QuestionHoward,
I have been having my 1978 MG Midget 1500 since 1980 and have only recently started experiencing oil blow back through the dip stick. (It had been laid up for about a year with a non-engine related problem but I periodically started the engine).
I installed a new gourmet over the dip stick and this appeared to solve the problem, until I drove it on the highway(60 mph)for about 25 miles. Upon arriving at my destination, I noticed extreme oil leakage and that the oil dipstick was actually pushed out of the tube by about 1/4" (I had checked the oil prior to leaving and made sure that the dipstick was pushed down completely).
Is this a sign that a ring job is necessary?
Would operating the car with the oil fill cap partially open or with a breathable cap harm the engine?
My MG has 78,000 miles and I have never experience this problem before even though the gourmet on the dipstick has been missing for a long time. Also, it may not be relevant, but, I first noticed the problem after my oil was changed and the mechanic overfilled the crankcase.
Thanks for your assistance,
David
AnswerHi David,
You need to do several things.
1. Run a Dry and a Wet compression test or if you know someone with a leak down tester have it tested. (compression gauge is not expensive)
2. If it passes the "Dry & Wet" test, check crankcase venting.
If you are not familiar with the "Dry" & "Wet" compression test let me know and I will go over it for you.
Crankcase pressure is a build up of pressure from leakage past the rings. Some leakage is normal and it is exhausted through the valve cover into the charcoal canister and out into the air. A build up of coked up oil forms in the valve cover, hose and canister over time which can restrict the exhausting of the normal crankcase pressure and then it builds until the pressure starts to push out of gaskets, seals and the dip stick.
If the rings are leaking too much then even a good vent system can't exhaust the amount of blow by.
Howard
