Mercury Marine MCM 3.0L — Main Bearing Replacement
Repair & overhaul · Main Bearings
For the Mercury Marine MCM 3.0L, from the Mercury Marine service manual.
Applies to: General Motors MCM 3.0L / 3.0LX engine
Before you start
- DO NOT rotate the crankshaft while gauging plastic is between bearing and journal
Procedure
- Remove and inspect crankshaft.
- Remove main bearings from cylinder block and main bearing caps.
- Coat bearing surfaces of new, correct-size main bearing with oil and install in block and caps; check clearance.
- Install crankshaft.
- Torque all main bearing caps EXCEPT the rear main cap to 75 lb. ft. (102 N-m).
- Torque rear main bearing cap to 10-12 lb. ft. (14-16 N-m); tap end of crankshaft rearward then forward with a lead hammer.
- Torque rear main bearing cap to 75 lb. ft. (102 N-m).
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Main bearing cap bolts: 75 lb. ft. (102 N-m)
- Rear main cap initial: 10-12 Amazon eBay FridayParts $169.30 lb. ft. (14-16 Amazon eBay FridayParts $135.00 N-m)
Source: Mercury Marine service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.