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MG Car Repair/Air pump leaking water


MGB Engine
MGB Engine  
Hi Barrie,

I am working on rebuilding my second MGB and its pretty close to a daily driver. However, I have noticed some water leaking from the air filter connected to the air pump for the emissions control system (see attached Pic).It not a lot of water but it is really muddy looking. Not sure if this is normal ?

My car is a 1976 MGB made for California, US. It was originally sold in LA and I'm the 3rd owner

Thanks in advance, really appreciate any help.

Hi Mark

It would appear that you have a leak on the suction side of the air pump.  

It could need a new hose (29) or a replacement restrictor valve (33), or it might be that the clips need tightening.

If this doesn't fix it, then I am concerned that the water is muddy.  
It is crankcase fumes that are being sucked out, not coolant water.  If they are heavily contaminated with rusty water, then this could indicate a head gasket failure, so I would also do a compression test on the engine, and a pressure test on the cooling system.

Let me know what you find.

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Barrie Jones


MG Sports Cars from 1949 to 1980 - Including MGB, MGBGT V8, TF1500, TF, TD and modern Midgets. I also specialise in SU carburettors, Lucas wiring, suspension, steering & brakes.


I have owned my 1955 TF1500 since 1966. Technical specialist for the TD and TF with the MG Car Club T Register. Also owned 20 MGBs and currently own an MGBGT V8. Written 3 books on MGs and produced a DVD on how to strip and rebuild the TD/TF gearbox.

MG Car Club.

Barrie's Notes on the 1953-55 MG TF (author). /=====/ Barrie's Notes on the MGB (author). /=====/ Barrie's Notes on the MGB GT V8 (author). /=====/ The Essential Buyer's Guide to the MG TD, TF and TF1500. (author)

M Phil, C Eng, BSc (Eng).

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