Tiny, intermittent oil leak

[Breakin Away]

I've had a couple times in the last month when I found a very small amount of oil (a few drops at most) under my motor. One time it was on the port side, another it was on the starboard side. In between those two occurrences, there were a couple times I motored and there was no oil leak apparent, including a 6 hour day of motoring with no oil drops observed. But the very next day I motored for another 6 hours (with some heeling during a couple 30 kt gusts) and found a couple drops of oil.

The two times I found oil I had motorsailed and had some heeling in the direction consistent with which side I found the oil. My guess is that there is a slow weeping through a seal somewhere which accumulates somewhere on the fins and other horizontal elements, and when the boat heels it falls off on the low side of the engine. It's also possible that the weeping of oil only occurs when the motor runs while the boat is heeling.

A couple of other notes: I have occasionally found tiny amount of oil on the engine housing this season. While I don't remember exact location, I do believe it was relatively high up on the motor. Also, I did have some water leakage from my Sherwood raw water pump in May which led me to have it rebuilt and to replace the raw water hose back to the HX. I did replace the flange gasket with the water pump. I've inspected the edge of the oil pan flange and noticed a tiny amount of corrosion around the very edge, but no signs that it's any more than superficial, and only about an inch long in one spot. (I'll recheck this next time I go to the boat.) Also, frequent checks of the dipstick verify that there is no measurable loss of oil. It's always at the top line on the stick.

I'd be interested in your suggestions on how to diagnose and locate the source of this small leak. Are there flange bolts I should tighten somewhere? I think it's overkill to remove/replace the oil pan at this point. Would prefer to eliminate other problems first.

The boat is now hauled out. I'll be changing the oil and winterizing in the next couple of days, so may not get much diagnosis done. I'll try to take a few pictures if I see anything interesting. I expect that running the motor for 20 minutes without any load (to heat up the oil) isn't going to put enough stress on it to see any leakage. Also there won't be any heeling with the boat on the stands (there better not be!!!).

[Noah]

Curious; how do you cool your engine when running 20 min. on the hard?

[KWKloeber]

Breakin

If you can't recall where the oil was, kinda tough to point to where to "tighten, 'eh?  Seems like an issue to file away until next season, clean the surfaces well and when/IF it happens post pics. One general spot to check is the valve cover/gasket.

Note that your oil sump has no gasket, it is silicone'd on.

[KWKloeber]

Curious; how do you cool your engine when running 20 min. on the hard?

N-

EZ-PZ.

Drop the pump supply hose in a reservoir (bucket) and add a water supply (garden hose).  You can use the bilge in a pinch.

-k

[Stu Jackson]

Curious; how do you cool your engine when running 20 min. on the hard?

Here's how:

Winterizing an Engine on the Hard (Thanks to Maine Sail) - NEVER connect a hose to your raw water pump inlet - NEVER!!!

http://forums.catalina.sailboatowners.com/showthread.php?p=873073&highlight=winterizing


Doing this for the intended oil leak forensics seems wasteful and potentially harmful.  I'd wait til spring, ain't goin' anywhere for the next few months.

[Stu Jackson]

You're right.  Sorry, sbo changed their software and some of those links may be broken.

I'll see if I can find it again.

[Stu Jackson]

Ken, I just tried.  I found the post itself, but the video was no longer there.  And it's not on MS's new 'site, either.

[Breakin Away]

Breakin

If you can't recall where the oil was, kinda tough to point to where to "tighten, 'eh?  Seems like an issue to file away until next season, clean the surfaces well and when/IF it happens post pics. One general spot to check is the valve cover/gasket.

Note that your oil sump has no gasket, it is silicone'd on.

Yeah, I meant to post several days ago, when I'd have a few days to try some stuff. But with nighttime temps next weekend going to freezing, and my being out of town the week after that, I decided I had to get started with winterizing sooner than expected. So today I warmed up the oil, changed it, and pumped the antifreeze through. (Still need to winterize the rest of the boat.) I don't think any oil is leaking from the oil pan. Today I noticed that a little oil accumulated on the rectangular casing just above the oil pan flange, and other accumulation points have all been well above the oil pan flange. Last time I checked gravity pulled down, not up, so I think it's coming from up high. After reading several Tech Wiki links, one possibility is the gasket for my Sherwood pump. When I rebuilt and reinstalled it last spring (sorry Ob fans!), I did not use any Permatex or other sealant on the gasket. Maybe after a season things are seeping through. I'll look at that more closely. I'll also look at the valve cover as well.

Today while warming up the motor I also discovered a coolant leak through the circulator pump's weep hole behind/under the pulley (as well as some corrosion around there), so my coolant pump might be failing. It is possible that such an issue could also lead to an oil leak from behind the circulator pump's gasket? I saw something about oil leaks due to loose bolts on the coolant pump, so I'll give that a look too.

I'm amazed at how perfectly things run all season on the water, but as soon as I get on the hard I find all sorts of problems. It may be a busy winter.

[Stu Jackson]

Stu

What's the link to the orig post?

Wouldn't that be the very one I posted that doesn't work?    It's from the 101 Topics.

[Stu Jackson]

Ken, try this:  https://forums.sailboatowners.com/index.php?threads/winterizing-a-diesel-engine-on-the-hard.136339/&highlight=winterizing

[KWKloeber]

the video was no longer there.  And it's not on MS's new 'site, either.

Stu

Here yah go. .. link to stick in the 101s:

https://youtu.be/PKky09u1fGU

[Stu Jackson]

Thanks, Ken.  Posted on the 101 Topic list.

[Ron Hill]

Breaking : Your best bet (as suggested) is to wipe down the engine over the winter and get it as clean as possible.  Then in the spring you'll just have to inspect the engine after running it and hopefully you'll find where the oil leak is migrating from.
The best places to look at are where oil is most likely to come from : around the valve cover -especially the aft end, around the oil filter attachment, around the oil breather hose and around the oil pressure switch plug.

A few thoughts

[Breakin Away]

Quick follow-up on this small intermittent oil "leak":

I recently inspected the end of the breather hose and found a small amount of used motor oil (1/2 tsp or so) in a low point just inside the end. This, alone, is more than the few drops I had seen migrating onto the motor fins and ultimately into the pan under the motor. From the location and orientation of this breather hose, I am almost certain that the breather hose is the source of the oil "leak", and that oil is not seeping through any seals. As pointed out before, the oil drops were only noted when motor sailing under gusty conditions that caused the boat to heel. Other times I could motor for many hours with no oil noted. I suspect that the gusty heeling conditions allow a little oil to splash into the breather hose and work its way to the end.

I have wiped the oil out of the breather hose, and after de-winterization and launch I will keep an eye on it to verify what motoring conditions might cause oil to seep into the hose.

[KWKloeber]

Why is the crankcase breather discharging to the pan. On the B series (XPB anyway) Wb routed it to the air breather (dumb 45 cut on the hose and tied into place against the silencer).

Route it right to the intake manifold?