Brake fluid leak - rear caliper with epb

[shagi101]

Hi Guys,

Troubles again.

turned car on after a thermostat change and coolant flush, brake warning... checked fluid in brake reservoir and it was totally empty (car hasn't moved for a few days).

Filled the reservoir up 3 times fully and all times the fluid just disappeared down the hole, 4th time it stabilised and wasn't going down.

Found a puddle of brake fluid at drivers side rear wheel, took wheel off and saw fluid remains were in a lot of places but concentrated at the bottom of the parking brake motor (trickle down from somewhere?).

tried to recreate the leak for a long time but couldn't see any more drips (cleaned it all up and tried some more brake application, epb application still nothing). puzzled!! fluid level was not dropping.

further investigation...parking brake motor off, saw a little bit of fluid (and lots of crap) on the interface between motor and caliper but nothing obviously screwed up. Took the caliper off, dismantlement it and cannot see any damaged seals or anything that could potentially leak that much fluid. Slight play in the parking brake screw thing (inside the caliper)...which is only protected by a small washer inside... I guess this could leak a little bit.

Am I missing something?

[RichardSEL]

If it's at the caliper and the brake fluid leak isn't running down from somewhere else into the caliper then change the caliper complete with EPB -- seems you've got a seal that's leeching under pressure but otherwise not when there's no brake pressure.
Safety critical item -- £140-odd for a new one with returns rebate on your old -- for your and others' safety

You can see what caliper you have from this site by entering your VRM:
https://www.partsinmotion.co.uk/car-parts/brake-friction/calipers/manufacturer/trw

Pre-bleed the new caliper before you fit

[martin1810]

With the epb you are more likely to get a leak without pressure than with pressure because of the design. So a standing car with a poor caliper to motor seal will leak but not when the system is under pressure. Never question brakes. Just fit new parts. Life is short enough, you don't want to make it shorter.

[shagi101]

An update for anyone interested here...

I managed to get a new genuine EPB motor for £70 (probably wouldn't have needed to replace this but I broke the old one) and a full rear caliper rebuild kit for £10. Replaced all the seals (the caliper to motor seal was noticeably worn on my old unit which looks to be the culprit letting brake fluid through to the EPB motor, all other seals were in excellent shape and the piston was almost brand new).

So I rebuilt the caliper a week ago and everything has been working as it should.

This is a safety critical system and the advice to fit new parts stands but, if you know what to look out for and what to do, you can save a couple of hundred quid and perform a rebuild...its what ultimately happens to your old unit when you send it back.