25 XP oil pressure too high

[peterhoads]

We overheated our engine due to an unseen water leak, resulting in an oil leak out the rear main seal.  We hauled the engine, replaced the oil seal and went for a sail.  When checking the fluids the next time we went out there was copious amounts of oil on the lower rear of the engine and transmission and a 1/2" deep puddle under the transmission.  Our mechanic thinks the oil pressure is too high, resulting in leakage out the rear main seal.  Question I'm asking "Is this the reason the rear main seal is leaking and if so, why is the pressure too high?"   Is the oil pressure valve fowled, resulting in unlimited oil passage, or is the spring under the ball check weakened due to over heating, or is it something else?

Can anyone enlighten us on this topic?

By the way, check your oil pan for corrosion!  Yes, our raw waterpump shaft was corroded, allowing a small trickle of sea water to dribble down and usner the engine, settling on the front starboard side of the pan, basically rusting it in that area to a cookie-like splotch (in strength).  $350 for a new pan-gotta be from Universal since the Kubota pan dipstick doesn't fit.

Aint' sailing fun?

[Ray & Sandy Erps]

Boy, that's a tough one.  My first guess would be that the rear main is leaking because it got damaged on installation or the oil was leaking from another source back there to begin with.  Rubber seals often cut wear marks into the steal shafts they seal against.  I've always smoothed those out with emory cloth before installing a new seal.  On big highway trucks, they used to actually sell sleeves to go over the damaged area with new seals.

As to the oil pressure question, I guess the only way you're going to know is to put in a mechanical oil pressure guage and see for yourself.  You can pull out the oil sender unit that runs the idiot light and install it there.  There may be a spec for the pressure written some where, but if the pressure is below 60 lbs/in, I would look for another reason for the leak.

Bummer though.  Sounds like some more dirty work ahead.

[Ron Hill]

Peter : We know you have a M25XP, but your production year 1987/88/89/90?
I'll guess that your new rear oil lip seal for the crankshaft is not seated correctly and letting the oil out again!  Your best bet is to pull the engine again, remove the bell housing with xmission, pull off the damper plate, flywheel, remove the starter and check that lip seal.
I seriously doubt that you have too high an oil pressure. 
Pain in the you know what, but it has to happen.
I'm going to write a separate post on that lip seal topic. 

[peterhoads]

Ray and Ron-  Wow, this Forum is great!  What response.  I'll send this info to the mechanic who did the job- maybe he can test the oil pressure and realize his mistake in not checking the crank sealing surface, oil pump and the check valve prior to reassembling.  I'lll update you when it's resolved.

Pete

BTW, Great Escape is a 1988.