MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - 'Where for out thou oh valve stem oil seals?'

I replaced my sump gasket last weekend and as I was cleaning out the sump before refitting it I noticed some half-circle pieces in the bottom, say 6/8mm diameter.
I've been led to believe these are the valve stem oil seals.
I've noticed a couple of black sotty marks on the back of the garage and also on some of the cars in the works car park (LOL!) so my MG is clearly pumping out some 'dark clouds', but other than that she seems to running okay.
During an MOT I mentioned this to the mechanic who didn't seem to think it was important :o(
Is he right or should I have this fixed as a priority?
Many thanks,
Will
Will Hay

In my experience on the A series 1275 Mini/midget engine which has a similar valve stem design, seals were optional, especially on the exhaust valves. However, apart from the spray painting your exhaust does, (as does mine!) you will find that on overrun or trailling throttle that some oil will leak into the cylinders, and then as you accelerate again, there will be a puff of smoke from the exhaust. If this is affecting the emissions (which it obviously isn't since you got your MOT) then it would need attending to. To get to the seals, you need to support the valve from underneath and although I have used an adaptor with an airline, some suggest coiling rope into the cylinder through the spark plug hole. Then you need to push the spring collar down and the remove the collets to fit the doughnuts to the top of the stem and refit the spring collar and collets. Unless your oil consumption is horrendous, I shouldn't worry about a bit of lubrication on the stems.
Martin

I don't think those o rings did anything anyway. Stop worrying. My B drinks oil 1pt every 300 miles, goes like a bomb though and passes the MOT.
Paul Hollingworth

I see no way how the "O" ring stem seals could've ended up in your oil pan - except in the case that
they may have been previously installed incorrectly.

On MGB's, the stem seals are wedged tightly inside of the valve spring retainers (collars), just under
the valve stem keepers (collets). There is very little room for them to wriggle out of that situation.

On the other hand, I have run into 2-3 MGB engines where I discovered that the "O" rings were
merely slid onto the valve stems, above the valve guides, by an unknowing engine rebuilder.
This is an incorrect installation. In this case, the "O" rings can become brittle, break in half,
and then the bits are carried down into the pan by engine vibration and flowback oil.

All said, I must agree with Paul in that they do not do much in the way of preventing excess oil
from finding it's way down into the guides, anyway.
Daniel Wong

Thanks guys, I appreciate the peace of mind!
Will
Will Hay

This thread was discussed between 06/03/2003 and 07/03/2003

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.