Brake Fluid Level Dropping

[taffy1967]

Over the past few months I've found I've had to top up my brake fluid reservoir a bit. My Mini hasn't been used lately though (I'm doing a few bodywork jobs on it and I've got replacement front seats waiting to go in once I've given them a good clean) and it's always garaged. But today I popped the bonnet open to check the fluid levels and the brake fluid reservoir had dropped down to just beneath the minimum level.

What's odd is the little black rubber cap that covers the test button on top of the brake fluid cap had fluid on top of it. I wiped it with a tissue and it wasn't water, no I'm pretty sure it was brake fluid and this isn't the first I've noticed that cap to have some residue on it.

There's no sign of any brake fluid leakage underneath the car and the rear brake cylinders (on both drums) were replaced last year for the MOT with top quality Unipart items from Mini Spares (I chose the most expensive 'O/E type' they had) and the shoes were also replaced at the same time.

I had that work done by a local garage, because apart from adjusting the rear brakes and topping up the brake fluid I prefer to leave the brakes to the professionals (who I hope are just that).

So could this be a problem with the rear brake cylinders again, or could the fact the brake fluid appears to be under some kind of pressure to be appearing on the brake fluid reservoir cap have something to do with the brake servo?

I've got the tandem type brake servo as fitted to all post October 1988 Minis and I've heard that when the servo seal goes it can fill up with brake fluid.

So could that be the problem here?

Oh and my Mini is a 1990 Mini Cooper (Mainstream Carb model) and the braking system is totally standard with 8.4" discs up front and standard twin pot callipers.

Any help greatly appreciated and I'd also be interested if anyone can recommend me a good Mini friendly garage within a 20 mile (hopefully less) radius of the Rhondda Valley, as I'd prefer to take it elsewhere for a change.

[jb]

taffy ,not familiar with your set up but does the servo have a slave cylinder fitted to it? if so it`s worth checking the seals in the slave cylinder for leakage into the servo. or if the master cylinder is bolted directly on to a servo check these seals as well.

[taffy1967]

Thanks for the reply and this is the set-up my Mini has: -

Before a little clean up and removal of the rotting bulkhead sound deadening material: -


And after: -


There is a slave clutch cylinder, but I'm not too sure about the servo?

[jb]

taffy, to check master cyl seals you will need to remove master cyl from servo by undoing the two half inch nuts , do not undo brake pipe unions then carefully pull master cyl forward off servo if seals are leaking you should find evidence of this in the recess at front of servo where master cyl fits. hope this helps

[taffy1967]

Cheers jb, so I assume those are the two nuts on the front of the Servo at the quarter past and quarter too positions (if it was a clock face like)?

Thanks and I'll have a go on the weekend if I get a chance.

[jb]

yep , thems the ones! i`m off this weekend if you need help/advice whatever