I'm pulling my hair out over my brakes! I've fitted mondeo calipers and st170 discs to the front and cossy 2wd rear discs and calipers, all with braided lines and new fluid to my 88 xr3i. Now ive bled the system through about 6 times now and pedal still goes straight to the floor! is there any way i can test if i have air in my master cylinder or if my master cylinder or servo is knackered? The brakes worked fine before and i only removed them to upgrade so im sure its air in the system? HELP! im at the point where i just want to smash the thing to bits!

 

Are you bleeding them in the correct order? Ie furthest away from master cylinder first? Then working forward that way? I had bother by not doing this procedure once

 

Yea. i started o/s rear, then n/s rear, then o/s front then n/s front. my master cylinder has 4 lines coming from it so i would assume 1 per corner. Ive googled it and a few i have seen have only 2 lines coming from them? Ive tried bleeding with a mate depressing the pedal and i also bought a easy-bleed from halfrauds but still foot to the floor. if i pump the pedal it goes hard and will stop the car?

 

If you are just topping the resovoir up and pumping the pedal this may be the problem. I had to use a pressure system like Easi Bleed which uses air pressure from a spare tyre to force fluid into the system and the air out.

 

Tried that. Every time i bleed it im just getting fluid. no air? im not sure if air can get trapped in the M/C?

 

Clamp off each flexi in turn (mole grips + card wrapped around the pipe if you have no proper pipe clamps) and see if the pedal improves.

 

Makes no odds what order you do it in IME, most likely is all that pumping to the floor has fucked the master seals, i only ever use an easybleed on old master cylinders
All the years of a short travel wears the master bore then somone stamps on the pedal and the ridge at the end of the wear area nips the tipas of the seals off ?
Not a deffo but a high possability, you can't clamp off to test if you have braided hoses
It could be all the new piston sizes are too large for old master to move enough fluid but if it's a tried and tested setup i doubt it ?

 

Just sounds like the master cylinder has gave up quite common after bleeding brakes!

 

I recently had this on my mk4 golf, people were telling me it was the master cyclinder.

It wasn't though. Below my fluid reservoir there are 2 bleed nipples,
I bleed the master cylinder via the 2 nipples and the pedal came back.

You may have let the level fall to low and now have an air lock in the master cylinder.
Check to see if you have bleed nipples on the master cylinder and try bleeding it from there



Also not sure if its possible on your car, but have you got the calipers up the right way? i.e bleed nipples at the top,
Ive heard of people fitting the wrong caliper to the wrong side of the car with the bleed nipples at the bottom, this would also make it impossible to expel trapped air from the system

 

yer just done this to mine same problems as your haveing, found the mater syinders on back were fuked, also the when i changed them, found that the servo was also dead had been stood around for 3 years though hope this helps

 

would the master cylinder just let go? i'd of thought it would of just got progressively worse? My first thought was air in the M/C so ive tried bleeding it but im not sure if ive been doing it correctly? ive been getting a friend to pump the pedal a few times then hold it down while i crack off a brake line until it weeps fluid. then repeating it for all 4 lines. is this the right way of doing it or is there another/better method?
thanks for the comments so far guys, ive already had to cancel my day on the rollers once because of it. I just want to use the bloody thing!!

 

seals in the cylinder being fucked would be high on my list

but secondly, i'd be looking to get at least the mk3 mondeo servo and m/c assembly fitted to give you the same amount of fluid capacipty and travel to fill the calipers up fully

you may just be experiencing the case of your little master cylinder simply not having the capacity to move so much fluid through the system for the calipers you've fitted

 

May just be the way you've worded it but it doesnt read right to me.

Fill a milk bottle (or similar) up with brake fluid 1/4 full.

Get a piece of hose (clears best so you can see air bubbles more easily).

Put one end of hose on your bleed nipple and one end emerged in the brake fluid. Making sure it's emerged through out.

Slack nipple off and then get your mate to pump the pedal (making sure your reservoir is topped up constantly) and watch for air leaving the system in the brake fluid.

Once your happy all the air has left get your mate to hold the pedal down and nip the nipple back up. Repeat as necessary on each corner.

If this is the procedure you've been using then my mistake and you should probably look at the master cylinder - try a second hand unit.

This is how i've always done it and never had any problems (yet)

 

I probably should of made it clearer. above is how i tried bleeding the master cylinder. To bleed the lines ive used the method :henniker: has described. Is there any other ways of bleeding a M/C?
Thanks again for any replies, i know this isn't the most interesting post!

 

pump the pedal up, after 5 or 6 pumps, keep the pedal on the floor and open the nipple till the pedal sink, then nip up the nipple, making sure that the pedal stays depressed while the nipple is open

 

Starting from the master cylinder crack off each union in turn along the paths on each brake line. You can sometimes find an airlock type situation that is only resolved by doing this, you will see bubbles coming out from the unions. Work you way to the back of the car.

