Seized brakes

[flyer295]

My E type series 3 rebuild is now almost complete and due for the road. I have given it a pre MOT and found that the brakes are seized on.
Symptoms :-
Pedal can be pushed down without engine running (normal)
Pedal travels down when engine is started, as it should. (normal)
Pedal after that is rock solid. No play at all. (abnormal)
Initially I suspected the mechanical parts, the actual pads and calipers. Both are new.
I clamped off the flexi pipe on each wheel and opened the bleed valves. It works ok, and the wheel can be turned. BUT immediately I closed the bleed valve and released the clamp the pads became seized again. Obviously it is therefore a hydraulic fault keeping pressure in the line. BUT WHAT's causing it !!!!
The brake are so tight it's almost impossible to move the car, let alone drive it.
I did renew a leaking reaction valve some time ago and put the brake one way vacuum valve in the wrong way round initially as servo didn't appear to work. It does now.
Anyone any ideas ?

Bob

[abowie]

Check the reaction valve piston.

[madjack4]

Hi if reaction valve is free check u have all the vacuum pipes to master cylinder the correct way try disconnecting the pipes see if it still sticks on it sounds like something simple just need to find it

Regards Rob

[flyer295]

Hi if reaction valve is free check u have all the vacuum pipes to master cylinder the correct way try disconnecting the pipes see if it still sticks on it sounds like something simple just need to find it

Regards Rob

I've taken the diaphragm out. Is there supposed to be any fluid in the diaphragm ? I would have thought not, so possibly the reaction valve is leaking ? I've just checked the pipe runs and they are correct.
Bob

[mgcjag]

Hi Bob.....do you have a Jaguar service manual.....full detailed diagrams in there of the brake system.....a must have to understand the brake system...no you should not have fluid on the diaphram...you will probably need to check the resivac tank to see if fluid has collected there..This post may help and has diagram ......Steve http://forum.etypeuk.com/viewtopic.php? ... am#p105018

[flyer295]

Hi Bob.....do you have a Jaguar service manual.....full detailed diagrams in there of the brake system.....a must have to understand the brake system...no you should not have fluid on the diaphram...you will probably need to check the resicac to see if fluid has collected there..This post may help and has diagram ......Steve http://forum.etypeuk.com/viewtopic.php? ... am#p105018
[/quote

Hi Steve, Yes I do have a workshop manual but it doesn't seem to cover my problem. One thing that has occured to be, it and I quote, " when reassembling the item (34) Ensure that flex of diaphragm is correct way round" What is the right way round ? There is no diagram or description, and I did not take note of it when I removed the original, many months ago.
I have today removed the master cylinder, again showing a small amount very dark fluid on the inside of the diaphragm like rusty brake fluid. I took the small reaction valve out, cleaned it thoroughly and have replaced it. I'll try starting the engine prior to re-bleeding to see if that makes any affect, if not, then I'll re-bleed them only bleeding a system is a labourious job. Try that all tomorrow.
Bob

[mgcjag]

Hi Bob...the service manual has detailed drawings of the master cylinder including the diaphragm..