saph cossie brake problem, spongey pedal. help!!!

[robertthorpe]

Hi there, i have problem with my mates brakes, its a 1988 saph cossie, its a long story so hear gose......... Few months ago my mate had few corroded rear pipes, replaced them and did full system bleed, he drove it round for few months noooo troubles.......... Then few weeks ago he asked me to fit a set of coilovers and front bremsport calipers and discs i think they are 320mm or somthing. any way these were on my freind's car which he is breaking up and he recently had them overhauled with new pistons, ds2500 pads and discs. so i know they are fine!...... Before i did this HE fitted a external wastegate and exhaust manifold gaskets (he isnt the most mechanically minded person bearing in mind!) So fitted coilovers, then front brakes with the braided hoses that are made for the caliper, cleaned and greased all the pads up and usual stuff, fitted them no problems, no leaks. I decided to put ATE racing blue fluid in it, so drained out the whole system by leaving the nipples open for a few hours. Refilled the pot and did a full sytem bleed, all bled up fine, no air, no problems!!!! started it up pedal was perfect. BUT within about 10-15 pumps the pedal went shit, almost to the floor. sooooo bled the system again.......and again......and again (exactly as it says in the ford manual and the way i normally do it) first few pumps are perfect but as u keep pressure on it sinks to the floor , no air in the system, no leaks, accumulator pump is working fine and everything seems fine, all multiplugs in and correct. i checked every pipe, nipple, hose and must have bled at least 3 litres of fluid through it. Bearing in mind iam a mechanic and have worked on alot of these cars and own a 3-door myself which i did all brakes on last week and had no trouble with bleeding that in the exact same way with same fluid. and never had this problem before! If any one has any ideas or had this before, any ideas would be massively helpful!!! Thanks Rob

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[Ridgey]

I had similar and replaced the master cylinder, seems to have sorted it.

[robertthorpe]

its what i have been thinking tbh, just seems like master cylider valve stuck open or somthing to do with the valves inside that complex system, just so weird how its only just happened in time its been off the road only for 3 weeks...... :-/

[Ridgey]

Apparently the seals can be forced out of place (if that makes sense)!!! dunno if that was wrong with mine, not taken my old one apart yet to have a look.

[dojj]

youve got air in the valve bock

NEVER let the master cylinder resivour run empty or it will give you the problem you describe

you have to bleed the valve block by bleeding the return from the master clyinder to the blaock, but i can't remember now it's too late

[robertthorpe]

i did think about bleeding out the abs unit and pipes around the brake unit. probably worth a try. was a mistake letting it empty, sort of got distracted as it was draining out and forgot to tighten up the nipples. :-@ . if you remember which pipes would be a good help!
thanks
rob

[martysmartie]

As said above and it's a pain to remove, manuals etc refer you to Ford when this happens, although I would be interested to know if Dojj knows how (Not that I have ever had the need to though)

Martin

[dojj]

it's been a while but apparently the middle pipe from the abs unit and the valve block bleeds the exces pressure back to the accumilator so this owuld be the first port of call when bleeding is concerened

if you are changing the master then simply plug the pipes when you remove them to stop any possibility of this happening again

bleeding the system is effort but not money, changing the unit means youv'e got to find a decent quiality unit first of the right sort as there are 4 different types

[robertthorpe]

tried this this evening, had no luck with it....... any ideas where i go now??
thanks
rob

[Longshanks]

Daft question but I had similar problem a few years ago. Are you bleeding in the correct sequence..

[dojj]

ok, run this checklist and see what you've missed:

ignition to position 1 and bleed the rear brakes first, with foot on the pedal for person 1, rear brake nipple opened by perosn number 2 and person number 3 making sure there is fluid in the resivour?
repeat on the other side at the rear?
check the relays under the dash and, if it's a 4wd car, there is one in the fuse box as well?

[Longshanks]

Front left . Then front right , back left and you must finish on back right.. This is the proper sequence for cos bleeding

[Turbosystems]

the front brakes are bled with the ignition off and the accumulated pressure discharged
then bleed fronts conventionally with ignition off ie no abs pump
never ever drain the system completely

[robertthorpe]

Yeah i got the workshop manual as i wrote. So all been done properly and even used a pressure bleeder on it after the 20th attempt at bleeding. They are alot better than when i started this but still not quite right. Main problem was i found out mate had replaced one of the nipples on the caliper with the wrong one!!!!! So was drawing in air!
Thanks
Rob