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MG MGB Technical - Pressure failure switch

Is it necessary to drain the brake master cylinder prior to replacing the pressure failure switch? From the manuals it seems so...I just wanted to confirm this prior to unscrewing it and spilling brake fluid all over the inner fender. Also if so is it best to bleed the system at the front and rear bleed screws or syphon it off? Thanks!
Frank

Sorry, I just checked the archives and apparently the switch is not subjected to brake fluid only the excess movement of the pistons which triggers it so apparently unscrewing it and replacing it should not be a problem. If there are different opinions out there please let me know. BTW mine is a 79.
Frank

Frank. Every one I have seen has tended to leak. There are a couple of O rings which are intended to keep the fluid from reaching the switch. These O rings wear over the years and fluid begins to drip through the switch and down the left inner fender. So, if you are not currently having a problem, you should not have a problem in changing the switch. Les
Les Bengtson

Thanks Les....no mine wasn't leaking as the master cylinder was almost brand new. I just partially dismanteled it while removing the brake servo vacuum line you guys helped me with earlier today. Your input is alway appreciated though. Thanks!
Frankl

This thread was discussed on 06/11/2002

MG MGB Technical index

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