Yanmar 2GM20F Oil leak

[John North]

After running my engine at high revs 35000 + for more than an hour, I put my boat to bed. The next time I checked my oil, I saw a lot of oil in the pan under the engine. I had lost about 1/2 liter. I topped off the oil and restarted the engine and discovered that oil was running quite freely out of the gasket on the right hand side of the timing gear cover. Where is the oil coming from? Is there supposed to be oil behind the cover? Is the crankshaft seal shot? If so, how difficult is the job to replace the gasket or seal? I don't want to start taking the pulleys and belts off without some sense that I can do the job. I have worked on engines before, but not a diesel.Any advice? Do you have a diagram of the parts?

 

[Steve Dion]

Get the service manual.

John:Get the service manual for the engine. They have a lot of good stuff in there. Don't have mine at home now so I cannot check it for you, but it is a good investment at about $40-50.PS: at 35,000 + rpms you should have been flying !!!!!!!!!!! <grin>

 

[Gordon Torresen]

Oil leak

I think it is safe to assume that you meant 3500 RPM for one hour. That being the case, the engine should be mad at you. Recommended RPM for long cruising is 80% of max, about 2900. Short intervals of higher RPM will not cause harm. The leak to which you refer is not related to the high revolutions. If the location can be pinpointed, we might be able to give advise. If it is from a gasket, quite often tightening something will solve the problem. When you say "the right side", I assume you mean the side towards the right side of the boat. Here you are dealing with the governor and other things that may require Yanmar expertise.  We would be happy to help if you can be more specific. The service manual is also a great help.

 

[John North]

Reply to Gordon

Yes I did exagerate a little by a factor of 10. I meant to say 3500 rpm.The leak is coming from the right hand side of the gasket between the gear cover and the crankcase as you look at it from the pulley side of the engine.It streams from the joint quite liberally. I should get a shop manual. I bought a Clymer's, but I'm not sure that it will be good enough.I also might need the work to be done by Yanmar service. What would you recommend?John North

 

[Gordon Torresen]

Oil leak

I believe we now have the area of the leak isolated. Where you describe is the area near the oil filter. Could you be seeing an oil filter leak? The gear case in that area is rather deep, making it very rigid, ie: less prone to deflect if one fastener is loose. There are several bolts in the area that could require tightening, one of which holds the pivot of the alternator. You might try tightening them but be careful of overtightening. They are long and stretchy bolts and it is sometimes dirricult to sense the proper torque. If the gasket is damaged, get a GOOD yanmar mechanic to make the replacement. Removing that cover entails doing things with the injector pump and the governor, not simple. There are pressurized oil passages between the block and that gear case. It is possible that your sustained running at high RPM could have exacerbated a marginally tightened gasket surface.  I would be interested in knowing a more precise location of the failed gasket and in hearing of how you make the repair.