Oil Leak on 6.2L

C

C-SIDE

Member
Sep 6, 2009
313
Michigan City, IN
Boat Info
2001 340 Sundancer
Engines
6.2L w/ genny
So I noticed some oil on the bilge right below my starboard engine on the right side. I felt around where the oil is leaking and it appears to be under the exhaust manifold. While I'm no mechanic, I'm scratching my head on this. Any ideas on where the leak is coming from or why the exhaust manifold. The oil is black with no water mixed in

Thanks all
Chris


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Last edited:
"So I noticed some oil on the bilge right below my starboard engine on the right side. I felt around where the oil is leaking and it appears to be under the exhaust manifold. While I'm no mechanic, I'm scratching my head on this. Any ideas on where the leak is coming from or why the exhaust manifold. The oil is black with no water mixed in"

It's not making sense because you forgot about gravity :smt001

Back on track... oil can leak from somewhere up top, then travel down and eventually drip from somewhere else. See if you can follow the trail - a mirror on a stick, phone camera, flashlight, etc. If your engine is kept clean, this should be pretty easy. If the engine and bilge is dirty, the job gets a little more difficult. My first guess would be a loose valve cover.

You said "right side" of engine. Is this a v-drive or stern drive, and do you mean stbd side of engine? Or, how about... inboard or outboard side of stbd engine?
 
Engine and Bilge are clean. It's the starboard engine on the right had side of the engine. I have V-drives. The oil leak is around the oil dipstick, which is right below the exhaust manifold - this is where is traced it too.

Had a compression check about a month and engine is fine. It also purrs like a kitten


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"right" side of things is a confusing term - it can be construed in different ways. But, since you now said "dipstick and v-drive", that makes more sense.

So we have the port side of the stbd engine? Clean bilge - good - makes things much easier to find leak sources.

OK - in the first post you mentioned (or at least that was the way I read it) it was dripping off the underside of the manifold. But it sounds like you have now found the drip is from the dipstick fitting? Seems like you found the source? If it's not wet above it, you've found it. Take a better look at that area and see if something is amiss with the fitting. Or, follow the dipstick tube up and find the spot where it is no longer dry. Now go straight/vertically above it and you should find another wet spot - follow that - etc, etc. Is the dipstick cap on fully?

Another way... use an engine oil dye kit.
 
Follow ths link
http://www.mercruiserparts.com/v-8-inboard-engines
to your specific engine (need ser.#) to view a diagram of the oil pan and pump.
It may help you think where your leak is from...you may have a banjo bolt on the very bottom of the pan that's loose....?
 
Is your oil filter mounted above manifold? If so check oil filter to see if it is leaking. You may have to get down and look right under the oil filter for sign of oil.
 
So I did more hunting and discovered that the oil is leaking, I think, right around where the transmission is attached to the engine. I can't tell if its a head gasket or around the intake manifold. There is so much crap (hoses/lines and other stuff) its hard to tell. Either way, its beyond my skill set to fix.

I have next weekend, then my boating season is over to next spring. I'll get this looked at and fixed when she gets put away.

Thanks for your time and input
 
Valve cover gasket?
 
@ronDDS - I don't think its the valve cover as the bottom of the cover was clean. That would be an easy fix, so hoping I'm wrong.
 
when you run the engine do you smell oil burning? If not, it's not the valve cover -the manifold will sometimes start to "cook" the oil. By the transmission you likely have a crankcase oil cooler and and a transmission fluid cooler. Could be coming out of one of those. Is it black/amber or red?
 
Good point ronDDS. There is no smell of burning oil. The fluid is black as oil and come to think of it, it wasn't very hot when I cleaned it up, which was shortly after I was running for about an hour

Both temp and oil pressure readings are fine too
 
Check the oil lines that lead into the coolers. Could be your source.

You'd need to lose an awful lot of oil to see changes in oil pressure.
 
What was the outcome?
I have a small spot also, from the starboard engine on the starboard side! (Btw, both my engines have two dip sticks, each!) black in color.
 
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