Engine Oil leak 3GMF

Jun 12, 2013
213
Hunter 40 back creek
I have 83 Hunter with 3gmf engine. I keep getting engine oil under oil pan. We changed the oil pan gasket but under way yesterday at 3/4 throttle for 5 hours noticed oil appeared again? Any ideas?
 
Jan 22, 2008
1,668
Hunter 34 Alameda CA
Possibly I have an idea. Check the interface between the front cover of the engine and the block. The gasket fails and oil runs down at the bottom, then under the oil pan where it drips off and then runs back forward on the fiberglass pan. How do I know? That was this past February's project.

If this is the case, check out the attached pictures and the .pdf file should give you everything you need to change the gasket. I followed this procedure myself and the total cost of repair was $38.00. It took me about 6 hours.

Good luck.
 

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Oct 29, 2005
2,362
Hunter Marine 326 303 Singapore
I've had 3 oil leaks before. First was hand cranking shaft oil seal leaking. Easy fix. Pry out seal and pop in new ones. 2nd was exactly what Allan said. Quite frightening job to do at first. But after done...hey it wasn't that difficult job after all. 3rd was the valve cover gasket (rubber ring) leaks. Easy fix.
 
Nov 6, 2006
10,104
Hunter 34 Mandeville Louisiana
It is a good idea to put eyes on all of the external oil lines and their banjo connections. The service manual in the "Downloads" section of this site will show the location of them.
 
Nov 22, 2011
1,259
Ericson 26-2 San Pedro, CA
It is a good idea to put eyes on all of the external oil lines and their banjo connections. The service manual in the "Downloads" section of this site will show the location of them.
I replaced the external oil lines on my 1GM. The original lines are made of mild steel and are notorious for rusting through. Mine had not yet failed but were showing some signs of rust and I didn't want to take any chances, given the potentially catastrophic consequences of failure. I'm happy to say that the replacement lines are copper, not mild steel. (My replacements are copper, at any rate, and these are Yanmar-branded lines.) I sprayed some extra coats of paint on them for good measure. It was not a difficult job.
 
Oct 29, 2005
2,362
Hunter Marine 326 303 Singapore
Its always good to give the engine a good degreasing and washing after major fix. A clean engine is a happy engine :)