Oil in exhaust water

Peter

.
Apr 26, 2016
271
Macgregor 26M ca
OK forum members, I need some help with this one:
On a Volvo MD6A (1975 vintage) when the motor is started a trace of engine oil is visible in the exhaust water.

What could be the possible causes of this?

The motor is in an Albin Ballad, a close cousin to the Vega.

Peter
#1331 'Sin Tacha'
 
Sep 24, 2008
346
Worn rings - when the rings are worn oil is burned or exhausted when the
exhaust valve is open. I'm not a mechanic but that would be my guess.
 
Feb 13, 2010
528
Peter, Been setting her thinking about your problem. Speculating! The
only ways I can think of that lubricating oil (not a diesel sheen on the
water) can get into the cooling water is a valve stem leaking and the
oil being blown into the exhaust ahead of the exhaust gasses is one
possible cause. Another is that the "o" rings in the water pump might be
worn and oil getting into the water there is possible but unlikely. I
had a pump on an engine leak water into the oil because the previous
owner had plugged the drain hole in the bottom of the pump because he
didn't like the water and oil draining into the bilge. New O rings and
taking the screw out of the drain hole solved that problem. If the hole
is open it's pretty hard for oil to get in the water. I think it is
possible to install the "o" ring on the wrong side of the bearing in the
pump and that could cover the drain hole. When the engine is shut off
the water tries to drain down into the water intake and might draw a
little vacum in the pump and it is possible it could suck oil slowly
into the pump??? It seems to me that the oil you are seeing might be
diesel in the exhaust. That might be incomplete combustion or gasket
leaks. I doubt that it is coming from worn rings as the engine burns
that oil. Of course the sign of that is the lowering of crankcase oil.
In a really bad case you can't shut the engine off because it sucks
crankcase oil up around the rings and the engine keeps running after you
have shut the fuel off. My best guess is the exhaust valves are leaking
oil down the stem and its running into the exaust as the engine sets
idle. Doug
 
Oct 30, 2019
1,459
Doug,
Thanks for your thoughts on the engine problem. This is on a boat I've never seen; I'm just going by what the broker told me. I suspect you may be right in that it might be fuel, rather than lubrication oil. Also, it seems that others have had a similar problem in the water pump area.

The boat is a 1975 Albin Ballad, and is for sale not too far away from me. I've always liked the Ballad (never sailed one though) and really like the quality of Albin Marine's work, so I may take a peek at this one ... just out of curiosity of course ;-)

Whatever the cause, it certainly raises a 'red flag' in the engine compartment!

Peter
#1331 'Sin Tacha'