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MGB 77 MGB Oil Leak

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kyreb1862

kyreb1862

Jedi Knight
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I've noticed that my 77 B usually has a fine coating of oil on its valve cover. This tends to accumulate until it runs down the block and just generally makes a mess. I first thought it was a leaky valve cover gasket that allowed the oil to get on the block and then I realized that it seems to be coming from the oil cap. There seems to be a fine oil mist coming from around the oil filler cap. Any ideas what is causing this or what I can do to correct it ?

Regards John
 
John - cover the opening with duct tape & see if that stops the leak....if it does, new cap!

Oh, MG's don't leak - they mark their territory.
 
If you removed part of your pollution system you may just need to vent the whole system or convert it to a specific year system with a PCV valve. OR your rings and cylinders are so bad that the crankcase is getting pressurized. If you are still running all the correct pollution stuff then who knows!
 
bob67bgt said:
If you removed part of your pollution system you may just need to vent the whole system or convert it to a specific year system with a PCV valve. OR your rings and cylinders are so bad that the crankcase is getting pressurized. If you are still running all the correct pollution stuff then who knows!
Click to expand...
Exactly! OEM setup on a 77 has an airpump, a egr valve, and enough hose and fittings to plumb a house. The idea of some of these parts is to collect any vapors from the upper crankcase and burn them. Causes of increased crankcase pressure that may not be cured, only covered, by new cap include rings as bob mentioned - or an overfull crankcase due to improper dipstick, or frothing of oil due to bad pump. As old as it is it might by your state standards be exempt from annual emissions testing so in theory you could scrap all teh stuff that is mostly unique to 77-78 and install an early valve cover with a vent tube.

1962-early 64 have a vented valve cover that feeds direct to front air cleaner and could be shunted to exterior. Late 64-67 have vented side cover that feeds through PCV valve into intake manifold. Your front sidecover possibly has a tube sticking out. Disconnect attached hose, plug hose opening in case air pump wants to make your mixture too lean (or remove airpump belt if not already disabled) run a new hose from that pipe on side of engine out where you can see it. Run engine and see if excess oil come out the hose, or if there is even any pressure on this at all (there will be a small amount of positive pressure, not vacuum) you can remove the cover and clean the attached oil separator and see if that helps. (hard to get at with exhaust in the way, but only one bolt holds it)
 
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