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MG MGB Technical - Oil leak?

I'm looking for any help I can get right now. I recently bought a 1979 MGB and have been having a great time under the hood until yesterday. I was covering the car for the night when I looked at the ground underneath the car. It seems that I am leaking oil from somewhere, but I can't tell where. What seems even stranger to me is that the undercarriage of the car seems to be sprayed with a black oil-like substance (which explains the strange drip-pattern on the ground), however the oil in the engine was changed under 500 miles ago and still looks clean. The oil level appears to be fine, but I want to know if I'm in for a major engine overhaul, or if this could be indicative of a more minor problem.

Thanks in advance,
David
David Palmer

If your oil level in the motor isn't changing, how about the gearbox? When you say the undercarriage looks "sprayed", how far forward or rearward under the car does the oil seem to be covering things. Does it
drip from somewhere just sitting at idle? Until you can figure out where it's coming from there is no good guess as to the severity of the problem.



Kelvin Palmer

David,
A few drips is completely normal for these cars. Oil sealing in the fifties was not up to the standards achieved in todays cars. Your car may be a 1979 model, but it still has 1950s engineering. Don't park them on expensive fancy paving, they will ruin it in no time at all. Hell, if they didn't drip, how would you know if there was any oil in them? It's all a matter of degrees. A drip or two a night is normal. Lot's more than this isn't.
Mike
Mike Howlett

Was your car leaking oil before your recent oil change? If not, check around the base of the oil filter.

Cleaning the engine bay and the entire undercarriage with a spray-on/hose-off engine degreaser will
go a long way in helping you find that leak. After cleaning, pay particular attention to:

1) The hole at the bottom of the transmission bellhousing ( ...and pray that the oil isn't coming from there).

2) The engine timing cover seal.

3) The oil cooler hose connector fittings.

4) The oil filter-engine block adaptor.

5) The oil pressure sender hose.

6) The engine side tappet covers (behind the exhaust manifold).

All are relatively straight-forward to fix - except for #1, which requires that the engine be pulled out of
the car to replace either the rear main seal, or the transmission input shaft seal. If this is so, then it's a
good idea to replace both seals, as well as evaluate the condition of the clutch assembly.
Daniel Wong

Also add possible leaks from the sump-to-engine fitting, quite common!
Bert Holland

MG's don't leak. They mark their territory!

Paul Noble

The black substance could be rustproofing.

The bottom can be sprayed with oil as it drips while motoring.

The rear transmission seal is a major source of leaks, look underneath where the driveshaft enters the transmission housing.

The valve cover gasket can leak if it is overtightened.

Fred Horstmeyer

David, Spreading some newspaper under the car and aligning the edge of the paper with a spot on the car like the door edge will help pinpoint the leak more exactly. To add to what has already been stated here: they do leak and some more than others. A clean with degreaser like Simple Green is a good idea in any case.
Good luck, Pete.
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Peter Thomas

Do any of you have a surefire fix for the tappet covers seals? I've replaced them a couple of times with the neoprene type. Is cork better? It only leaks badly after sustained high rpm driving for extended periods of time. It is a 75' block and seeming in good running order otherwise (67,000 miles). TIA
Luke Staley

I had persistent tappet seal leaks also.
I used Les Bengston's suggestion of attaching the
seals with form-a-gasket to the tappet covers first.
This stops the seals from slipping inside the
engine opening when tightening the tappet cover.

I found I had to retighten the covers after running
for a while, but the form-a-gasket prevented the
aforementioned slippage of the seals.

If they leak again, I'm going to install the one-piece
tappet cover from www.mgbmga.com.
Ronald

The biggest problem on tappet cover and rocker cover seals is that people OVERTIGHTEN them.

Just do them up lightly and they don't leak.

If you are squeezing them enough to make them slip inside then its TOO tight!
Chris at www.octarine-services.fsnet.co.uk

This thread was discussed between 04/09/2001 and 08/09/2001

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