Rear Brake leak

U

Un4tural

Member
Hi All,

Had a look today and following pads/disks replacement leak had gotten A LOT worse, seems to flow freely but it is neither the joints where brake line comes in nor the bleed valve.

It seems to drop over the hand brake cable and the lil bracket that holds hand brake cable, can't tell where it is coming from exactly.

Just wanted to make sure it is safe to assume it to be brake cylinder before i start ordering bits and to check what bits i need to order? how does the actual piston sit in the housing? did not look like i could press it out so would i need to get housing with caliper pre-assembled? Looking something like what is listed here i guess?

https://www.onlinecarparts.co.uk/oenumber/6q0615424a.html / https://www.ebay.co.uk/itm/VW-POLO-...813187&hash=item365b8e75d4:g:s2UAAOSwJPxeHGEA

https://audi.7zap.com/en/rdw/audi+a2/a2/2003-248/6/615-615060/

it is rear left corner, now it looks almost like it is just leaking freely when pressing brake pedal... drops over the lil nib at end of hand brake cable and the bracket with spring holding hand brake cable.
 
The cylinder normally makes the inside of the wheel wet with fluid and leaks out the bottom of the drum for drum brakes. As you have a 90 it has rear discs so there is no cylinder to speak of, just the caliper itself. Jack the car up and secure it. Take the wheel off, release the hand brake and while someone operates the brakes with the engine running have a good look around at the caliper and brake pipes. Check the bleed valve is not leaking. If the leak is that bad you should see it spray out or at least flow out. Good chance when the piston was retracted into the caliper there was some rust that has become further trapped in the seal. May need to reseal or replace the caliper unless you find an external source of leakage.
 
Sorry unsure on the names of bits - but assuming it is piston bleeding just would've thought it'd be more front side - can't tell exactly where its coming from but as it is in the brake hose or bleed valve I assume it is piston. When I changed pads and disks last week piston looked healthy with the rubber graumet etc. Didn't notice rust thst would be getting in there.

It's not spraying but it is close - there is a pretty drizzle chance of brake fluid pressing the pedal.

Thinking about it what tools/parts will I need to crimp a replacement piston clar claw assembly correctly?
 
Sorry but I feel you should give this job to a garage......…………I understand there could be something lost in translation but looking through that will you feel happy driving the car with brake repairs that you're not confident with......especially if you have a family...…..
For what it will cost you, you will have the peace of mind that they will make sure you are safe...….and probably spot any other possible problems with the brakes
Please don't be offended by my comment but some jobs are too safety critical to be carried out by inexperienced owners...…...just ask yourself would you let your neighbour do heart surgery on you just by using other peoples advice off of the internet.....probably not.
 
Kernow A2 said:
Sorry but I feel you should give this job to a garage......…………I understand there could be something lost in translation but looking through that will you feel happy driving the car with brake repairs that you're not confident with......especially if you have a family...…..
For what it will cost you, you will have the peace of mind that they will make sure you are safe...….and probably spot any other possible problems with the brakes
Please don't be offended by my comment but some jobs are too safety critical to be carried out by inexperienced owners...…...just ask yourself would you let your neighbour do heart surgery on you just by using other peoples advice off of the internet.....probably not.
Click to expand...

I understand your concern, but i am fine doing the work - Will have a quick check on the process and check up tools - it does look like i'll need the piston/clamp assembly just need to find if i can undo the hose bit from the metal assembly and screw it back on or not. It is fairly straight forward and if I do get stuck i'll give a call to my mechanic friend - it's a non issue.

Would've tackled it further today but it is pouring down thick and it's not the most pleasant/ideal situation to try and spot a leak.

Oddly enough this seems to be the assembly which had been replaced previously (much less corrosion) and what looks like original piston assembly on other side works flawlessly...

I'll order in a replacement assembly with piston and that should sort the issue

Appreciate the concern @Kernow A2 and completely understand - i'll be fine :) this is far easier than massaging the gearbox out and back in! figure these out alright it's just annoying ending up with bits off and not having a tool for one last bolt etc.
 
Un4tural said:
I understand your concern, but i am fine doing the work - Will have a quick check on the process and check up tools - it does look like i'll need the piston/clamp assembly just need to find if i can undo the hose bit from the metal assembly and screw it back on or not. It is fairly straight forward and if I do get stuck i'll give a call to my mechanic friend - it's a non issue.

Would've tackled it further today but it is pouring down thick and it's not the most pleasant/ideal situation to try and spot a leak.

Oddly enough this seems to be the assembly which had been replaced previously (much less corrosion) and what looks like original piston assembly on other side works flawlessly...

I'll order in a replacement assembly with piston and that should sort the issue

Appreciate the concern @Kernow A2 and completely understand - i'll be fine :) this is far easier than massaging the gearbox out and back in! figure these out alright it's just annoying ending up with bits off and not having a tool for one last bolt etc.
Click to expand...
When fitting the rear brake pads did you use a compatible piston wind back tool or just brute force ?
 
Used a tool to twist and compress. It was leaking slightly previously mind... but couldn't tell where from, so did pads and cleaned it up to see if becomes more obvious - which made leak worse.

Pretty sure easiest to just get a replacement piston/caliper assembly at this point - can't imagine anything else in there leaking as it's not hose or bleed nipple.
 
