Brakes nightmare.....

[geeman]

Hi all, i havnt posted on here in a long time but have been getting along well. The car is close enough to finished, just a few odd jobs to sort out. One thing that really has got me stumped though is the brakes. I just cant seem to get them to work well. I have bled and re bled many times, and even bought a pressurised bleeding kit which made the bleeding process much quicker. However, i cant seem to get the brakes to stop at all. Pressure only builds after around 30+ pumps of the pedal, and from what i have seen there dont seem to be any leaks. I did have to reflare one connection, but that was it, i havnt seen any other leaks, but yet no pressure builds. Any suggestions?

I dont imagine the master cylinder has any issues, as it worked well when it came out of the donor, but i may be wrong. Im using the standard rear sierra drums as well.

Thanks

[JakeH]

mechanic speak...:rolleyes:

seems to me like you have quite a bad pocket of air somewhere, seen this before and it can be a bugger to fix.

have you tryed bleeding the brakes from the furthest from the master cylinder first then next furthest and so on? (furthest being the longest run of brake pipe) this may cure your problem. if not im stumped!:o

EDIT: you could also try opening all the bleed nipples at once and leaving it to drip through for a bit, just be sure the reservoir is full all the time

hope this helps

Cheers

Jake

[geeman]

mechanic speak...:rolleyes:

seems to me like you have quite a bad pocket of air somewhere, seen this before and it can be a bugger to fix.

have you tryed bleeding the brakes from the furthest from the master cylinder first then next furthest and so on? (furthest being the longest run of brake pipe) this may cure your problem. if not im stumped!:o

EDIT: you could also try opening all the bleed nipples at once and leaving it to drip through for a bit, just be sure the reservoir is full all the time

hope this helps

Cheers

Jake

Hi, yep, have always bled in the logical ordar, furthest away first. Im happy to try anything that may get it to work at the moment.

I have now got through my first 4 litre can of fluid but Ill keep giving it a go and see what happens. One thing i notinced is when using the prussurised bleeding kit(20psi) once i finish bleeding but without having removed the kit, the brakes work relatively well and only take around 2-3 pumps of the pedal to get firm, however this would be expectd as it is pressurising it to 20psi.

Thanks.

[js1uk]

Sounds like the fluid is getting past the master cylinder plunger seals, so when you are pressing the pedal, it is not moving the brakes.

[mark]

Sound like master cylinder to me, quite a few m/c failures have arisen after they have been stripped from the donor and left dry for several months

[geeman]

Sound like master cylinder to me, quite a few m/c failures have arisen after they have been stripped from the donor and left dry for several months

I guess ill look around for a cheap master cylinder as it may well be the case its gone bad then, however i just noticed that when i pump the brakes for some time, i realised fluid was seeping out of the top of the resevoir, even when the lid is on as tight as i could get it. Any indications as to what the problem may be?

Thanks

[leroybrown911]

At risk of sounding stupid, have you got drum brakes on rear? Do you have some pedal? just not very good brakes?

If so the self adjusters may be worth a look. I have had similar issues on VWs. After fitting new pads, shoes and discs and bled the system, I had no pedal due to one self adjuster not moving as it should.

I am not familiar with Sierra drum brakes, however they are probably similar.

If this is the case, move the self adjuster manually with the drum off the car. Adjust it up so the drum fits just nicely over the shoes and then replace drum.

[flyerncle]

As above,remove the lip from the drum and click them up manually,clamp off the hoses and try it and also make sure the brake light switch is not vertical as this may give you a pocket of air.

It does sound like the seal may have gone bad with the fluid moving back and forth in the tank.

[geeman]

OK, after another day of trying to get the brakes to work i still havnt had much success. Firstly i tried what was suggested, and fistly, after moving the adjusters, for some reason,after a few pumps of the pedal it became reasonably stiff and only took about 2-3 pumps to fully lock the brakes. At this point i thought if i bleed them agan, i should end up with working brakes, so i went ahead and bled them, and a few air bubbles came out, however, now the brakes are back to what the were earlier, and the pedal can be pumped many many times before it gives much resistance at all.

I also angled the brake ligt sensor so its sideways, but that didnt seem to do anything. IM not sure tis the master cylinder that has a problem,a s at one point the brakes were reasonably stiff, however i may just buy another one to see if it helps as this is really becoming very frustrating.:mad:

[flyerncle]

Make sure the teeth on the ratchet's are ok and not slipping as they will return under spring pressure.

I have repaired them with a thread file many times.

[David_17]

I'm having exactly the same issues. Think i'm gonna try replacing the master cylinder next.

Is there was a simple way to test it?

[Enoch]

I had exactly the same issue on my car, replacing the master cylinder did the trick. My car had ABS so I had to source a m/c, I found one locally on ebay. When I first fitted it I found exactly the problem you describe. I stripped it, cleaned and used an old stock service kit, it is now fine. I think that the seals don't like to be exposed to air or something. I would suggest that it's a good idea to service a part that could well save your life anyway.
Enoch.

[Bonzo]

I would imagine the easiest way to test a master cylinder would be to blank the outlets off.

This could be done with the assistance of 3 suitable sized bleed nipples ( Don't tighten them too much as you will risk damaging the sealing faces in the mc )
You could also make up dummy brake pipes, very short & either solder the ends or crimp them a couple of times in the vice.

Provided that you have not trapped a massive amount of air in the master cylinder, if all is well with the master cylinder, the pedal should be rock hard when pressed.

As someone said, it is not uncommon for the master cylinders seals to fail after a long period in storage, I have personaly come accross this situation a number of times ;)

[snapper]

Had an issue with several master cylinders until I bought a new one.
I tested master cylinders 2 and 3 using bleed nipples in the 3 outlets, bleeding all 3 one at a time but never getting a firm pedal.
Tried the same with the new master, firm pedal and helps to bleed the master before attaching the pipes.
I put the first pipe on leaving bleed nipples in the other 2 ports, shortest pipe to the front and bleed till firm, then longer front, then single rear.
If you can't get a firm pedal when bleeding the rear, check the 3 or 4 way joiner, nip it up well, it often leaks a tiny bit, then bleed, nearest rear brake /shortest pipe to the joiner.
If there are issues at the rear you can use the bleed nipple method on the rear joiner.
Doing it this methodically will help you isolate a problem while having confidence in the previous work.

[geeman]

Well i tried what bonzo and snapper sugested this morning, and i couldnt get one of the pipes out of the m/c as i seem to have rounded off the connector at some point in the past(this was the one to the offside front caliper), however with bleed nipples in the other 2, i managed to get a firm pedal that i could no longer get to the floor, however it still did go quite a way. the offside front caliper did lock up as well.

Now, i connected the front nearside caliper, but the pedal now the pedal has no resistance and can be pumped many times with still no effect. this suggests something is up with the front n/s caliper i would think.

Ill give it a go to see if i can get a firm pedal with just the rear and offside calipers connected. Thanks

[geeman]

some good news, with the front offfside and rear brakes attached to the m/c, and the front nearside blocked off, i am getting a very hard pedal after about 2 pumps of the pedal, which suggests just some trapped air somewhere, however when the front nearside is connected, i can pump forever, so something must be up with that caliper, any ideas as to what could go wrong with the caliper? Thanks