D348 INDUSTRIAL & MARINE ENGINES Caterpillar

TYPICAL EXAMPLE

start by:

a) remove oil pump

b) remove front timing gear housing

c) remove flywheel housing

d) remove pistons

1. Fasten a hoist to the crankshaft.

2. Remove the nuts and washers that hold the main bearing caps in place.

NOTE: Main bearing cap No. 7 has the thrust bearing on each side of the cap.

TYPICAL EXAMPLE

3. Remove the main bearing caps. Remove the crankshaft from the cylinder block. The weight is 535 lb. (241 kg).

NOTE: Make reference to SPECIAL INSTRUCTION Form No. SEHS6713 for procedures for crankshaft reconditioning.

TYPICAL EXAMPLE

4. Remove the main bearings from the main bearing caps and the cylinder block.

NOTE: Make reference to GUIDELINE FOR REUSABLE PARTS: MAIN AND CONNECTING ROD BEARINGS, FORM NO. SEBF8009.

Install Crankshaft

1. Turn the front and rear idler gears until "V" mark on the gears are toward crankshaft when installed.

2. Clean the surfaces in the cylinder block for the main bearings. Install the upper halves of the main bearings in the block.

NOTE: Install the main bearing dry when the clearance checks are made. Put clean engine oil on the main bearings for final assembly.

3. Fasten a hoist to the crankshaft and put it in position in the cylinder block with "V" marks (1) on front and rear crankshaft gears in alignment with "V" marks on front and rear idler gears.

4. Clean the main bearing caps. Install the lower halves of the main bearings in the main bearing caps.

NOTE: Be sure the tabs on the back side of the main bearings fit in the grooves of the main bearing caps and cylinder block.

5. Check the main bearing clearance with Plastigage (A). Install the Plastigage between the crankshaft and the main bearing.

NOTE: When the bearing clearance is checked and the engine is in a vertical position, such as in the vehicle, the crankshaft will have to be lifted up with a force equal to the weight of the crankshaft and held against the upper halves of the main bearings to get a correct measurement with Plastigage (A). The Plastigage will not hold the weight of the crankshaft and give a correct indication. If the engine is in a horizontal position, such as on an engine stand, it is not necessary to hold the crankshaft up. Do not turn crankshaft when Plastigage is in position to check clearance.

6. Put clean SAE 30 oil on the threads and face of the main bearing nuts. Install the main bearing caps, washers and nuts. Tighten the nuts to a torque of 60 ± 5 lb.ft. (80 ± 7 N·m) in letter sequence A, B, C, D. Put a mark on the nuts and studs, then turn each nut 120 ± 5° more in sequence. Remove the main bearing caps and measure the width of Plastigage (A) which will be the bearing clearance. The main bearing clearance with a new bearing must be .0058 to .0096 in. (0.147 to 0.244 mm). Maximum permissible clearance with used main bearings is .010 in. (0.25 mm).

7. Put clean SAE 30 oil on threads and face of the main bearing nuts. Put the main bearing caps in the same position on the block as it was when it was removed. Install the washers and nuts and tighten the nuts to a torque of 60 ± 5 lb.ft. (80 ± 7 N·m) in sequence A, B, C, D. Put a mark on the nuts and studs, then turn each nut 120 ± 5° more in sequence.

8. The No. 7 main bearing cap has a thrust bearing on each side of the main bearing cap. The end play of the crankshaft is controlled by the thrust bearing. Check the end play of the crankshaft with tooling (B). The end play must be .010 to .022 in. (0.25 to 0.56 mm). Make a replacement of the thrust bearing if needed. Install the thrust bearing in the groove in the main bering cap with the aluminum side toward the crankshaft.

end by:

a) install pistons

b) install flywheel housing

c) install front timing gear housing

d) install oil pump

e) check fuel injection pump timing (see FUEL INJECTION PUMP TIMING in TESTING AND ADJUSTING)