Sludge found in Bilge & under oil pan

[MAINE ATOMIC4]

Hi Everyone,

About half way through the season, I noticed oil sludge in the bilge of my Pearson 28. I determined it was coming from the engine, but couldn't find the leak. I checked the oil level repeatedly through the season and it seemed to hold fairly constant, although I'll concede that quantifying it with the dip is not a perfect science.

Anyway, during winter commissioning I reached under the oil pan and felt a sludge. It was partly oil...partly seawater goo from the packing (I think).

I pumped out the oil using a drill pump and a newly installed Moyer oil change kit (thanks MM!). The total contents of oil removed was (1) 2-liter bottle.

So, is my oil pan corroded through? Could it be coming from the shaft seal? Maybe I overfilled the oil last season? Is this an A4 life ender? How can I check for leak source given the way the mounting and flywheel block all reasonable views of the pan?

I basically need a knowledgable person to recommend a next step for me so I can continue to efficiently troubleshoot over the winter.

Thanks!

[sastanley]

A possible leak source is the water pump seal. It has two...one keeps the seawater on the impeller side of the shaft, and the interior seal keeps the oil in the crankcase. In between the two seals is a weep hole, that may drip water or oil, depending on which seal may be bad.

The bottom of my pan is a little 'sludgie' too. Can you get an inspection mirror under there and see anything??

[MAINE ATOMIC4]

I tried a mirror, but it shows what I expect to see....a corroded pan and a bunch of nasty sludge.

Based on the fact that the oil level did not drop substaintially over the half-season, I expect that "seeing" a leak may be difficult.

I did rebuild the water pump 2 seasons ago and used new oil/water side lip seals. Would an oil leak through the lip seal only occur during operation?

thanks for the idea.

-John

[ILikeRust]

My first thought also was the water pump.

Do you know for sure the sludge gunk wasn't there before? Maybe it's been there a long time, slowly and gradually building up, and you just hadn't noticed it until recently?

I bought my boat a little more than a year ago and when I pulled the engine out, I discovered all kinds of lovely, goopy gunk under it. It clearly had been there a long time.

[Loki9]

The oil pan is a thick casting and it seems unlikely that it is corroded all the way through. Much more common are leaky seals and gaskets, so I would try to eliminate them first.

[JOHN COOKSON]

You may have a slight leak at the front seal of the engine. The oil picks up dust and so on as it slowly runs over the pan. That is what mine does. I clean it up a couple times a year otherwise ignore it. I figure the oil protects the pan from rusting. There is not enough oil for me to worry about - yet that is.
I would clean it up and monitor the situation for a while.

TRUE GRIT

[smosher]

I had the same problem and I found out when I replaced the water pump after a rebuild I didn't tighen the bolts enough so that a small drip would occur.

Steve

[ndutton]

Do you store spare oil on board? If yes, might want to check them. Those paper thin plastic bottles don't tolerate much vibration and chafe.

[sastanley]

Neil, The P.O. on my boat would leave the pump & drain pan (along with a gallon of oil in its container) in the settee locker after he changed the oil. I don't know if he even emptied the pan..I bet he just let it ooze out of the pump & the pan into the bilge and pumped it overboard with the gallons of rain water that seeped in as well..

[edwardc]

Originally Posted by JOHN COOKSON

You may have a slight leak at the front seal of the engine. ...

I believe there isn't any front seal on the A4. The inclined mounting keeps the oil level below that point. If you overfill it, or tip it forward too far, the oil will just run out.

[JOHN COOKSON]

Originally Posted by edwardc

I believe there isn't any front seal on the A4. The inclined mounting keeps the oil level below that point. If you overfill it, or tip it forward too far, the oil will just run out.

I should have said the oil slinger or whatever is up there that keeps the oil in the engine. I remember something about drain holes that get plugged? I haven't delved into it but somehow a bit of oil does come out the front of the engine.
I'll be in touch so I know what I'm doing before I take on the fix.

TRUE GRIT

[ILikeRust]

Originally Posted by JOHN COOKSON

I should have said the oil slinger or whatever is up there that keeps the oil in the engine. I remember something about drain holes that get plugged? I haven't delved into it but somehow a bit of oil does come out the front of the engine.

As Edward observes, there is nothing that keeps the oil in the front of the engine. There is no seal. Just a little gap between the front and of the crankshaft and the crankcase/oil pan.

If you tip the engine forward, oil will dribble out. Even if your engine is brand-spanking new, or newly-rebuilt, with nothing clogged, leaking or malfunctioning. I guarantee it. DAMHIKT.

If the engine is kept level, or - as is the case on most of our boats - slightly tilted downwards in the rear, and the oil is not overfilled, the oil can't spill out.

I'm trying to visually remember that part of the crankcase - there might be, as you suggest, a small flange or something that is designed to deflect any sprayed oil back into the crankcase. I'm just not sure how that could "malfunction" and allow oil to run out the front.

[ILikeRust]

Aha!

A quick forum search finds this, from Don:

Most oil leaks occur along the carburetor side of the engine. Starting at the flywheel end of the engine and working rearward, leaks could be from the oil sending unit directly behind the flywheel housing (or from its connecting fittings), from under the valve cover, from between the block and fuel pump, or from around the oil pressure regulating valve.

If the leak seems to be from the rear of the engine, the rear seal around the output coupling could be leaking. However, almost all leaks from along the carburetor side of the engine usually run back along the upper ledge of the oil pan and end up dripping off the aft end of the engine. Therefore, to be certain that the rear oil seal is really leaking, it is necessary to thoroughly clean the rear end of the oil pan so that the oil can actually be seen to run down from the seal.

On the starter side of the engine, leaks are usually limited to the area of the water pump and accessory drive, with the shaft seal of the pump (the seal toward the engine) being the most likely. If this seal is leaking, you should be able to feel oil dripping out of the weep hole in the housing of the pump, between the mounting flange and the impeller section. Leaks from the oil seal of the water pump have the potential to leak up to a quart per hour in worst cases.

Still in the area of the water pump, the lower bolt of the mounting flange of the pump, or the lower bolt in the flange of the accessory drive (both of which enter into the crankcase), will at times allow a small amount of oil to drip from out of the crankcase.

If the leak is clearly coming from the front of the engine, it could be that the return holes in the flywheel housing below the air seal (or "slinger seal") around the front of the crankshaft are clogged. When these holes are clogged, oil being flung outward by the tapered collar around the front of the crankshaft cannot drain back into the crankcase, and it is leaking (instead) down behind the flywheel, along the front face of the flywheel housing, and out through a drain hole in the bottom of the same housing.

From this thread.

[MAINE ATOMIC4]

Bill T,

Thanks for finding that thorough explanation from Don...that post is exactly what I needed to feel confident starting the hunt for the mystery leak location.

I'll report back when it's found and how I fixed it (or why I decided to leave it be!). Thanks everyone!

[campbdon]

Would there be a likely common cause for water getting into the oil AND watery oily sludge reappearing in the bilge (even after removal)? The latter happens even when sitting at dock not running the engine and with the cooling water drain plug and 4 water pump screws loosedned off. I will do troubleshooting checking compression and trying to localize where the oil leaking is coming from but in meantime thought I'd put this question to the forum.
I do definitely keep the raw water intake closed when the engine is not running.

Thanks.
DonC

[zellerj]

You would be better off starting a new thread. The thread you added to is 12 years old.

[Al Schober]

I'd put my money on the aft oil seal in the reversing gear.