Leaking wheel cylinder

[gergstuff]

I noticed wetness on the inner right rear tire the other day and pulled the wheel and drum to find the wheel cylinder oozing brake fluid. The little rubber boots were not on all the way so I pushed them back on. I would have thought those were to keep dust out and not necessarily keep fluid in. Is that right.

The wheel cylinder is not that old, I think Chuck replaced it for the previous owner only a year and a half ago or so. The car ('67 MkII) sits more than it is driven now.

I have been using DOT 3 brake fluid, could that have caused the early failure?

I imagine they are not too expensive so I should just replace it, I am more curious as to why it would fail so soon.

As always input is appreciated.

Thanks,

Craig

[Mark]

Hi, Sorry to hear about the leak.
The first thing is, never use plain old dot 3 Brake Fluid if your car sits. On all cars, driven or not, you should prob use DOT 4. Castrol makes a dot 4 that has Low Moisture Absorbtion on the bottle that will ever so slightly decrease the amount of moisture that the bf is trying to suck straight out of the air. Most of the time, if Castrol isn't available, go to NAPA and get their DOT 4. It's supposed to be better.
But, if you know your car will sit alot, consider the very thorough cleaning of your system using great care to install all new seals, then go with silicone bf. Most, if not all silicone bf's also offer a much higher boiling point, which will benefit by not allowing the bubbles (caused by heat / boiling regular bf) to quicken the moisture absorbtion process.

Second, most of the recent wheel cyls in the marketplace only last 1 - 1.5 years. This information directly from a renowned california Mini expert. If at all possible, try to get the lockheed stuff. ( For two reasons; the lockheed stuff can sometimes be okay with a replacement "rubber kit", and the "other" parts guys whl cyls can't use lockheed kits most times, and they don't offer kits that fit their "other" wheel cylinders. ( From what he said, the others are chinese, aren't marked at all, and are obviously lesser quality. )

All of that said, I have a chinese wheel cyl or two that you are welcome to (free) if you want. I'm not certain if what I have is suitable for your mk 2 or not, but we can figure it out. ( is your car an s, or does it have front discs ) I would only think of these as temporary fixes until you can get the lockheed one installed. Possibly, just possibly, you could also get a spare cyl or a kit out of the tools and parts library by contacting Kelley M on this board; his user id is mascher or mascherk or something like that.

Whew! let me know what you think. Best regards,
MSH

[gergstuff]

Thanks Mark,

I will see if I can source a Lockheed cylinder. The one in the car now doesn't seem to have any identifiable marking.

If they only last a year or so, so be it I guess I can live with that, at least I know it isn't just me.

Thanks for the help.

Craig

[gergstuff]

Oh, I forgot, I just have a plain old mini, drums all around. Seems to stop fairly well, I generally keep off the freeway and stick to the backroads.

Craig

[gergstuff]

There seems to be two different sizes available for rear wheel cylinders 5/8" and 3/4" can they be used interchangably or must I jack up, crawl under and measure?

Thanks,

Craig

[Cheleker]

It would be interesting to know how long ago the cylinder was changed.

Yes, the outer rubber bits are just to keep dust out, not to keep fluid in.

Fluid I would have used would have been Castrol GTLMA Dot 4

Measure the wheel cylinder. Don't mix and match.

If one side is bad, check the other.

[skip]

To add to Chuck's comment. If one side is bad, the other can't be far behind. Replace them both at the same time, you are back there and tooled up anyway.

[gergstuff]

curiously I went under there last night to measure and I no longer see any evidence of leaking!? The right rear tire shows the stains from the prior leak, I had taken the wheel and drum off and cleaned everything up and pushed the boots back on the cylinder. Hmmmm, once again, curious. I will have to keep an eye on it.

Craig

[Mark]

Hi, Please don't trust that it's not leaking any more. It still is, at least in some way, compromised. I'd follow the advise to do both at the same time.
Best of luck, and,
Best regards,
MSH

[gergstuff]

Chuck,

Would you have noted the size of the wheel cylinder on your repair invoice? I still have that. You did all the work for the prior owner about a year and a half ago. Bob Porter was his name I think.

Craig

[gergstuff]

Okay I got it, GWC1101 looks like 5/8". Good job with the tidy invoices Chuck!

Craig

[Cheleker]

Glad Bob passed them on.