Bleeding brakes
Discussion
This is a follow on from my other thread here.
https://www.pistonheads.com/gassing/topic.asp?h=0&...
The repair to the brake line went fairly simply like I thought it would but as for bleeding them they are a right pain in the arse.
When it first happened I told my mate to go out and buy some brake fluid and keep it topped up because I know if air gets into the ABS module it can be a right so to sort out but he couldn't be arsed and let it all leak away. We tried the pumping method with a tube and a glass jar with fluid in, and whist we did get the air out and fluid into the jar from each wheel we just can't get a solid pedal, there doesn't seem to be much pressure at all at the wheels, especially the rear ones.
We actually changed the master cylinder for one of ebay in case the seals had been damaged when it originally happened but this one is doing exactly the same as the old one.
I've had all the unions off at the ABS module, the two incomers and 4 outgoing pipes and there is fluid at all of them there just doesn't seem to be any pressure really, will a pressure bleeder make any difference to bleeding the brakes, something like this.
https://www.amazon.co.uk/Sealey-VS820-Clutch-Bleed...
If the above does work, this might be a daft question but are all reservoir caps a standard size and what are the chances of this fitting on the reservoir cap?
I know people will say take it to a garage, its the brakes, life or death etc but I'm determined to fix this one by myself so will take no notice of those sort of comments, sorry.
Edit to add, we changed a rear caliper on the same car a couple of years ago and that was very straight forward, screwed the line into the caliper, bolted it on to the car, undid the brake line, a few pumps and all the air was out and fluid flowed into the jar and the brakes worked fine, not sure why its so difficult now.
https://www.pistonheads.com/gassing/topic.asp?h=0&...
The repair to the brake line went fairly simply like I thought it would but as for bleeding them they are a right pain in the arse.
When it first happened I told my mate to go out and buy some brake fluid and keep it topped up because I know if air gets into the ABS module it can be a right so to sort out but he couldn't be arsed and let it all leak away. We tried the pumping method with a tube and a glass jar with fluid in, and whist we did get the air out and fluid into the jar from each wheel we just can't get a solid pedal, there doesn't seem to be much pressure at all at the wheels, especially the rear ones.
We actually changed the master cylinder for one of ebay in case the seals had been damaged when it originally happened but this one is doing exactly the same as the old one.
I've had all the unions off at the ABS module, the two incomers and 4 outgoing pipes and there is fluid at all of them there just doesn't seem to be any pressure really, will a pressure bleeder make any difference to bleeding the brakes, something like this.
https://www.amazon.co.uk/Sealey-VS820-Clutch-Bleed...
If the above does work, this might be a daft question but are all reservoir caps a standard size and what are the chances of this fitting on the reservoir cap?
I know people will say take it to a garage, its the brakes, life or death etc but I'm determined to fix this one by myself so will take no notice of those sort of comments, sorry.
Edit to add, we changed a rear caliper on the same car a couple of years ago and that was very straight forward, screwed the line into the caliper, bolted it on to the car, undid the brake line, a few pumps and all the air was out and fluid flowed into the jar and the brakes worked fine, not sure why its so difficult now.
Edited by scottyp123 on Monday 31st August 17:06
scottyp123 said:
If the above does work, this might be a daft question but are all reservoir caps a standard size and what are the chances of this fitting on the reservoir cap?
No they aren't all the same size - for example my wife Kia doesn't even have a cap you screw on, it's like a bayonet style fitting style - but there is a more common set of sizes it should work with out of the box.A pressure bleeder is very handy, and can sometimes be used in situations where bleeding "manually" wont cut it - but I don't think this is your real problem.
Is it possible to bleed the master cylinder? Do you have the diagnostic gear to bleed the ABS pump?
I don't want to be disparaging but I think your a little out of your depth here.
I'm very happy working on brakes, fluid, rebuilding calipers etc but for brake pipes I've let a garage do it.
Not sure why you're starting a whole new thread for this.
If you aren't getting pressure at the master cylinder outlet then either there's air in the master cylinder, or it's faulty. It's pointless speculating about ABS systems until you have pressure at the m/c.
If you've taken that off at any point make sure that the adjuster on the pushrod is not too tight. The piston needs to retract fully to let fluid into the circuit. If the piston is gummed up so that it doesn't retract full, or the pushrod is too tight so that it can't, the reservoir will never be open to the circuit so you will be left with an air pocket on the downstream side of the piston.
If you aren't getting pressure at the master cylinder outlet then either there's air in the master cylinder, or it's faulty. It's pointless speculating about ABS systems until you have pressure at the m/c.
If you've taken that off at any point make sure that the adjuster on the pushrod is not too tight. The piston needs to retract fully to let fluid into the circuit. If the piston is gummed up so that it doesn't retract full, or the pushrod is too tight so that it can't, the reservoir will never be open to the circuit so you will be left with an air pocket on the downstream side of the piston.
GreenV8S said:
Not sure why you're starting a whole new thread for this.
