Stu,
What type of air cleaner is on the car? If you are using the early oil
bath without the restrictor in the breather pipe the oil may be getting
sucked in through it and into the intake. My engine was rebuilt by the PO. I
when trough it and found it is bored .030 over. It has 80 psi of oil
pressure when cold and drops to about 20psi when hot. It uses about the same
amount of oil yours does now. It dosen't smoke and the plugs are always dry.
This is my first TD so I don't know if this consumption is normal. You may
want to run a wet compresion test to see if the rings are the problem and
maybe also a leak-down test and see if this gives you an answer.
Alan Gruskos
From: Stuart Keen <simbafish@home.com>
To: MG <mg-t@autox.team.net>
Sent: Monday, May 08, 2000 7:28 AM
Subject: Oil Usage
> Knowing little about a XPAG automotive engine for a 51 MGTD MkII, I am
> asking what can be done to lessen the oil usage. First a little history.
>
> The engine was rebuilt in 1978 by previous owner. When I got the car a
> year ago, it ran good, but number four plug was always getting fouled up
> with oil. Other three plugs were dry. Oil pressure was between 60 and 80
> psi, depending on speed. My oil consumption was low. Then the crankshaft
broke!
>
> During rebuilt, the machine shop discovered the cylinders had previously
> been bored to plus .038, yet .040 rings and pistons had been inserted.
> Very tight, lots of friction, LOTS OF HEAT. However, boring the
> cylinders now for plus .040 cleaned up the scoring. The manual for a
> MKII says compression should be between 110 and 150. Before the crank
> broke, the compression was 175! I was suspicious about the high reading,
> but didn't know why at the time.
>
> Now the engine has been rebuilt with new rings and pistons, tappets and
> crank, plus seals and gaskets. The original valves and guides and cam
> were retained since there was only 9000 miles on the 1978 rebuilt engine
> when the crank broke. This time the valves were ground and the seats
> checked okay.
>
> I have now put on about 3000 miles on the newly rebuilt engine. My oil
> consumption is about 600 miles to the qt. Before the crank broke, it was
> about a qt every 2000 miles. All four plugs are now fouling up with
> oil, before it was just one plug. However, my compression is right up to
> snuff, all reading between 145 and 150, the maximum according to the
> manual. My oil pressure is still, as before, between 60 and 80 psi.
>
> How is the oil getting into the combustion chamber? Would lowering the
> oil pressure help and how would that be accomplished? Is there any
> additive I might put into the engine that would gradually seal up
> wherever the oil is seeping in? Engine runs great but I'd like to
> eliminate the higher than normal oil consumption which is fouling the
> plugs (though I am told by a previous dealer of MGs that the Abingdon's
> policy said, if consumption was less than a qt per 500 miles, don't
worry.)
>
> Stu Keen
> Venice, Fl
> simbafish@home.com
> 51 MGTD MKII
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