Steve,
From the problems you describe, sounds to me like you may have a
couple of problems. The fact that the compression is down on #2 and
#3, even after oiling them, sounds like a head gasket/ head torque
problem. You may be able to readily see this if you or your shop
pulls the head and examines the head, block deck and gasket for
carbon residue. It may not have gotten to the water jacket channels,
or only leaks under compression/ignition pressure. If you
remove/reinstall the head, be sure to re-torque it after a thousand
miles or so
In my experience, MG engines will leak a little bit of oil down the
valve guides with o-ring seals, but not to the extent you have
experienced. I would check the valve guides while the head is off to
be sure they were reamed to the correct size for your valve stems.
Traditional "umbrella seals" should not be necessary.
I suspect that the oil in the cylinders is coming from the rings not
being properly seated. I would think this would happen by about 2500
mile, properly driven--varying engine speed, not over-revving or
lugging. Failure to seat could come from a number of causes--poor
cylinder wall finish, overly slick engine oil during break-in,
cylinders bored out of proper alignment, cheap rings, dumb luck.
The pinging you are experiencing could be the result of contamination
of the charge by oil. It is good that you are taking care of this,
since the pinging will eventually destroy your piston(s). If you
take the pistons out, look for pitting / damage around the crown(s).
Do you know if/how much the head or deck were skimmed in the
rebuild(s)? It soulds like you have a great deal of compression in
#1 and #4--anything over about 9:1 could ping at times with today's
gas.
The leak at the rear could be either the tranny front seal or the
engine rear scroll seal--I'd bet on the engine. I'm told that
excessive clearance around the rear of the crank (loose main bearing
clearance?) will make engine oil leakage worse. Don't know how you
could fix that.
I had a problem with a rebuilt 5 main 1800, in which the rings of #1
did not seat, and pinging was nibbling away at the edges of the
piston crown. Replaced the rings on all four piston at 4,000 mi,
honed cylinder walls, broke it in again, and all was fine.
Good luck! Keep us updated on what you find...
--
Chris Attias
Aptos, CA
'64 MGB
A file that big?
It might be very useful.
But now it is gone.
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