Over the winter I seem to have developed a leak from the brake master cylinder. Looking towards the cylinder from the footwear I can see a rubber o ring which isn't completely seated but am unsure whether this is the culprit and whether simple reinstatement will resolve the problem. The brake fluid sees to have been leaking from the pedal side of the cylinder dripping down onto the floor belo. There hasn't been any fluid in the footwear nor at the opposite end of the cylinder.

I've disconnected everything and am cleaning and attending to any corrosion issues

3 questions. How has this happened and how do I prevent it from happening again. Lastly what's the best way of getting back on the road for a summer of fun motoring - servuce kit, buy a replacement, service exchange or other?

Wouldn't expect to see an O ring. Is it the dust cover you're seeing? If so that won't be the source of your leak. That can only be the pressure seals and there's no way to see those without stripping the cylinder.

Solutions are...
New seals providing the bore is OK (not pitted) and they're available Or...
Replacement master cylinder.

Do you know what cylinder it is?

Looking on ebay it looks like it's from a 2.8

I'm in the process of sorting my brakes and as I was passing I called into a company in Bury St Edmunds (Past Parts)
for a quote, just in case it turns out that I need it.

Mine is a tandem M/C, I think from a Cortina, and he said seals would be between £8 & £15 if I did the work,
£70 if they re-furb'ed it, and worst case scenario, £140 if they bore it out and put in a stainless sleeve.


I know you probably don't need this but I thought it might be useful info anyway.

Cheers
Paul G

It might have some numbers stamper on it somewhere that'd let you trace it. To be sure what it is otherwise you'd need to know the bore size.

Is your brake take a lot of pressure/hard; Often are using master cylinders from cars that had servos fitted. Alternative would be to swap to a smaller size master (from a car without servo - Fiesta/Uno) would give you a lighter pedal.

I once needed a master cylinder for an old Alfa that even 15 years ago was obsolete after spending ages ringing around I was put in touch with a guy that had a new old stock item, he wanted £600 plus VAT , his attitude was I've got one , you need one, that's the price take it or leave it . Past Parts reserved and reconditioned the old one for £ 95 inc VAT and postage . Up until last year it still worked when the car passed to a new owner . AFAIK the guy with the £600 item still has it after I let a fewAlfa specialists the tried to help me were informed of PP . For old obsolete parts they are very helpful and prices are reasonable. If your master cylinder is leaking get it sorted properly