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MG MGA - Where does my oil go?

The oil level on my dipstick goes from max to min after about 250 miles, sometimes quicker.
There are no obvious oil leaks, other than a small drop at the back of the engine, where it joins the gearbox.
It does nor appear to be burning, as there is no noticable smoke, and the oil pressure is always between 60 & 75.
The head gasket is new, and the head was skimmed at that time.
Any ideas please?
Nigel Munford

Nigel

What engine are you running? - MGA or B?

Steve

Steve Gyles

Hi Nigel. There are really very few possibilites. Either you are leaking oil, burning oil, or a combination of the two. I am wondering what weight of engine oil you are using? 5W30, or 10W30 are too light, and can both burn and leak out somehat faster than thicker oils. I personally recommend 20W50 oil for your engine.(in warm weather anyway) You say there is a small leak at the rear of your engine. Unfortunately, even a very slow drip can cause an amazingly rapid and considerable oil loss! Try putting clean cardboard under the engine, start the engine and watch the oil leak out at idle. Then have someone rev the engine to about 3500 RPM, and hold it there for several minutes. My guess is that at high revs you are probably losing lots of oil, due to your "small" leak. If so, then probably your crankshaft scroll is worn, or you have defective/loose gaskets. You might want to also check that your sump bolts, side cover bolts, and valve cover bolts are properly tightened and are not leaking. You could also check the oil pressure relief valve, and oil filter / oil cooler joints for leaks also. Hope this helps, GLenn
Glenn

Steve,
MGA 1600 engine (1960)
Glenn,
Thanks for the tips. I do use 20/50
Nigel Munford

If you are missing oil is in one of two places, on the ground or in the air. Your description sounds like burning oil as there isn't a major leak.
First verify that it isn't being blown out the downdraft tube attached to the front tappet cover. Do you have a stock type valve cover that runs an air tube to the front air cleaner?
Does the engine show a significant amounts of blow-by?
Once you determine that the oil is burning and not leaking or blowing out the vent there are two places oil gets burned. #1 poor oil control at the rings or #2 poor oil control at the valve guides or Both.
Poor oil control at the rings is usually accompanied by blow-by and is caused by worn rings and bores.
Sometimes an oil control ring can seize to a piston fill with carbon and not do it's job. In this case the compression could be good and there be no blow-by but oil could come past the rings.
Valve seals and guide wear can be checked easily. Put the piston at the top and check the valves to that piston. Remove the spring and check for condition and location of the "O" ring seal. Wiggle the valve in the guide to check for wear. Worn guide/valve stem sloppieness indicates the need for a head removal.
Good luck
Randy
R J Brown

I had a mysterious oil consumption problem that took almost three years, and many competent advisors attempts, to diagnose. I had good power and compression but changed the rings twice (some said the chrome rings had not seated), redid the valve guides, etc. The oil loss continued.

The third time the head was off, I had new hardened valve seats installed, and new valves fitted.

The machine shop decided to check the valve seating so applied a vacuum to the head. It sealed OK from the piston side, but would not seal from the inlet side. They discouvered a very small hole in one inlet port through to the push rod cavity. This hole got bigger as the head got hot, and allowed oil to be sucked up from the sump in to the inlet.

Solution was that they pick out the hole until it was a little bigger, and then filled it with a 2-part epoxy with steel (like Devcon). I've had no problems since, and have been using this head since (about 5 years now)including a 4500 mile round trip to MG2001 in Minneapolis.

The car will be at Whistler, BC, for NAMGAR's GT 32. You need to determine if the oil from your engine is leaking out or burning off, as per the suggestions above. Peter.
P. Tilbury

My car has solved the oil loss problem for me. The hood latch is stuck, so now I don't have to check the oil!
Mark

This thread was discussed between 29/10/2006 and 31/10/2006

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