parts Sealant Remarks Apply to bottom face for oil Crankcase Three Bond 1102 pan. Apply to both sides of cork Oil pan gasket Atmojet packing. Front/rear attaching faces Apply to periphery of rubber ThreeBond l 207C packing.

  • Page 52: Tightening Torque

    TIGHTENING TORQUE Important bolts and nuts Unit: kg,m (lb-ft) Torque Item Cylinder head bolts 12.0 ± 0.5 (86.8 ± 3.6) Main bearing cap bolts 8.5 ± 0.5 (61.5 ± 3.6) Connecting rod cap bolts 5.5±0.5 (39.8 ± 3.6) Rocker shaft bracket bolts 1.5 ±...
  • Page 53 General bolts and nuts (2) The values listed below have a tolerance of ±10%. When an impact wrench is used, a torque up to ( 1) The values listed in this chart are for standard and including 14 ·kg-m ( 101 lb-ft) has a tolerance bolts.

  • Page 54: Special Service Tools

    SPECIAL SERVICE TOOLS Unit: mm Tool No. Tool name Drawing or sketch Used for: Installing valve guides Valve guide 30691-10200 installer Material: S53C 1-Valve guide 3-Cylinder head installer A-Guide length 2-Valve guide outside hole • Removing valve guides o.sc Valve guide 31391-10500 remover 1-Valve guide...
  • Page 55 Unit: mm Tool No. Tool name Drawing or sketch Used for: Connecting pressure gauge to engine for compression measurement 30691-11100 Adaptor Removing idler shaft Idler shaft MH061077 puller Rotating crank pulley for engine cranking Crank ing 30691-21800 handle Installing camshaft thrust plate 34491.00300 Socket...
  • Page 56 Unit: mm Used for: Tool No. Drawing or sketch Tool name Universal 30091-01101 extension Removing/installing piston rings 31391-12 900 Piston ring to ol Idler bush- Removing/installing idler bushing 30 691-5 1900 ing puller...
  • Page 57 Unit: mm Tool No. Tool name Drawing sketch Used for: camshaft Removing/installing bushings Adaptor (MH061080) Camshaft 3-Camshaft bushing 1-Rod bushing 30691-00010 2-Adaptor installer set Adaptor (MH061081) To be used together with guide piece (30891-04 700) as a set � (31391-12300) Installing crankshaft rear oil Sleeve 30691-13010...

  • Page 58: Troubleshooting

    TROUBLESHOOTING Engine lacks Abnormal ex­ Engine Engine will not start haust smoke hunts power Engine turns Engine does ] When over but does not turn operating not start Complaint Possible cause Insufficient fuel supply to injection pump Greater variance of injec­ tion quantity Defective injection pump seals...
  • Page 59 ( • For detailed information refer to the separate chart.) Defective lubri­ Abnormal Defective cation system water tem­ alternator � �� ������--1 perature rise >--���� � ---, Remedy ·� " >< • • Check and replace if necessary. • • •...
  • Page 60 Abnormal ex­ Engine haust smoke hunts Complaint Possible cause Engine is too cold. Radiator dissipates heat excessively > "' Insufficient coolant Failure of radiator to dis­ sipate heat properly Water leak through cylinder head gasket Cracks in crankcase water jacket Defective starter switch Defective starter magnetic switch...
  • Page 61 ( • For detailed information refer to the separate chart.) D e fective lubri­ Defective cation system alternator · E <l) <l) <l) <l) 'O ..c:: Remed y 0. ;!: E "" <l) " <l) ..� .8 1: " "...

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