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Discussion Starter · #1 ·
I replaced the front brake calliper seals and piston due to an issue with one of the brakes, the RAC rescue guy said the front calliper had ceased and needed looking at!
I rebuilt the calliper and cleaned them up, the replacement pistons are Stainless steel (chrome-plated), Vauxhall would sell replacement Phenolic pistons, they would only sell me the complete calliper, which was out of my budget sadly, it may have made life a lot easier. I bled the brakes, the pedal did firm up, but as soon at the car started all the pressure went out of the pedal and they had no resistance to them. I bled them again and again, and exactly the same outcome.
I took it to a local guy that repairs cars, and he bled the brakes, several times, and again he had the same outcome!
I took it to a local garage and he attempted to bleed the brakes and he had the same issue, he said he tested the system for leaks, and the system was ok , no leaks. We decided at this point to replace the master cylinder with an aftermarket unit, the garage mechanic fitted this and tried to bleed the system once again, and the same outcome!
I decided to replace the seals and check for any damage or obvious signs of a leak or issue, to be honest, I couldn't see anything, i contacted the supplier of the aftermarket pistons and seals, and asked for another set of seals, which he sent, and I fitted these and tried bleeding the brakes again, a fair amount of ait was in the system, I bled the brakes until no sign of air etc.. the brake pedal firmed up again as before, as soon as we started the car, the pressure left the system.
I did clamp off the flexible hoses to both front brake callipers, and the pressure was solid, leaving me to assume that it is something to do with one or both callipers!
I took off each clamp one at a time and the brakes became spongy and when started the engine the pressure left the system, could this be something to do with the ABS?.
I can only guess at the problems now, no fluid is passing out any of the seals, but I am guessing that air can still pass the seals into the system, should there be a seating issue? but this is pure conjecture on my part! I am clutching at straws..
Any ideas or suggestions would be most welcome at this point. I am considering putting the original Phenolic pistons back in with the original seals, just to see how these respond to bleeding, but because of some external damage to the original pistons, I would prefer to replace them with new ones.
My next step, which will be expensive, is to buy 2 new callipers and fit them, but I wanted to be sure that it is the pistons or seals that is the issue, before outlaying a fair chunk of cash I don't really have to spend!
Has anyone had anything similar or has any ideas, thoughts or suggestions at this point? Thanks for reading this novel.
 

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I replaced the front brake calliper seals and piston due to an issue with one of the brakes, the RAC rescue guy said the front calliper had ceased and needed looking at!
I rebuilt the calliper and cleaned them up, the replacement pistons are Stainless steel (chrome-plated), Vauxhall would sell replacement Phenolic pistons, they would only sell me the complete calliper, which was out of my budget sadly, it may have made life a lot easier. I bled the brakes, the pedal did firm up, but as soon at the car started all the pressure went out of the pedal and they had no resistance to them. I bled them again and again, and exactly the same outcome.
I took it to a local guy that repairs cars, and he bled the brakes, several times, and again he had the same outcome!
I took it to a local garage and he attempted to bleed the brakes and he had the same issue, he said he tested the system for leaks, and the system was ok , no leaks. We decided at this point to replace the master cylinder with an aftermarket unit, the garage mechanic fitted this and tried to bleed the system once again, and the same outcome!
I decided to replace the seals and check for any damage or obvious signs of a leak or issue, to be honest, I couldn't see anything, i contacted the supplier of the aftermarket pistons and seals, and asked for another set of seals, which he sent, and I fitted these and tried bleeding the brakes again, a fair amount of ait was in the system, I bled the brakes until no sign of air etc.. the brake pedal firmed up again as before, as soon as we started the car, the pressure left the system.
I did clamp off the flexible hoses to both front brake callipers, and the pressure was solid, leaving me to assume that it is something to do with one or both callipers!
I took off each clamp one at a time and the brakes became spongy and when started the engine the pressure left the system, could this be something to do with the ABS?.
I can only guess at the problems now, no fluid is passing out any of the seals, but I am guessing that air can still pass the seals into the system, should there be a seating issue? but this is pure conjecture on my part! I am clutching at straws..
Any ideas or suggestions would be most welcome at this point. I am considering putting the original Phenolic pistons back in with the original seals, just to see how these respond to bleeding, but because of some external damage to the original pistons, I would prefer to replace them with new ones.
My next step, which will be expensive, is to buy 2 new callipers and fit them, but I wanted to be sure that it is the pistons or seals that is the issue, before outlaying a fair chunk of cash I don't really have to spend!
Has anyone had anything similar or has any ideas, thoughts or suggestions at this point? Thanks for reading this novel.
Hey Pal. When yoy are bleeding the brakes ate you doing it the manual way or using a brake bleeder?