If the car has any load sensors make sure you have it on it's wheels when bleeding, otherwise you won't be able to bleed the rears.

 

*update*
So after reading all your replies i have replaced the master cylinder...no difference.. re-bled the master cylinder twice and re-bled all 4 lines several times...no difference. Then i was concerned i had air getting into the system so i pressurized and went around to every joint/connection with a squirty bottle with fairy liquid....no leaks. My next thought was that the master cylinder was not man enough to move 4 pistons, so i blanked off the 2 rear lines at the master cylinder, re_bled front 2 lines....no difference!
ive got to the point now where i could cry! i cannot for the life of me think what else it could be?? the only part of the system i havent touched is the servo? what are the signs of a failed servo? i always thought the pedal would go hard not the opposite? please help!

 

without pointing out the obvious, you have connected the rear lines to the rear output and the fornt ones to the front output yes?
if they are the other way around they won't work, or will be shit

any chance of some pics of your master cylinder and servo setup?

the servo might have suffered after the last m/c but it makes no difference when it's not being pumped by the engine vacuum

 

Is new mastercylinder a xr3 one?

 

its exact replacement. 88 xr3i one

 

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the blanked off two are the rears

 

every time i've tested it the engines been running... any help gratefully received!

 

so does everythign bleed properly?
as in when you press the pedal fluid comes out of hte calipers and there is a build up of resistance?

 

i would reconect the rears and bleed the system if you still have no pedal, then i would clamp offf all 4 flexi hoses and see what that does for you mate, personally i think the mastercylinder is too small?

 

yea, pushes fluid through no problem.

i cant clamp the flexis cos they're braided!? surely the master cylinder would be man enough to work just the front two pistons? but theyre just as poor with the rears disconnected?

 

had the same setup on mine with no issues.

but with the standard master cylinder on a turbo tho.

 

What condition are the pads in?

If they have any wear on them, remove them and jam wood or steel plate inbetween the disc and piston, forcing the piston fully in.

Wind the back pistons fully in and jam with spacers the same, then bleed.

 

everythings new. will this prove a faulty caliper?

 

You have got the rear wheels on the ground for the load sensing valves to let fluid past? It was mentioned above but I don't think it was clarified?

 

When you upgrade to st170 discs and calipers on just the front you will lose pedal or only get half if you get what I mean and the fact you got a disc set up at the rear will again make it worse due to the amount of fluid required to move the pistons. It is recommened that you use a mk1 mondeo master cylinder and servo combo to over come this problem. The mk4 escort m/c servo just simply isn't up to the job.

 

Back to the very basic here... Are the bleed nipples at the highest point possible when you are bleeding? If not, then you might still have air in the calipers.

 

Yep all bleed nipples as they should be

no load sensors on my 3i but the wheels go back on the ground everytime to test it

with regards to the master cylinder not being man enough to move 4 pistons, would blanking off the rears at least give me some pedal back? at least half pedal?

thanks for the replies guys

i seem to have been over the fluid side of things several times, i havent looked at the servo yet. is there any signs or ways to prove a faulty servo?

 

Disconnecting the rears won't make any difference, the front and rear circuits are completely separate, if you look at the bottom of the reservoir, where it connects to the master cylinder you can see this. Fronts work off the front section and rears work off the rear section.

 

master cylinder isn't up to the job, blanking the rears wont help as there is 2 pistons in the master and blanking the rears just means that 1 isn't doing anything, the other is still trying to fill 2 bigger calipers, get a mondeo master cylinder,
i've had the same prob with a fiesta turbo, couldn't get a decent peddle after we upgraded the front brakes, bigger master and all was well again

 

As the last reply and mine mate you are wasting your time until you get a mondeo master cylinder and servo mate

 

I have 2wd calipers on the rear and AP 4 pots on the front with a standard master cylinder and the pedal is spot on.

If your car is piped up as a standard car that left the factory then you have actually blanked off a front and an opposing rear caliper. Standard cars had the passenger side of the master working the fronts and the drivers side of the master working the rears. IT IS IMPORTANT THAT IT IS PIPED UP THIS WAY!!! You will never get a good pedal unless it is piped up so that each chamber of the cylinder works 1 front and 1 rear caliper each!

I recently had an issue where I had no pedal unless you pumped it, then when you lift off it would go. Nothing but fluid would come out on bleeding them but the issue turned out to be a tiny pocket of air trapped in the rear calipers. I had to unbolt the bottom caliper slides an twist the caliper to point the nipple upwards to get rid of it.

 

It's not the servo. That will just make the pedal heavy if it fails.

Just a further point to clarify my post above. The rear 2 ports on the master is 1 chamber and the front 2 ports are the other chamber. These chambers must work 1 front and 1 rear EACH so that the displacement produced is equal from each chamber and you get balanced effort.

 

When you bleed the back you need to unbolt the caliper and move it round the disc so the bleed nipple is the highest point. Then bleed then bolt back on.

 

Might sound stupid but, is the handbrake on?

Thanks,
Tom