brakes help???

[colliemcc]

my brakes have been acting up the last few days..

While i am driving for awhile and using the brakes, they start to get really firm, until if you even tip the pedal and they come on, till eventually the front brakes start to stick and then i cant drive anymore... i then have to get out and open the nipple and a burst of fluid comes out...kind of go back to normal till the pressure builds up again..

i put a new brake master cylinder in about 4 months ago
and I've put two second brake equalisation valves on the rear a few weeks ago as it failed test on a brake imbalance on the rear.

any help would be greatly appreciated
Colm

 

[Andy_Mk3]

It sounds like you have a seized calliper. Take both callipers off (leave the hoses attatched) and push the pistons back. They should go right back without too much force. If one doesn't move or is very tight to move then you'll need a new calliper.

 

[Lefthooker]

not a completely seized caliper as if it was seized, releasing pressure would not unseize it. It would be stuck for good. (I know, this happened to me 4 weeks ago on my MK2!)
But it does sound caliper related. You dont want to be driving too much like that mate, you are overheating the discs and it wont take much time and they will warp. Even if they dont warp, they are probably trashed now. As are the pads, as they go glassy if over heated for a length of time.
As above, unscrew the calipers, remove the filler cap of the brake fluid resevoir and check the calipers for freedom of movement. If seized, get a new one on there.

Your goning to need to bleed the brakes after too. Also check the brake fluid level, if you keep opening the bleed nipple then you are gonna be low on that I think.

oh, what I wanted to ask ,, is it only 1 side, or both. If its both sides then I dont think it will be the calipers. Something else is preventing the return flow of brake fluid in the system. You might want to recheck the things you replaced. Something is not right there.

 

[jjwest]

They might be stickin mate have you re-greaced the calipiers as they do tend to dry up over the years there for causing them to stick is this happning on the bk aswell?

 

[jono_astra]

.

 

[colliemcc]

thanks for the replys.

As asked the both sides are seizing up. but not sure if the back are coming on as well i will check the next time it happens... is the brake servo different to a brake master cylinder???

 

[Andy_Mk3]

thanks for the replys.

As asked the both sides are seizing up. but not sure if the back are coming on as well i will check the next time it happens... is the brake servo different to a brake master cylinder???

The brake servo is the big black round thing, the master cylinder is bolted onto that with the brake pipes coming out of it

 

[colliemcc]

could the servo be the problem then.??

 

[tabetha]

tbh that sounds like a servo problem. not a caliper problem. you wouldnt get a solid brake pedal and then they stick. of your servo is buggering up then you can get the problem as you have described.

Exactly seen it lots of times, the one way valve in the servo jams and doesn't allow the pressure release, famous problem on certain bl cars.
Disconnect the servo pipe from the inlet and see what happens, brakes will be a bit heavier but nothing mental, but it will stop doing it.
tabetha

 

[jjwest]

sounds abit dangerous to me as you would have to stamp on them to stop or you saying tht to test them?

 

[Jordan_turbo]

sounds abit dangerous to me as you would have to stamp on them to stop or you saying tht to test them?

i think he means just do that to fault find

 

[colliemcc]

Exactly seen it lots of times, the one way valve in the servo jams and doesn't allow the pressure release, famous problem on certain bl cars.
Disconnect the servo pipe from the inlet and see what happens, brakes will be a bit heavier but nothing mental, but it will stop doing it.
tabetha

sorry could you explain a little more please.
thanks

 

[jjwest]

Good good as tht is well dodgy

 

[Jordan_turbo]

sorry could you explain a little more please.
thanks

at the back of the engine bay behind the brake fluid bottle there is the brake servo (a large round thing), it has a vacume pipe connecting it to somewhere on the inlet, its the vacume in the inlet that makes the brakes easier to push when the engine is running

go to somewhere quiet, disconnect the pipe i just mentioned and test the breaks. it will be harder to push the brakes (hense somewhere quiet) but hopfully you wont get the problem with the brakes getting stuck on

come back here with what you find out

 

[tabetha]

The brakes will of course be harder to push, but nothing ott, your average person will still be able to exert enough force on the pedal to lock the wheels just about, just you get a free workout!!
The problem is the valve in the servo, this opens as soon as the pedal is touched to allow the vacuum/suction to help push the rod in the master cylinder, but then on the return stroke it opens to allow the vacuum just used to be expelled to the atmosphere, and at the same closes off the vac channel inside the servo from the inlet.
On some older cars you could actualy hear the pssstt as you released the brake pedal.
tabetha