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MG MGA - Gas in the oil?

I've been noticing that the oil in the car doesn't seem to have the longevity I'd expect. It seems to go black almost immediately.

I've always assumed this was an issue of an old car with deposits of old oil in the car.

However this weekend I realized that the car has been running consistently rich for a period of time.

Is the oil going black a sign of gas in the oil from washing the cylinder walls?

Thanks
T McCarthy

Do you have the standard MGA engine ventilation system fitted? A non standard system (I had one fitted not so long ago) could result in all the horrible vapours etc contaminating the oil.

Steve
Steve Gyles

Yes standard.

So is the blackening indeed an indicator of gas contamination?
T McCarthy

If you have gas in the oil you can smell it on the dipstick. It may turn the oil black quicker if there is quite a bit of gas as it is washing the inside of your engine.
John H

Check that your choke jets are returning fully. If they remain slightly open, neat fuel washes past into the cylinder diluting the oil. I noticed that after 20-30 miles running the oil pressure droppped; though I was puzzled by this I could find no diagnosis. The result after a track day at Goodwood was the crankchaft bearings gave up. Close examination of the carbs after the necessary strip down showed the problem.
Robert Divine

T - take a look at your spark plugs - if black you are running rich and that would, in excess, lead to fuel blowby down to the crankcase and dilute the oil.
Steven B

My A's oil did the same. Runs lean and cool. I pulled the oil pan and found 1/2" build up of black sludge that was too thick to drain. After cleaning it out, seems better.
Scott

This thread was discussed between 02/07/2007 and 07/07/2007

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