Yanmar Oil Leak

[jimlarsen]

We are looking at a boat to purchase. Everything looks great on the boat except for oil leaking out of the fill cap on top the motor. My hunch is that this could be a sign of serious trouble, but the salesman wants me to think it is nothing to be concerned about. What do you think? I have included a picture. The boat is 13 years old with 1200 hours on the engine.

 

[quadrille38]

I'm not an engine expert but might it be as simple as a gasket on the fill cap?

 

[chuckwayne]

It shouldn't be doing that..... there also appears to be a leak around the front of the valve cover - that's not uncommon, but both could be a sign of excess crankcase pressure. This can be caused by a blocked crankcase vent, not a big deal, or serious issues like worn valve stems and/or seals that could require a head rebuild. I would get a good yanmar mechanic to check it out

 

[kloudie1]

The fill cap has an o-ring seal .. open the cap and look for the ring.. if it is there, then plugged vent (the little 4 bolt cover on the bottom of the picture) or some serious worn piston rings.
If the o-ring is missing, I'd want to get one installed and then make sure that stops the leak.

 

[Charles Erwin]

Since the salesman concludes it is not a real problem - you are entitled to ask him to please explain exactly what is causing this oil leak and so why it is "not a problem".

Once he explains the "very simple" reasons underpinning this leak - I am sure he and the owner will agree to fix the problem (at no cost) - because the fix is so very trivial.

Particularly - is this excessive crankcase pressure? If so, then what is the causing this pressure? Or is this simply failed cover gasket? If that is so, then why didn't the owner fix this simple problem to start with? Who told these folks what the trivial problem is and are they willing to let you talk to the guy who diagnosed the problem?

Post these explanations you get here if you feel further comment from people like Kloudie and the rest of us might be useful to you

Charles

 

[RichH]

Once he explains the "very simple" reasons underpinning this leak - I am sure he and the owner will agree to fix the problem (at no cost) - because the fix is so very trivial.

VERY well stated.

Probably a blocked crankcase breather tube - minor fix.

 

[kloudie1]

Might have too much oil in it too.. foaming (from the crank hitting the oil while running) would inhibit drainage from the cover and could do that.. If oil is the correct level, and the o-ring in the cap is there and is not cracked, there is something screwy going on!

 

[jimlarsen]

Thanks to all of you for the quick replies. This is exactly the type of help I was hoping for. I'm glad to hear it could be an easy fix. And thanks for confirming my suspicions that it could be something much more expensive!

 

[kloudie1]

Ya welcome, JimLarsen.. and Welcome aboard ..

 

[HMT2]

Had a similar issue on my Yanmar 2gm. I thought it was coming from the oil fill cap, but it actually came from a tiny amount of oil leaking from a spot in the picture below and ran back to the cap. It's so insignificant I just haven't gotten around to putting JBWeld on it. FWIW my Yanmar dealer is stumped by it. It's an 83 H 31