If you aren't getting pressure at the master cylinder outlet then either there's air in the master cylinder, or it's faulty. It's pointless speculating about ABS systems until you have pressure at the m/c.
If you've taken that off at any point make sure that the adjuster on the pushrod is not too tight. The piston needs to retract fully to let fluid into the circuit. If the piston is gummed up so that it doesn't retract full, or the pushrod is too tight so that it can't, the reservoir will never be open to the circuit so you will be left with an air pocket on the downstream side of the piston.
I am inclined to think its the master cylinder, how would you check for pressure at the master cylinder though, before I changed the master cylinder I unscrewed the two main feed pipes that came from the master cylinder from the ABS module and when pumping the pedal you could keep your finger over the end of the pipe that did the rear brake set, I would expect the pressure to push your finger away if the master cylinder was working. That's why we changed it but it hasn't really made any difference.If you aren't getting pressure at the master cylinder outlet then either there's air in the master cylinder, or it's faulty. It's pointless speculating about ABS systems until you have pressure at the m/c.
If you've taken that off at any point make sure that the adjuster on the pushrod is not too tight. The piston needs to retract fully to let fluid into the circuit. If the piston is gummed up so that it doesn't retract full, or the pushrod is too tight so that it can't, the reservoir will never be open to the circuit so you will be left with an air pocket on the downstream side of the piston.
scottyp123 said:
how would you check for pressure at the master cylinder though
If it's working the pressure will be very high and immediately obvious if you try to block off the outlet while somebody pressure the pedal down. Not working implies no seals or no fluid on the downstream side of the piston.I suspect the only way you will get a pedal back after what your mate did is to combine the use of a pressure bleeder & the old 2 man method.
Tell him he is a right royal @rse first though.
Pressurise the reservoir from the pressure bleeder, press down the pedal, and only then release the bleed nipple, rinse repeat.
Tell him he is a right royal @rse first though.
Pressurise the reservoir from the pressure bleeder, press down the pedal, and only then release the bleed nipple, rinse repeat.
Get a second hand factory MC reservoir cap, drill it for a fitting (barb) to take the pressure bleeder pipe, then after screw on your original cap.
(I found the caps fitted in the kits are usually s
t quality and when you use double the recommended air pressure to speed things up, the cap blows off into the heavens covering everything in fluid.) Not so if you drill a factory cap..
(I found the caps fitted in the kits are usually s
t quality and when you use double the recommended air pressure to speed things up, the cap blows off into the heavens covering everything in fluid.) Not so if you drill a factory cap..
We've finally got the brakes back. I ordered the Sealey pressure bleeder from Amazon the other day and after a bit of a palava from Amazon it finally turned up last night. Even using this though it was still really hard to get the fluid flowing down the lines, it didn't seem to matter whether the engine was running or not really to get it working.
The only way it seemed to work in the end was the way posted by someone earlier and that is to both pressurise the lines up and pump the pedal as well and even then I had to crank the pressure up to about 30 psi to get it flowing. In the end plenty of air and fluid came out of the bleed nipples and the pedal is now back to normal.
However other problems have materialised as well. The check engine light is now on although this could be just a coincidence but the biggest concern is the ABS and TC lights are on along with a warning on the dash. (the engine light was on before these two). What happened was whilst the car was on 4 stands and all the wheels off we tested to see if there was any braking force at all at the rear wheels by putting the car in gear and revving the engine whilst braking. The car didn't seem to like this and immediately activated the TC and removed the throttle so I turned off the TC manually with the button and the car revved again. Since doing this though the 2 lights have been on permanently.
Its possible we have damaged an ABS sensor messing about with the bleed nipples, they have certainly been undone and tightened enough times in the last two weeks. I have also tried the steering wheel trick where you turn it lock to lock to re-set it but it made no difference.
The only way it seemed to work in the end was the way posted by someone earlier and that is to both pressurise the lines up and pump the pedal as well and even then I had to crank the pressure up to about 30 psi to get it flowing. In the end plenty of air and fluid came out of the bleed nipples and the pedal is now back to normal.
However other problems have materialised as well. The check engine light is now on although this could be just a coincidence but the biggest concern is the ABS and TC lights are on along with a warning on the dash. (the engine light was on before these two). What happened was whilst the car was on 4 stands and all the wheels off we tested to see if there was any braking force at all at the rear wheels by putting the car in gear and revving the engine whilst braking. The car didn't seem to like this and immediately activated the TC and removed the throttle so I turned off the TC manually with the button and the car revved again. Since doing this though the 2 lights have been on permanently.
Its possible we have damaged an ABS sensor messing about with the bleed nipples, they have certainly been undone and tightened enough times in the last two weeks. I have also tried the steering wheel trick where you turn it lock to lock to re-set it but it made no difference.
GreenV8S said:
More likely you have frightened the ECU by unexpected combinations of wheel speeds and accelerating and braking and so on, so it has guessed there is a fault.
I guess so but you would think it would work everything out after a drive round town but its still stubbornly on. Gassing Station | Home Mechanics | Top of Page | What's New | My Stuff