Rear brake cylinders - fluid in boots, OK?

[Spathodus77]

Hi all,

My brake woes are continuing and fatigue is settling in. HELP ME I'm trapped in s series hell. A short recap on the last 10 months...

1) Replaced front hoses, callipers and pads
2) Could n't bleed the brakes
3) Found the rear brake cylinders were leaking. Replaced rear brake cylinders.
4) Brakes still not 100%
5) Master cylinder reconditioned with stainless sleeve and new seals. Servo professionally tested and found to be working fine.
6) Could n't bleed the brakes.
7) Small dribble of fluid between M/C and servo.
8) Master cylinder sent back and tested up to 700psi. Seals all fine.
9) Refited M/C only connected front brakes. Bleed M/C and front brakes. Test drove car (private road). Brakes perfect.

Today: tightened up a couple of the rear fittings. Pulled back dust boots on rear brake cylinders...one shows slight evidence of weeping (see pic), my question is am I going to have to change this again after only 6 months or is a tiny amount of leakage expected? If I am going to have to change it now is a good time because the rears are disconnected.

Thanks,

Ralph

[phillpot]

No amount of leakage, no matter how little, is acceptable unfortunately


Is it definitely a leak and not, considering they are nearly new, some kind of assembly fluid/lubricant ?


How about dry it all out, slip drum back on, stomp on the brakes several times with all your might, open back up and see what yer got

Edited by phillpot on Tuesday 9th February 19:17

[brman]

phillpot said:

No amount of leakage, no matter how little, is acceptable unfortunately


Is it definitely a leak and not, considering they are nearly new, some kind of assembly fluid/lubricant ?


How about dry it all out, slip drum back on, stomp on the brakes several times with all your might, open back up and see what yer got

Edited by phillpot on Tuesday 9th February 19:17

^ what he said.......

[glenrobbo]

When you did your brake overhaul, did you bleed enough fluid through each bleed point to ensure all old contaminated brake fluid was drained off? It is highly hygroscopic, and any water in the system can soon cause corrosion in the cylinders and cause seals to leak. Also any bits of grit or dirt can cause similar damage, strict cleanliness must be observed when changing components.

[glenrobbo]

Spathodus77 said:

Hi all,
Refited M/C only connected front brakes. Bleed M/C and front brakes. Test drove car (private road). Brakes perfect.

Tightened up a couple of the rear fittings. Pulled back dust boots on rear brake cylinders...one shows slight evidence of weeping (see pic), my question is am I going to have to change this again after only 6 months or is a tiny amount of leakage expected? If I am going to have to change it now is a good time because the rears are disconnected.

To follow Phillpot's advice, first you will have to connect up and bleed the rear brakes again Ralph.

Don't despair, you'll get there in the end.
I'm wondering if your difficulty bleeding the rears is due to a faulty brake bias valve ( the component mounted at an angle on a bracket on the outside of the driver's footwell?
Have you got somebody to help with the bleeding, or do you use a Gunson Eezibleed?

[Spathodus77]

Thanks for the advice. To answer the questions:
- when I was having probes bleeding the brakes for the second time I peeled back the boots on the wheel cylinders and they were dry - the fluid has appeared in the last month/30 miles.
- I have used quite a bit of brake fluid with all the bleeding - probably about 6L - all old fluid has been dumped.
- Dirt ingress is always possible, I can't rule it out, however I do work in the pharma industry and frequently find that my definition of clean is higher than most pro garages.
- Brake pressure regulator is a possibility. After I've changed the wheel cylinder I'll investigate further.
- I use an Ezi-bled for bleeding but usually get a assistant to push the pedal as well.

Thanks again.

Ralph

[phillpot]

Spathodus77 said:

- I have used quite a bit of brake fluid with all the bleeding - probably about 6L

[Griffinr]

Spathodus77 said:

- Brake pressure regulator is a possibility. After I've changed the wheel cylinder I'll investigate further.
- I use an Ezi-bled for bleeding but usually get a assistant to push the pedal as well.

Ralph

They can be a pig to bleed even with an ezi-bleed, I think its the brake pressure regulator thats the problem. Pack round it with some rag and crack open the top union, that should shift any air.
Rob.

[phillpot]

Griffinr said:

I think its the brake pressure regulator thats the problem. Pack round it with some rag and crack open the top union, that should shift any air.

Lot easier with a bleed nipple...

[Spathodus77]

That looks a good idea. Does the brake pressure regulator use a metric nipple?

[phillpot]

Spathodus77 said:

That looks a good idea.

All my ideas are good, just some are gooder than others (and one or two aren't very good at all)


Yes, it's metric but you'll still need to connect the outlet pipe somehow



..... unless you're thinking put a nipple in to bleed then nipple out and re-connect pipe? Probably easier to do it Rob's way, loosen pipe union and plenty of rag!

[Blue 30]

Not wishing to steal this thread. I'll start on entitled 'Brake bias valve'.

[Barkychoc]

No fluid leaks should be present.

How is the hand brake - are the auto adjusters working and does the lever pull up really high - it has a bearing IIRC on where the shoes sit and how effective (or not) the auto adjustment is. Lots of brake shoe to drum clearance can result in a poor pedal feel and lots of pedal travel. How is it driving at low speed with the handbrake on a bit - as I said don't drive too fast - you will have to pull the handbrake on pretty hard to lock the brakes up though.

[Spathodus77]

An update:
1) changed the dodgey wheel cylinder.
2) whilst doing this I found that the male Union going into the back of the wheel cylinder had a tiny crack in it. Made up a new piece of pipe with new unions.
3) bled the rear pressure regulator by putting a nipple in the top, bleeding and then removing the nipple. Worked well - I recommend this method.
4) reconnected rear brakes and bled through. Braking system now seems normal...

Thanks to all for the advice.

Ralph

[glenrobbo]

Great to see a successful conclusion to the problem, and good to see feedback from the OP.

This forum works well doesn't it. ( Except for the new improved search. And the Classifieds with windows mobile...... )

[Oldred_V8S]

glenrobbo said:

Great to see a successful conclusion to the problem, and good to see feedback from the OP.

This forum works well doesn't it. ( Except for the new improved search. And the Classifieds with windows mobile...... )

I think after your recent activity, it is a good job the classifieds are beyond your reach Glen.

[glenrobbo]

Oldred_V8S said:

I think after your recent activity, it is a good job the classifieds are beyond your reach Glen.

I can still look on fleabay though Paul I just can't get on the Pistonheads Classifieds
As you say, probably just as well! The kid's inheritance would soon be gone