Mercury Marine MCM 3.0L — Cylinder Head Installation
Repair & overhaul
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
- The head gasket may be holding cylinder head to block; use care when prying, DO NOT damage gasket surfaces
- Ensure cooling water supply is available before starting the engine
Procedure
- Place head gasket in position over dowel pins.
- Carefully set cylinder head in place over dowel pins.
- Coat threads of head bolts with Quicksilver Perfect Seal and install finger-tight.
- Torque head bolts in sequence to 90 lb. ft. (122 N-m) to insure gasket sealing.
- Install push rods, rocker arm assemblies and lifter restrictors in their original positions.
- Torque rocker arm nuts to 20 lb. ft. (27 N-m).
- Install intake manifold, rocker arm covers, exhaust manifolds, spark plugs and removed components.
- Provide adequate water supply before starting engine.
- Start engine, set timing, set idle speed and check for leaks.
Specs & values
- Cylinder head bolts: 90 lb. ft. (122 N-m)
- Rocker arm nuts: 20 lb. ft. (27 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.