Mercury Marine MCM 3.0L — Layup (Cold Weather / Extended Storage)
Maintenance · Power Package
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
- Be careful working on fuel system; gasoline is extremely flammable
- Be sure engine compartment is well ventilated and no gasoline vapors present
- Stern drive unit should be stored in full down position
Procedure
- Fill fuel tanks with fresh gasoline without alcohol and Quicksilver Gasoline Stabilizer.
- Replace all fuel filters.
- Start engine and check for fuel leaks.
- Run engine to normal operating temperature; shut off and change oil and filter.
- Flush cooling system if operated in salty, polluted or mineral-laden water.
- Remove flame arrestor and, at fast idle (1000-1500 RPM), fog induction system with about 8 ounces of Quicksilver Storage Seal or SAE 20W engine oil; stall engine with last 2 ounces.
- Close fuel shutoff valve if equipped.
- Clean flame arrestor and crankcase ventilation hoses and reinstall.
- Lubricate all items outlined in Lubrication.
- Drain seawater section of cooling system.
- Test closed cooling coolant to withstand lowest expected temperature.
- Service batteries.
- Clean outside of engine and repaint; spray with corrosion and rust preventive.
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.