Welcome to our resource for MG Car Information.



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 - Clutch Master Cylinder Failure?

Need advice. MGB 1968- On several occasions, when coming to stop after attempting to gear down, gears lock up, engine seems to be pulling and the engine stalls. Cannot get gear into neutral or any other gear. Stuck in last gear shifted. Clutch pedal has no resistance (only hear the tension spring) After several attempts, finally goes into gear, clutch returns with pressure and gears change good along the highway. Come to the next stop, same thing happens. Checked fluid and holding good. Is this a faulty clutch master cylinder? Appreciate any help?

Eddie Haynes

just thoughts -

release arm?

master cylinder or seals?

when was the last time the gearbox oil was changed or even checked?


Nigel Atkins

Thanks for your thoughts. Since the pedal holds good with pressure until prolonged "pedal down" at stops, I think maybe the hydraulic fluid is leaking back around the seal and back into the reservoir of the clutch master cylinder. The cylinder appears to be the original one (how many rebuilds I do not know). I think I will go ahead and install a new complete clutch master cylinder to see if that corrects the problem.

Eddie Haynes

before doing that do a step by step logical diagnostics otherwise you could as many have done be replace parts unnecessarily and unfortunately many newly made parts are of poor quality or faulty so you could be replacing a good part with a bad part or replacing a part that doesn't solve the problem

plus you can look for signs and test your theory at home with the help of a glamorous assistant
Nigel Atkins

If you are not losing fluid then no pressure at the pedal for repeated operations has to be the master main seal failing. If on other occasions where it *does* release the clutch, but the clutch gradually engages by itself while the pedal is held down, then again it is the master main seal leaking back, but only slowly on that occasion. Difficult to see what more diagnosis can be done.
Paul Hunt

This thread was discussed between 07/07/2013 and 08/07/2013

MG MGB Technical index

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