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MG MGB Technical - Oil consumption with good compression

All,

I'm having an oil consumption problem on my '79B that my shop is telling me is not breather/leak related. (Just want to get that out there so folks don't throw that out there.)

My shop is telling me that my car has good compression on all cylinders (about 185), but that my engine needs a ring job! I've always been told that good compression but with heavy oil consumption would mean the valves need work... am I wrong about this?

Confused,
Terry
Terry

Terry,

I'm having a similar issue with my '80B, except I'm not sure that mine isn't a leak issue... I don't have a lot of blue-ish smoke or anything (although slightly black along with some sooty plugs.)

When was your engine last rebuilt (if at all?) If it's recently, maybe one of your rings hasn't seated?

Regards,
Kevin
Kevin

Sometimes the oil control rings are bad even if the compression (top) ring is OK. Sometimes the oil control rings get gummed up from lack of oil changes, and there are some remedies to free them up that might be worth trying. I have not personally used any, so I cannot vouch for such.
If nothing helps, then pulling the head off and checking the piston bore for excessive wear will tell the tale.
Andrew Blackley

Kevin,

The engine was rebuilt about 4 years ago... I've driven it about 20,000 miles since then. I didn't rebuild it, though, my shop did.

Andrew,

That may be it. I'll ask my shop to be more specific on what exactly they think the problem is. I guess I need to see something to understand it!

Still Confused,
Terry
Terry

Terry,

One thing I forgot to mention... your compression seems very high on the engine; the compression on these cars when they left the factory was 155-160psi!

Kevin
Kevin

Compression's not excessively high. Terry, could be oil control ring problem as Andrew says or bad valve guide(s).
Paul K

Mine started burning oil immediately after fitting a Burgess cylinder head. Apparently the extra pressure imposed by the reworked head causes already worn rings to blow. That's what PB told me anyway. I don't have blue smoke either, but I get through a pint of oil every 300 miles.
Mike
Mike Howlett

I can get my 1963 MGB to run higher than 4,000 RPM.
where do I start looking, If its the carbs, how do I made it run richer, I have 2 SUs.
Timming seems ok, it starts easy.

Thanks to all of you who have answer all my other questions.
David A.

This thread was discussed between 16/08/2002 and 18/08/2002

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