Can anyone offer me some brake advice?
I've just put the brakes back together, which comprise discs on cortina uprights at the front and sierra discs at the back. I've put new
front solid brakes lines in and left the rears as they were. I also run a Ford (sierra I think) servo and master cylinder.
Try as I might I just can't get any pressure in the system. The brake pedal hits the floor. If you pump them you get a bit of pressure for 10
seconds or so, and then it's gone. The pedal actually gets stuck to the floor, at which point the brakes do come on a bit.
I've checked all my unions and I have no leaks. I've bled the system to death using several different methods and none of it makes any
difference.
I've had the master cylinder off and the seal between the servo piston and the resevoir looks fine. The only thing I can think of is that the
seals between the resevoir and the master cylinder have gone. I can't see any fluid leaking though, so when the pedal hits the floor where the
hell is the brake fluid going?
Any help much appreciated.
The symptons would suggest air in the system to be the almost certain issue here, how have you bled the system? do you have any high points in the
brake lines?
James
I've bled them using a a system that connects to the resevoir and runs of tire pressure, with a one-man, one way valve and traditional "someone holds the brake pedal down" methods. Fluid runs nice and clean with no bubbles. No real high points other than a loop in the front brake lines, the top of which is a few inches higher than the resevoir.
does sound like air but .....
you are gonna have to buy some bleed screws or make you own by soldering up an end of a brake pipe connected to brake fitting..
then disconnet all but one line screwing in the above nipples/blocked pipes, bleed and try the brakes.
if all is well, refit another brkae line and repeat to identify the bad line.,
incidentally, how are you bleeding the brakes?
the method I found that never fails is the 2-man method.
someone pressed on the brkae pedal, undo nipple, pedal will go downn, then do up nipple nad release brake pedal.
repeat this until no air bubb;les are seen.
preumably the pushrod/pedal allows the piston inside the ,aster to fully retract?
You do have the bleed nipples at the highest point also??
Not a bad idea. The rears are on the same circuit mind. I just don't see how there could be air in the system given how much I've bled them and the fact that I have no leaks.
I do yes.
quote:
Originally posted by Paul TigerB6
You do have the bleed nipples at the highest point also??
Don't waste your time bleeding the system ---
The symptoms only fit one thing a fluid leak - either external or internal within the mastercylinder back to the resevoir.
Start checking all your unions and nipples are tight.
[Edited on 4/4/09 by britishtrident]
I agree. I've checked all unions and nipples, which is why I think it must be the master cylinder/resevoir seals.
quote:
Originally posted by britishtrident
Don't waste your time bleeding the system ---
The symptoms only fit one thing a fluid leak - either external or internal within the mastercylinder back to the resevoir.
Start checking all your unions and nipples are tight.
[Edited on 4/4/09 by britishtrident]
Got to go and buy beer, but please keep posting until I get back if anyone has any other ideas!!
do as has been suggested ( check all unions are tight etc) then as its night time do the broom stick method, place broom stick onto brake pedal &
wedge it in place so as to keep the brake pedal depressed & leave over night, in the morning before removing broom stick undo one bleed nipple,
pref the highest furthest one from the master cylinder to release any air, tighten up again & remove broom stick, ensuring you have a full
resevoir of fluid before removing broom stick.
sometimes this works by keeping the system under pressure for a long time & any air in system will slowly collect at highest bleed point.
good luck & hth.
andy
I'll give that a go, many thanks.
my mate had simlar prob and he found that bthe rear nips was on the bottom of the calipar and that led to air catching at the top so he turned them
round and sorted it out
hope this may help
if there is a loop of pipe higher than ther reservoir then that "could" be an issue, but it sounds potentially more like the master cylinder seals might have turned over.
I'm now pretty sure it's the master cylinder seals. Anyone got a sierra master cylinder?