That sinking feeling after fitting new master cylinder!

[AndyPen]

Last week my son and I bled the brakes and got a great pedal - all down to the brand new brake master cylinder we imagined. You all know what a pig of a job that is, but had primed it and checked it before fitting and all the usual malarkey.

Yesterday I went back to garage to find the fluid level had dropped - I've one of those extension tubes on it so could see that it was clearly down about 1/4 inch from the top up done the previous week.

I checked each wheel and everything was dry as a bone... then checked the joints and dry too - then I went to the drivers side pedal area and yes, you guessed it - damp with the new fluid.

So it looks as if it is all coming out again and I'll be asking Mini Spares for a replacement master cylinder!

Unless anyone on here has any suggestions perhaps? I've topped it up this morning and the pedal is still feeling good????

[GraemeC]

Sometimes those extensions can be a b@st@rdto get to seal, but that would result in a pool on top of the cylinder rather than a wet pedal.

[Peter Laidler]

Been there Andy....... I hope that you had silicon fluid in the M/cylinder of if not, you caught it before the fluid ruined the paint under the carpet and inside the bulkhead crossmember. What a bugger.... The answer with new repop cylinders must be to pressure test the cylinder part on the bench. Just don't ask me how though!

[AndyPen]

Sometimes those extensions can be a b@st@rdto get to seal, but that would result in a pool on top of the cylinder rather than a wet pedal.

I was hoping it was that, but I used the jubilee clip trick to get it tight on to the seal.

Ho hum ;-(

[AndyPen]

Been there Andy....... I hope that you had silicon fluid in the M/cylinder of if not, you caught it before the fluid ruined the paint under the carpet and inside the bulkhead crossmember. What a bugger.... The answer with new repop cylinders must be to pressure test the cylinder part on the bench. Just don't ask me how though!

It is new dot 4 stuff Peter, but this particular car has had a leak or two in the past so it is a bit botched down there already. The only bit of original carpet left though

[mini_surfari]

Obviously you've probably checked it, but the extensions on my leaked fluid on to the top of the master cylinder, and then ran down the back of the cylinder to the base plate. As Graeme said, they're a B*gger.

[AndyPen]

Obviously you've probably checked it, but the extensions on my leaked fluid on to the top of the master cylinder, and then ran down the back of the cylinder to the base plate. As Graeme said, they're a B*gger.

I've put some tissue there just in case that is the problem - my fingers are very crossed but the top seemed totally dry when I looked and the lip usually holds some of it at least.

I'll be over there later to check....

[mk1]

Bugger!

Certainly sounds like a dodgy Mastercylinder.

[AndyPen]

Base plate dry and fluid level dropped below the can top, so got the heater pipes off for a nose under the dash... and yep, the special little home for those lovely little clevis pins was pretty damp with a tell tale drip on the forked rod.

Kettle borrowed from kitchen (with wife approval), lots of warm soapy water sprayed in there (great those weed killer sprayers) once the carpets were out and luckily perhaps, with very little dripping down into the floor well, it could have been a lot worse!

Mopped it all up with a kitchen roll or two. Modified a plastic milk bottle to shove up there to deflect new drips onto some plastic. So while you guys are enjoying 'Boolie' I'll be fitting the new can that hopefully arrives tomorrow.

Love the mini

[Spider]

Bummer for ya. Isn't this why we buy new stuff so things like this don't happen?

The answer with new repop cylinders must be to pressure test the cylinder part on the bench. Just don't ask me how though!

Actually, I think Andy would likely find under pressure it will seal but under no pressure that it leaks. You know what I'm getting at here Pete, the shape of the seals,,,

So probably, the thing to do would be to fit a bleed nipple to it then fill and stand it for a few days before fitting.

This is also why vacuum bleeding these system isn't a good idea as the design of the seal is to work with pressure not a negative pressure.

[Peter Laidler]

Yep, very valid point there Chris that I hadn't thought about. The shape of the 'pusher' seal. Like you say, you could fill it and let it stand for a couple of days but......

[Spider]

but......

Quite !

[AndyPen]

I did wonder but this morning when I got there the tell tale drips were very much in evidence.

When I pressed the pedal there was a slurping sound and a rapid series of drips. Here's what I found on arrival this morning when I started to pull the split pin out.

[AndyPen]

I couldn't leave it like that so later in the day managed to get back and pull the 'can' out.

Sure enough the lower seal was full of fluid as expected... so hope the next new one doesn't have the same issues!

As the car has cooper discs these days, decided I'd upgrade to an S one too. At least that makes me feel a little like I am getting somewhere!

[Peter Laidler]

Pretty conclusive I'd say Andy! Is it a defective CAN or defective SEAL. Maybe they'd send you a seal set free to try first......... at least you can test it out of the car befoire fitting! Maybe your experience is good advice for anyone to test a new can before fitting it

[AndyPen]

I've not got around to dismantling it yet Peter but almost certainly a seal failure. Everything was dry except for the lower rubber cup and anything below it.

Minispares new S one has arrived now, so just going ahead with fitting that one and crossing my fingers. I will of course put a little fluid in and test first, but then again I did that with the other new one too.

[mk1]

I would STRONGLY suggest that it is NOT a good idea to dismantle it yourself as if you do your warranty goes up in smoke.

Just send it back & get a credit or a replacement. It's brand new & not fit for purpose, if it was an old part that had been used & abused, then all well and good, investigate & repair. It's not your job in this case.

[Costafortune]

As above.

Plus, I wouldn't get another from this source. You don't know who is reconditioning them.

I would get an old one sent to a specialist who would bore it out, fit a stainless sleeve and new seals before pressure testing it. I've had this done before. Tbh, unless it comes in a BL box, I wouldn't touch any of this stuff.

http://www.pastparts.co.uk

[AndyPen]

I would STRONGLY suggest that it is NOT a good idea to dismantle it yourself as if you do your warranty goes up in smoke.

Just send it back & get a credit or a replacement. It's brand new & not fit for purpose, if it was an old part that had been used & abused, then all well and good, investigate & repair. It's not your job in this case.

I bought it last year it seems and most unlike me, have not found the receipt as yet. I keep everything so it will be there somewhere.

I am fairly sure it was from mini spares as I have been using them for most things, but wouldn't wish to assume this until I find the darned receipt.

I subsequently got NOS Lockheed originals at the NEC, so they are in storage and ready to be re sealed if needs be and used, but the 1071 would benefit from those. That project has stopped in its tracks as I get this 970 back together in our SDL.

One sep forward and all that!!

[mk1]

One step forward and all that!!

I know that feeling VERY well indeed!