Rear Braking system leak

[krazypaul]

This is baffling me a bit so am wondering if anyone else has had this problem.

Just got car back from it's MoT, it failed due to a leaking rear brake system which has now been replaced, calipers, cylinder and springs.

The thing is the rear brakes have now been replaced three times in the last 4 years so clearly something is amiss. Question is, what could be the underlying cause for this recurrent failure?

Car has done 122k and I usually rack up around 5000 miles in a year so not excessive. It's a 320i, 1987 btw..

confused kp

[Gortour]

Are the rear brakes definately knackered each time? Not just some t@sser trying to make money out of you is it?
Did you send the missus in with the car for the MOT? I always take mine for MOT at a place that deals in commercial breakdowns, and do MOTs as a sideline. They just give me a list of faults, and tell me to get it sorted and take it back. No crap from them, cos they're not after the work.

[krazypaul]

The thought did cross my mind but the MoT report states the same fault each time, leaking of brake fluid onto the shoes on the nearside rear. Maybe it's just cheap parts??

I'm stumped.

kp

[Treeman612]

where is the leak from ? - if it's from a rigid-flexi connection, the tapered sealing point on the connector could be damaged, i.e. won't seat properly, so leaks under braking pressure. If it's caliper seals, and you've replaced the whole system 3 times, then take the calipers back and demand your money back! (sale of goods act, product not fit for purpose, etc etc.)

[krazypaul]

where is the leak from ? - if it's from a rigid-flexi connection, the tapered sealing point on the connector could be damaged, i.e. won't seat properly, so leaks under braking pressure. If it's caliper seals, and you've replaced the whole system 3 times, then take the calipers back and demand your money back! (sale of goods act, product not fit for purpose, etc etc.)

I think it might be the latter but I'll check it out.

Thanks

kp

[old_skool]

If it's an '87 320, then there's shoes and drums, not calipers on the back. I would "assume" that cheap pattern rear wheel cylinders have been fitted. Has it always been done at the same garage? If so, talk to them. If not then the likelyhood is that there may be an underlying problem as they can't have all used cheap/defective/secondhand parts.

When you say the brakes have been replaced three times before - did that include the wheel cylinders every time?

[SGP]

A pair of new brake cylinders are not expensive and are quick to fit,I wonder if they were changing the seals instead of the whole cylinder.

[316eyes]

A pair of new brake cylinders are not expensive and are quick to fit,I wonder if they were changing the seals instead of the whole cylinder.

Not likely, it's quicker to fit a new cylinder than do a refurb.

[Brianmoooore]

Distinct smell of fish here!

[krazypaul]

If it's an '87 320, then there's shoes and drums, not calipers on the back. I would "assume" that cheap pattern rear wheel cylinders have been fitted. Has it always been done at the same garage? If so, talk to them. If not then the likelyhood is that there may be an underlying problem as they can't have all used cheap/defective/secondhand parts.

When you say the brakes have been replaced three times before - did that include the wheel cylinders every time?

Yup, them's the puppies.

1st time it was replaced was at a garage that ripped me off soooo badly. Found a Merc/BMW/VW specialist around the corner from me who had to replace it again just 6 months later. He showed me the seals that had perished.

That was 18 months ago and now it's been changed again, on the same side as it happened before which makes me think something ain't quite right.

kp

[Treeman612]

Just a thought - have the drums or shoes been replaced? - the only possible thing I can think of is if the drum is hopelessly worn, with very worn brake shoes, and the automatic brake adjusters are siezed up (common problem). In this (extreme) situation, the slave cylinder may have to push it's pistons out so far to make shoe to drum contact that the seals are failing. If you've paid for three sets of replacement bits, and no-one has noticed worn-out drums/shoes, then that really IS criminal!

[Gortour]

Just a thought - have the drums or shoes been replaced?

Great thinking Treeman. Bet that's it. The drums are worn, the shoes are being pushed out too far and the cylinders are leaking as a result.

KrazyPaul, can you check the rear drums for wear, and is there movement in the adjusters?

Only other thought I have, could the front / rear adjuster be siezed putting too much braking to the back and wearing the rear brakes prematurely?

[Gortour]

Na, scrap the front/rear bit, it's always on the same side. Must be the drum on that side.