From the info it does sound like a blown seal in the caliper
Changing it will entail bleeding the system with all four wheels off and an assistant, + best check all bleed nipples for function first
Heat may help there
An opertune time for complete brake flush and fluid change too
 
I'll pinch the hose and swap the caliper - did a bleed/flush when i was doing brakes, should've looked further into it last weekend when i was doing it to be honest but left it as it didn't seem it was leaking anywhere obvious and whole caliper was damp - one of those do right or do twice type of jobbies i guess, just didn't expect the twice part to come back this quick :D

I assume it is just the one bolt holding the hose in on the caliper/piston assembly near bleed valve?

luckily it's all fairly quick/easy so can bang it out in an hour or so after work as long as it isn't raining now that I'm familiar with the assembly.
 
The washers for the banjo conection of the brake flexi to caliper can corrode and leak, copper washers are best suited (presuming its a banjo connection here more a wide ranging vag issue) however i presume yours is a actual caliper fault, had the same thing happen to a passat and was suprised it could leak through the rear of a caliper
 
54.77 from euro car parts seems quite reasonable for a pagid caliper after retuning my one back, seems to be a rebuilt part.

Will go over the belly when weather is more ground and less lake to see if there is any other visible issues anywhere.

@Howey surprised me too - was convinced it was either the pipe of bleed nipple leaking
 
New caliper on will bleed it properly tomorrow as i reckon i have air in the system somewhere it clamps down but applies no pressure to the disk/pads, pedal goes to floor with little resistance and i cant find any suitable tubing around house. Apparently looking for tube suitable to bleed brakes is not why we go to the kitchen for, who knew. ?

Otherwise brakes work fine minus the new caliper corner just brake pedal goes to the floor. No i didn't test drive just back and forth a meter in the space. Nice and shiny now.
 
Carrying on with adventures - cannot bleed that rear left, i have a feeling i got more air trapped in the system and probably master cylinder as it isn't pushing liquid to the bleed valve, not had the chance to check if other corner bleeds... as handbrake works fine on it i assume caliper itself works as presumably the cable clamps it using hydraulic force?

I assume that's what it is, as it did leak out a bunch and reservoir was empty... so will need to bleed the whole thing... again.

b****r, will leave it for weekend as poking in the dark isn't ideal.
 
Un4tural said:
Carrying on with adventures - cannot bleed that rear left, i have a feeling i got more air trapped in the system and probably master cylinder as it isn't pushing liquid to the bleed valve, not had the chance to check if other corner bleeds... as handbrake works fine on it i assume caliper itself works as presumably the cable clamps it using hydraulic force?

I assume that's what it is, as it did leak out a bunch and reservoir was empty... so will need to bleed the whole thing... again.

b****r, will leave it for weekend as poking in the dark isn't ideal.
Click to expand...
Just wondered if you did as the manual instructs - fill caliper with brake fluid and then mount caliper (from memory).

Andy

Edit. If you have VCDS I believe it can be used to efficiently bleed the brakes.
 
Best to keep reservoir topped up as your assistant pumps the pedal

Also do not allow the pedal to travel to the floor a block of wood or similar below will prevent possible damage to the master cylinder seal lips

Or the job just gets bigger
+
A length of clear silicone washer jet tube to bleed ECP should have by the meter?

Certain hand brake operation is mechanical
Not hydraulic
 
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Thanks guys I'll give it a tackle Saturday I reckon with some daylight, been to half the local homebase and b&q and I am guessing everyone doing their brakes as can't find 7/8mm ID tube anywhere, the nice flexi stuff.

@Andrew ill take caliper off and give it a bit of a jiggle just in case it has some stuck somewhere in there as that could be likely thinking about it - fluid does seem to flow alright to the entry point to caliper when I indo it there but bleed nipple seems to be slow to flow barely getting any flow through.

Not sure if free version of vcds lite allows to run the brakes bleed cycle, I know my Bluetooth doodad had the function but lil sucker let the electrons escape.

For now ill hunt down some clear flexi tube I think 7mm I had that fit perfectly last I bled them and crack on with some daylight.
 
Righto - so seems it has quite a few air bubbles - ordered more brake fluid and will go have fun bleeding everything, likely tomorrow.

guessing overnight with the leak reservoir gone empty as it had quite a bit leakage and pulled in air...
 
Good luck. I got an eezibleed kit and it came with clear tube. About £5.

Your handbrake is definitely manual. A Bowden-style cable through the backplate attaches to the brake shoe. It’s all physical in case of catastrophic failure of electrics, pumps, hydraulics, electrics. Emergency brake.


Sent from my iPhone using Tapatalk
 
Well then - bled it some more (twice fresh fluid now! twice better?) and it is fine, pedal feels good (though it goes down more, but it now stays pressurized fine, could be that i just got used to fiat brake that feels like stepping on slab of wood.
Lesson for the future, try to not let it leak out too much fluid so that it gets air in the system. i guess.

All in all really easy job just didn't see having to go through bleeding system was going to be part of the job.

Old caliper was leaking through the back by the way - seemed to be gushing out from around the bolt circled, looks like that bolt should just be holding the hand brake assembly but not going to go taking it apart now plus need to pass it back to ECP for the hostage money/deposit back.
s-l1600.jpg
 
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