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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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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?
 

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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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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
 

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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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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 doubt very much it was relating to the exhaust elbow work you did. Probably just a coincidence.

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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.
 

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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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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.
I'd still run her nice and hot, underway for a while, before doing exploratory surgery.

The only way I know to check your injectors is to remove them, which isn't usually all that hard. It requires removing the fuel lines first, usually from both the injector and the pump, as they should not be bent, but easily can be, so don't be tempted. There are a variety of ways they are held down to the engine block, but usually straightforward.

Pulling the injector out has one very important consideration. If your engine has sleeves around the injector, they can be holding back coolant, which you can not allow to leak into the cylinder. I've not had a raw water cooled engine, so I'm not sure if any of those have this issue. It's most wise to drain it off first, but you may also need a tool that holds the sleeve in place, while it pulls the injector out. This tool is very handy to have over a lifetime of boating, as it also helps gently extract a stuck injector. Some screw on a little slide hammer, but that's always seemed aggressive.

Once you get them out, you have a pro shop do a pop test, which confirms the spring inside is properly holding back the fuel, until sufficient pressure has accumulated. They also test the spray pattern. Many injectors can have the spring or spray tip replaced, if either are a problem. Some injectors can not and simply need to be replaced.

A quick DIY hack is to just clean up the spray tip yourself and reinstall. When they go back in, all the copper crush washers must be replaced, or they will leak. They are cheap. You also need a torque wrench and spec to know exactly how to tighten them back down. Good idea to clean up the sleeve and especially the seat, before putting them back in.

I'm just trying to answer your how-to question. Again, if she's running fine, I'd take her out and get her good and hot first and then see how she's doing.

Btw, they sell spill containment absorbant booms that you could fashion around your stern, if you're concerned about contaminating the marina. They'd draw attention too, however. They just look like tubes of the white oil absorb pad material, in a string, which float and absorb oil but not water.
 

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Looking at some drawings, I strongly doubt anything you did extracting those bolts would introduce oil into the cylinder or exhaust system.

I agree with @Minnewaska. Run it up to temp and spend an hour at cruising RPM. Check the oil after it's warmed up a bit and again after your run to see if you are truly losing oil.
 

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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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Thanks for the update. Sounds like you can forget the advice about checking the injectors. The common wisdom is look at what you last did and that's the elbow and studs you drilled out. Somehow probably related to that, but don't see offhand what it might be.
 

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noticed it had gone down significantly
How significantly? Was she still putting a sheen on the water, when you got back?

If the engine sat a while and you first checked her cold, then later hot, the filter would have taken up some oil.

Hope you find the culprit.
 

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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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The engine alarm is not good as that means not just low oil level but low oil pressure. Good you stopped the engine when it went off. If there is any good news in this, the leak seems to be significant enough it should be somewhat easier to find.
 

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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.
 

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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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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?
No, no previous changes to the engine, aside from sitting a couple weeks, some idling at the dock and not running up hot. Nothing to out of the normal to have this problem develop and worsen quickly.

First symptom was a slight white smoke/odor while motoring out (~1hr @ typical 2400 rpm cruising at 5 knots).

Sailed a few hours before motoring 5mins into my slip when I noticed the oil sheen in the exhaust.

While doing the routine fresh water flush the oil sheen became worse. Checked the dip stick and lost 1/2 qt oil. Replaced the oil to proper level and motored out again thinking to run WOT and blow out unburned fuel & carbon. Billowing white smoke and increase oil sheen from the exhaust.

Returned back to the dock after an hour and lost 1qt. of oil. I swapped out the mixing elbow for a new one, headed back out and again had the same results of white smoke and rapid loss of oil out the exhaust.

I'm now thinking blown piston rings?
 

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You may want to pull the valve cover first and inspect the area where the pushrods pass through. It is a common fail point when a hole will develop and allow oil to drop directly into the exhaust manifold passage of the head, bypassing the cylinder, which would explain why you don't have significant smoke.. There would also be evidence of the hole by examining the smoke coming from the oil fill hole while running. It is often confused with piston ring wear but piston ring wear doesn't allow for the passage of oil to the exhaust. My suggestion is to examine the yoke between the passages and if nothing is found, remove the head and have it checked at a. machine shop if nothing leaps out at you. Oil dropping onto the dry side of a mixing elbow will produce white smoke at the exhaust temperature rises but will pool oil in the exhaust when it is cooler, like after initial start up and after shut down. It doesn't hurt to look.
 
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