Brake seals leaking

[ricster]

Last year while on the river trip my low brake fluid light came on halfway through the trip. I thought this was strange as my brake pads are only halfway used and i checked the level before we left. After topping up the brake fluid all was well and before leaving to go to Moz I checked the levels again and all was still well ( had to add a small amount, but nothing that raised any alarms ). About 10Km from Kosi Bay the light flickered on again..... ... I stopped at the garage and bought a 500ml bottle of brake fluid, and filled it up. After some bouncing around on the sand in Moz a few days later I checked the level and again it was down, so topped it up again. I drove home and when I got home it was low again but not low enough yet to light up the dash light.

I cannot see any leaks from the master cylinder side in the engine bay, but on the passenger side hub I can see, what I thought was a leaky Birfield joint ( was like that for a while now ), some wetness around the whole area. I assume that the slave cylinder seals have kicked the bucket.

So now I need to replace them. Anyone have any advice where I can get seals or is it agents only. What type of brake fluid should I use ( dot 3 or dot 4 etc....)?

[AndriesS]

If you can strip them you can always take the seals to Winbrake or Norbrake and they can match it. I did it for the dustcovers on the front calipers.
Might be worthwhile to ask them for a price to refurbish the caliper. getting those seals and dustocvers in are pesky

Dot 4 and 5.1 has higher boiling points than Dot 3, I'll go for Dot 4

[ricster]

Cool thanks.

Does the dot 4 and 5 not mess up the rubber if it is supposed to be dot 3. One hears all sorts of stories, so thought I'd ask the question.

[ricster]

The other problem is that it is my daily drive, and stripping and taking it in to get matched up is going to be difficult...

[ricster]

Anyone know the diameter of the pistons on the front brake calipers. The spares shop says he has 2 sizes. One is a 48 odd mm dia. and the other is a 50 or 60 something dia.

[AndriesS]

Dot 5 is silicon and should not be mixed with other dots, but 5.1 is not. Some say dot 5 gives a bit of spongy feel but it is not hydroscopic like 3 and 4 and 5.1 and also does not damage paint. and it comes in colours, thus when you bleed . change the colourand then you keep on bleeding till you see the new colour.

I've not heard of the rubber thing yet but when you do fit the seals use rubber grease or brake fluid, do not use sunlight liquid - that will give you a pretty mean mess.

Option 1:
As a daily driver , I suggest you call both shops, typical price and time to change seals on your calipers ( I think it's a 2 piston sliding caliper).

Option 2:
Ask Mr Volschenk for 2 loaners, fix them , swap yours out.

2 random thoughts:
have you checked:
Just out of interest as I assume you have Diesel and those should have vacuum pumps, does you vacuum pump not have liquid leak. Some petrol engine guys will complain about smoke that turns out to be brake fluid being sucked into the engine as their master cylinder is actually the problem.

Word of caution:
I've had bad experiences doing brakes on high milage cars, when you use the normal bleeding process, (pomp, hou , pomp hou) then you use a part of the master cylinder that has not seen any use in a very long time and then soon afterwards you master cylinder fails and that is why I haven't changed to longer brake lines yet
I think you have three options, put a spacer underneath the pedal to prevent all the travel, use a pressure system to bleed , use a vacuum system to bleed. I use vacuum bleeding and last bit the old manual method.
I would love to hear other opinions on this.

[ricster]

Thanks for this very valuable info.... will give it some thought!!

[ricster]

Ok... so I had to nip out the office for a few minutes and stopped at the spares shop to get another bottle of brake fluid as the light was on again. While pouring in more fluid I noticed fluid leaking out from the rubber shown by the arrow. ( photo nicked off the internet )

booster 1.jpg (54.51 KiB) Viewed 5299 times

So now I'm confused and know VERY little about these parts of my Patrol. I tried to push the reservoir back, thinking that it had popped out, but it wasn't going back in. The leak seemed to stop/slow down though.

I assume that a brake master cylinder kit will have a new rubber seal specifically for that.... or am I smoking my socks?

How easy is it to do the repair, and how long would it take roughly? Any pics on how this thing comes apart etc??

[AndriesS]

If it is that seal it should be fairly easy, pop off the reservoir, pop seal out and put new one in. That is if they are available. It should be part of the master cylinder kit.

You should not need to bleed your brakes either

[ricster]

ahhhhhh.... awesome news. Thanks mate !!!!