New member and new owner of a Yanmar 4JH3-DTE in a 24 ft cruiser. Engine seams fine if a bit neglected by previous owner. 2005 model with 900 hours up. A little blue smoke on cold start but it clears up when warm. Not using any oil worth mentioning. There are few things I need to do on the engine and have a couple of questions.

I need to conserve the engine for winter soon. Done this before on other engines but Iím not sure if the thermostat is on the sea water side or the engine coolant side on this engine. Do I need to run the engine until warm and thermostat open before flushing with anti-freeze on sea water side of cooling system.?

Need to do a valve clearance check and adjustment. I found a procedure on google search but just wondered is anyone could confirm the following is correct?

On the Yanmar 4JH the number 1 cylinder is the one closest to the flywheel (transmission). The valve arrangement from the flywheel end is, exhaust-intake, exhaust-intake, exhaust-intake, exhaust-intake. The valve adjustment for both intake and exhaust valves is .008in (.2mm). Double check the recommended clearance for your engine.

1. Using a 17mm wrench, loosen all four injection line one turn at the injector. This will prevent the engine from starting while you are turning it by hand. Remove the valve cover.

2. Turn the engine clockwise from the alternator end of the engine. This is #4 cylinder end. Turn the engine until the exhaust valve opens (goes down) and begins to close (move up) on #4 cylinder. Continue barring until the intake valve on #4 cyl. just begins to move (open). STOP. This puts number one cylinder at TDC compression.

3. Adjust #1 cyl. (flywheel end) exhaust and intake valves, #2 cyl. intake and #3 cyl. exhaust.

4. Bar the engine 360 degrees. Now adjust the valves that were missed in step #3. The exhaust on #2 cyl, the intake on #3 cyl and the intake and exhaust on #4 cyl. I usually chalk or mark the valves that are first adjusted in step #3. Then adjust the ones that are not marked during this adjustment cycle.

5. Tighten the high pressure fuel lines , put the valve cover back on and start the engine.

Thanks all. I'm glad I found this forum :-)

Bill
Norway