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Discussion Starter · #3 ·
Sorry about some of the typos and grammar. just so this makes a little more sense, "the Vauxhall dealership would not sell just the calliper pistons and seals".
Is there a relationship between the brake pressure in the braking system and the engine, that could or would affect a change in pressure when the car starts?
I may have bitten off more than I can chew here, to take it to a garage and ask them to just sort this issue, could cost a fair chunk of cash, because everyone mechanic I have spoken with said they will only fit new genuine Vauxhall parts, and I can totally understand. why!
Anyways, I not going to go on any more, I look forward to your input.
Thanks
 

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I have tried both ways, and so did th mechanic at the garage.
A swering this and abit of your other post. Im a little unsure why mechanics would only fit genuiune parts. You could get an aftermarket brake caliper and should be fine as long as it is a decent level part. The brake system is hydraulic driven from what im aware of. When car is imoff and u pump brakes it should go really hard and then if you press and hold the brake pedal and then turn on the car as your doing so you should steadily feel your foot go down meaning your brake booster is working. If that checks out i cant think what the issue maybe. If you werent using a proper brake bleeder i.e it can provide a constant stream of fluid via pressuring the bleeder i w9uod invest in one of those

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Discussion Starter · #6 ·
I have a brake bleeder that constantly feeds fluid under pressure, i am assuming this is what you mean?
I get the impression from most of the garages we contacted are concerned about any come back if using non-genuine parts, I agree, there are some good quality aftermarket parts available that are of high quality, but the ones I have spoken to won't fit anything other than genuine parts!
Thanks for explaining about the booster,
 

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I have a brake bleeder that constantly feeds fluid under pressure, i am assuming this is what you mean?
I get the impression from most of the garages we contacted are concerned about any come back if using non-genuine parts, I agree, there are some good quality aftermarket parts available that are of high quality, but the ones I have spoken to won't fit anything other than genuine parts!
Thanks for explaining about the booster,
Well i undestand your worry of going oem calipers as they wipl be pricey. But i wpuld consider doing 9t yourself with decent grade aftermarkets. Or if your willi g ask you garage to fit aftermarket and say you willing to sign something acknowledging you won't hold them liable should this not resolve the problen but pbviouspy not waving the right if the caliper happened to just be faulty in generap anyway.

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Discussion Starter · #8 ·
yes, its might be worth fitting good quality aftermarket callipers, I could ask about signing a waiver for the garage, and see what they say. getting replacement callipers before Xmas break may be difficult, I will go ask at a local supplier tomorrow.
This has been going on for a few weeks now and not having the car is causing difficulty, I need to get it sorted :)
Thanks for posting your thoughts and ideas!
Cheers
 

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yes, its might be worth fitting good quality aftermarket callipers, I could ask about signing a waiver for the garage, and see what they say. getting replacement callipers before Xmas break may be difficult, I will go ask at a local supplier tomorrow.
This has been going on for a few weeks now and not having the car is causing difficulty, I need to get it sorted :)
Thanks for posting your thoughts and ideas!
Cheers
Hey Andy just seeing how you got on in the end with this whole issue?

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