14249A 2 Mercruiser COVER, CRANKCASE FRONT

1. Major Specifications
Only the items marked with are different from the 4D31 engine. Group 11 Engine
Group 12 Lubrication
Group 14 Cooling
Group 16 Engine Electrical
2. Service Standards
Only the items marked with are different from the 4D31 engine.2.1 Service Standards Table
Group 11 Engine
Group 12 Lubrication
Group 13 Fuel And Engine Control
Group 14 Cooling
Group 16 Engine Electrical
2.2 Tightening Torque Table
Group 11 Engine
Group 12 Lubrication
Group 13 Fuel And Engine Control
Group 14 Cooling
Group 15 Intake And Exhaust
Group 16 Engine Electrical
3. Special Tools
Group 11 Engine
Group 12 Lubrication
Group 13 Fuel And Engine Control
Group 14 Cooling
Group 16 Engine Electrical
1. Service Procedures
1.1 Crankcase and Main Moving Parts
Disassembly
(1) Piston Projection Incorrect piston projection adversely affects the engine performance. If measurement are out of specification, check parts for clearance.(a) Hold the dial indicator on the crankcase top surface to make zero adjustment.(b) Locate the piston TDC with the dial indicator.(c) Measure projections at three points on the piston top surface to obtain the average value.(2) Connecting Rod End Play Measure the end play of each connecting rod. If the limit is exceeded, replace the connecting rod.(3) Removal of Piston Withdraw the piston from the crankcase, pushing it up together with the connecting rod. 1. If the piston pin is hard to remove, heat piston with a piston heater or hot water.2. Do not remove the connecting rod bolts from the connecting rod unless defective. If the bolt is damaged, install a new connecting rod bolt by referring to 1.1.3 (5) (c).(4) Removal of Piston Ring To remove the piston rings, use Piston Ring Tool (special tool).(5) Crankshaft End Play If the end play exceeds the limit, replace the thrust plate with an oversize.Three oversize thrust plates are available: +0.15, +0.30, and +0.45 The thrust plates on both ends of the bearing cap need not be of the same size; however, use the one of the same size for those at the rear end of the crankcase and in rear of the bearing cap.(6) Removal of Main Bearing Cap (at front and rear end only) To remove the main bearing cap, use Bearing Cap Extractor (special tool).(7) Removal of Crankshaft Gear To remove the crankshaft gear, use Gear Puller (special tool). It is not necessary to remove the crankshaft gear unless defect is evident.Inspection
(1) Measurement of Crankcase I.D. Measure the crankcase I.D. at the six points shown in illustration.If the I.D. exceeds the limit, replace or bore to oversize.If the crankcase is to be used without being bored, grind the ring ridge at its top with a ridge reamer.(2) Selection of Oversize (a) An oversize must be determined in consideration of the part developing the most serious wear from all cylinder I.D. measurements. Available oversizes (2 types): +0.5, +1.00 mm(b) Using a micrometer, measure the O.D. of individual oversize pistons to be used.(c) Bore and hone the cylinder to obtain the nominal value for the cylinder to piston clearance. 1. Even if only one cylinder requires boring, make sure that all cylinders are bored to the same oversize.2. Replace the piston and the piston rings with the corresponding oversizes.(3) Crankcase Top Surface Distortion If distortion of crankcase top surface exceeds the limit, correct with a surface grinder. Crankcase must be ground only to the extent that the piston projection does not exceed the nominal value.