Brake bleed woes

[Raistlin]

Hopefully somebody can help with this please?

After a successful servo and master cylinder transplant, the car concerned refuses to bleed properly. We can get a reasonably firm pedal but it is almost on the floor.

The car is a post face-lift S-Type diesel with the servo that has the two extra electrical connections.

Any ideas gratefully received please

[Budgie]

Hello Paul,

Rather odd symptoms you appear to have and no immediate cause comes to mind I have to say. Were the donor parts used or new?

Although you probably have this I've included the Braking Fault diagnosis section of the Workshop Manual for your perusal.

Hope it's of help.

 

Braking.pdf

[JOE-DOT-COM]

hi

also are you sure the servo is good

there dual circuits, and if one fails the second set of seals inside the master cylinder is suppose to work, which is usually with a very low pedal position

its either got air in or you might have a faulty servo, was it new or used

cheers

Joe

[Raistlin]

Thanks chaps. We've tried three servos and three master cylinders. Same smptoms each time.

Thanks for the diagnosis Brian.

[Raistlin]

Solved

Having acquired a vacuum brake bleeding tool, we set about the bleeding process from square one. ie. near-side rear.

I have NEVER seen so much air in brake fluid. The stuff being drawn out under vacuum was so gassy it looked like milk.

The same thing happened with the other three calipers but as a result, the car now has perfect brakes.

Highly recommend the vacuum brake bleeding kits.

[Budgie]

Hi Paul,

I do like a happy ending (and of course compliant brakes) 

I bet you're relieved

Cheers

Brian

[JOE-DOT-COM]

hi paul

I've used a vacuum hand pump for years, I have a mityvac but copies are available for less than £15 now

there great your can bleed brakes and clutch, one man, no need for anybody to press the brake pedal

they work especially well on motorcycles as the master cylinder move so little fluid it can take forever to bleed them

cheers

joe