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Discussion Starter · #1 ·
I've got a Yanmar2GM. Oil is coming out of my exhaust, I thought it might have been carbon... but it seems like a lot of oil, and because I am in a busy harbor, I am hesitant to keep running the engine to see if it goes away (oil slick leading back to my boat, not great). Engine is running fine, good water flow... no black smoke, but it is spitting something, leaving an unpleasant, rainbow-like (not certain that is the best way to describe it, but oh well) pattern on the water.

Problem started after I did work on my mixing elbow. Two bolts out of 3 were rusted into the engine body. I had to drill them out. Elbow wasn't damage, not too much build-up either. I was able to re-thread the holes, and to put the elbow back on, but now I've got the oil issue. I did spend a lot of time drilling into the side of the engine, I wonder if I just dislodged something in there, or maybe it's the head gasket? Anyway, I'm at a loss here. I fixed a thing, then messed something else up it seems... engine was running fine before I discovered the elbow bolt problem.

Cheers, help? :/
 

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Discussion Starter · #3 ·
How certain are you that it's oil? Unburned diesel and coolant and leave a slick too. If oil is getting past the rings, it would seem pretty unlikely you wouldn't see some blue smoking. Diesel and coolant usually smoke too (black and white respectively) Perhaps you drilled into an oil passage or coolant passage, but you should quickly see loss of volume, if you did. Worse, you may see the two mixing in the oil pan, which would appear milky on the dipstick, but let's hope not.

I find these catastrophic things, from drilling out the stud, to be unlikely. Unless you so greatly deepened or widened the hole, which would seem you'd have trouble getting a new one back in.

Have you tried running up the rpm, in gear, at the dock to check for smoking?
Well, I am not 100% certain it's oil. I'm just seeing a slick and am making that assumption. My engine doesn't have coolant, so we can rule that out ;).

I don't think I drilled into anything? Although I am not certain what was directly at the back of the studs... hope I didn't mess with anything back there. I did go a bit too deep with one of the holes (top, closest to the front), tho had no trouble putting bolts in after. To be clear, I drilled out the two top bolts (third bottom one was fine).

Ive run the engine at the dock in gear yea, everything seems fine, aside from the "oil". I ran it for 25 min yesterday, it did not stop. Checked into the dipstick hole and oil there seems fine?
 

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Discussion Starter · #5 ·
Diesels run on oil so you have unburnt oil in the water. you are not going to get any oil out of the exhaust manifold so not from drilling out the bolts. since diesels burn oil, oil past the rings will get burnt and be black, blue smoke will be from exhaust valve stem but very hard to see because of the exhaust mixing with the water cooling down the blue oil vapors. excess oil in the water is most likely from worn injectors or injection pump timing
Possible. But because of the timing, I assumed it was related to my messing with the mixing elbow. Although it is very possible that during that repair a problem developed elsewhere (ugh). Will check injectors, see what happens.

Frustrating, considering the engine was running fine prior to this fix (no leaking out from the exhaust). Was doing casual maintenance, when I noticed the two broken bolts on the elbow.
 

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Discussion Starter · #8 ·
Did you run up in gear at the slip, not just for a length of time. If she's running fine, I'd take her out and run her up hot for a while (~1hr), then see how she's doing when you get back.
Ran it in gear in the slip, later in the evening, just because I would likely leave a notable slick behind me if I motored out. May get in trouble with the harbor patrol (am in a busy, very public harbor). Not sure I can pretend not to have noticed ;). I am considering it anyway tho... maybe if I leave real early in the morning, heh.
 

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Discussion Starter · #9 ·
I the absence of any excessive smoke I would guess you are seeing unburnt diesel. That can be caused by something as simple as fouled injectors. When they become fouled they no longer atomize the fuel evenly and instead produce an uneven pattern of heavier drops of fuel which don't burn fully.
I've never had to toy around with injectors. How can I check if they're fouled up? It that easy to test? I have the manual, I'll dive into it later and see what it says.

Yea, bad coincidence maybe. Sucks when that happens.
 

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Discussion Starter · #12 ·
Just an update on this issue (been a while). I left the dock and was able to test the engine. I motored for a few hours, but the oil spill did not stop. I checked oil level on arrival and noticed it had gone down significantly. So my engine is definitely leaking engine oil, it isn't carbon.
Am in port again now, will remove head to see what I discover. I suspect there may be a pin hole...
 

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Discussion Starter · #15 ·
How significantly? Was she still putting a sheen on the water, when you got back?
Like, the oil was near empty. I checked the dipstick on arrival. I ran it for a few hours. I stopped the engine when I heard the oil pressure alarm. I had checked the level before leaving, wasn't full but it was fine.

I was running it hard because I still expected the sheen to be left-over carbon, was not a good idea in this case.
 

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Discussion Starter · #18 ·
Having same exact problem (Yanmar 2GM 13 hp, raw water cooled) related to oil in the exhaust with noticeable sheen. Rapid loss (2 qts /hr), even at idle with and without load. Thankfully Have not ran oil low enough to sound the alarm.

In addition, have large amounts of white (possibly blue) billowing smoke while in gear at cruising RPM. Though, smoking stops if taken out of gear and ran at ~2,800rpm.

My suspicion was oil cooler or turbo failure, but neither installed. No issues with starting or loss of power.
I was going to pull the head off mine to do a check-up but time flies... and I'm on the hard this week. Too much to do...

I had a mechanic come by to see my engine a few days ago, and he suggested I start with removing the head. Did you mess with your engine at all before it developed this problem?
 

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Discussion Starter · #23 ·
Oh that's a good lead. I'll pull the valve cover first then. Splashing back on the 14th, and will be checking the engine that same week. The mechanic I'm speaking to may have a spare head for me.

Cheers, will report back.
 

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Discussion Starter · #24 ·
I pulled the head off today, and my mechanic friend was right. I have a hole in the head, visible through the hole where the exhaust elbow and the head meet. I did not have to remove the head to see this, but it had to be done anyway... could not see a hole while the head was mounted.
139625

My engine was fine before I serviced the elbow, but that was only because layers of carbon were keeping the hole shut. I cleaned them off... and immediately after I started to have oil mixed in with the water. So yea, I've found my problem.
 

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Discussion Starter · #27 ·
Glad you at least figured it out, if not glad to hear how significant it is. What's the next move? New head? Is the engine worth rebuilding? Why do you think this occurred and could there be other failures looming?
It's a bittersweet discovery yes. In all, am glad I've found the issue.

I may have found a replacement head, a mechanic I know was re-building a Yanmar and may be willing to part with the head. Anyway, last time we met up he made the suggestion.

Some of my more hardcore DIY friends suggested getting bronze brazing rods, heating the whole thing up 500 degrees in a bbq and brazing the area (!!!). More reasonably, he mentioned pinning the hole, but I am not sure if that's really a good idea either ;).
 

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Discussion Starter · #31 ·
For now, I've got two options: mechanic friend has a used head, and a 2GM20 that is currently being re-built that I can swap to. I am considering doing a swap, since the alternate has fresh water cooling. Price isn't bad either, would be able to swap parts from my current engine too.
 

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Discussion Starter · #33 ·
I removed the head today and also found a large hole. I imagine far to large to repair- will look for a replacement.
Well well well, that sucks eh? I sympathize. Not glad that you have a hole, but am glad that you too found the culprit.
 
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