M25XPB, water and oil mixed.

[Jim van Cleve]

The 2000, Westerbeke , m25xp in my 1968 P35
has developed a catastrophic oil-water mingling.
It seemed to happen over a 45 min period, while
fast idling for battery charge. The high temp alarm
sounded at 84'C and after shutdown, found the
water level low, the oil level high, and the
usual sludge.
Head removal shows a good head gasket with no apparent problems.
I'm stumped
Any advice from the experts will
Be greatly appreciated.
Fijijim
1968 P35, Solent Rig
Fiji

[a64pilot]

Well it could be a cracked head or even possibly a cracked cylinder.
But I still bet a head gasket leak that just doesn’t show in the gasket.
If your near a machine shop have the head checked for flatness, and magnafluxed to check for a crack, If it all checks out you may want to get the valves done just cause your there. Do NOT let them talk you into skimming the head just to clean it up. That can cause a lot of pain in a Diesel.

Cylinder wall cracking can be seen almost always by closely inspecting the bores as you turn the crank over with the head off. Cylinder wall cracking is exceedingly rare, but may as well look since the head is off.

Off hand I can’t think of anywhere else coolant can get into the oil? The water pump should have a drain hole that makes that impossible.
Is there an oil cooler?

[Wotname]

I am not familiar with the M25XPB however I offer two suggestions.

1. are you sure the water contamination is from the coolant - it may be coincidental?
2. is the raw water pump belt driven or direct driven? If direct driven off the camshaft or similar, it may be leaking raw water into the crankcase (especially if the weep hole is corroded closed).

[skipperpete]

M25XPB engine

[gonesail]

my westerbeke raw water pump is direct driven. water could get in there if the oil seal goes bad.

[skipperpete]

M25XPB looks like the same engine that Betamarine uses (Kubota) and they have an oil cooler installed as part of the oil filter base, is it possible you have one of these coolers fitted to your Westerbeke? If so , it could be the point where coolant ant lube oil mix.

[Kerry1]

One thing that may not have been mentioned is that sometimes a fault in the casting or in the design may leave too thin a wall between the water jacket and the oil circulatory system which corrodes through and allows water into the sump.

[seabreez]

Originally Posted by Jim van Cleve

The 2000, Westerbeke , m25xp in my 1968 P35
has developed a catastrophic oil-water mingling.
It seemed to happen over a 45 min period, while
fast idling for battery charge. The high temp alarm
sounded at 84'C and after shutdown, found the
water level low, the oil level high, and the
usual sludge.
Head removal shows a good head gasket with no apparent problems.
I'm stumped
Any advice from the experts will
Be greatly appreciated.
Fijijim
1968 P35, Solent Rig
Fiji

If the water pump is direct drive I would suspect that the water pump seal is leaking and water ingression is from that seal. I once diagnosed one on a Volvo engine. How I found this out... I ran the engine until it was warm and I made sure the coolant was full. I drained the oil and then I pressure tested the cooling system like you test an automotive coolant system. Water will leak in the oil side of the system and leak out the oil pan drain hole. Good luck... hard to find.

[Stu Jackson]

I agree, first thing to do is check the rw pump seals. And if it's a Sherwood, replace it with an Oberdorfer.


The only group I know of that has M25XPB is the Catalina 310 group, which you can find here:


https://forums.sailboatowners.com/fo...alina-310.111/


They often have engine discussions and you can search there, too.



The XPB model is significantly different than the XP.