Master cylinder/Reservoir leak?

[edd_barker]

Hi all,

Driving down to Bath on Friday I noticed I was getting more and more travel from the brake pedal, and less and less stopping power....uh oh.

No time to check until Sunday when luckily Kwik-Fit was open and they got it up on a ramp for me. No leaks at wheels but brake fluid clearly squirting out of the bottom plate to what I assume is the fluid reservoir, with the actual cylinder inside?

Mechanic removed the flat plate, cleaned it up and sealed it with some gasket compound, and it got me home with no further fluid loss, but spongy brakes from I assume air getting in after the reservoir had gone completely dry.

Do I just replace the gasket that I assume goes under the flat plate (held on with four bolts) or new master cylinder? Is that chamber beneath the plate under braking pressure? Fluid seemed to have squirted out pretty far.

Won't mess around with resealing I'll just get it done.

Thanks in advance!

Edd

[Trickydicky]

Hi,

The M/C sits in the chassis leg and most likley the seals have failed. the cover plate is just that, a cover plate. Personally I would just replace the M/C. The cost of a new M/C is around £65. You can get new seals but as you have to remove the M/C to replace them you may as well just fit a new M/C.

In the technical tips section there is a guide to replacing the M/C.

[bmcecosse]

Your description doesn't sound like a normal Minor master cylinder!! There is no 'flat plate' to see when the car is up on a ramp...... If it is - then Quak Fut have ripped you off...and left you with a very unsafe motor car. Don't drive it again until you have a new master cylinder in there.

[JOWETTJAVELIN]

He may be referring to the toe-board covering the gearbox and m/cyl.

[bmcecosse]

Yes - but you don't see that from below 'on a ramp' - and sealing it ?????

[edd_barker]

Thanks for replies all...

There was definitely a small flat plate that we removed using the 4 bolts, about 5cm by 3cm. It was obvious that fluid was being forced out the join and that a gasket had failed.

I will get a picture when I can get underneath it Wednesday.

This was tucked right next to the prop shaft...it's possible it wasn't the cylinder and I'm looking at something else?
Hard to confirm it was brake fluid as had run over the oily underside.

100% visable from under the car, next to P shaft. No experience with brakes so I could well be wrong!

Thanks again

[kennatt]

We wait,with bated breath

[taupe]

Hi

Sounds to me like you have resealed the rear suspension damper!

The master cylinder is normally just in front of the drivers seat within the floor unless you have a modified braking system.... Can I suggest that you get a manual or at least an owners handbook.

Taupe

[edd_barker]

I have a manual and have used it to remove and refill the rear dampers successfully, definitely no flat plate to remove there, and also definitely not tucked next to prop shaft.

I will get a picture posted ASAP. Are master cylinders ever moved from chassis leg? Am sure I could see up to where you refill brake fluid, in drivers footwell.

[taupe]

Hi

The master cylinder needs to be close to the brake pedal which operates it.. usually via a pivot and rod linkage.

It is possible to have a remote reservoir on some conversion systems.

A picture would help the forum to sort this out for you.

Have you looked in the chassis leg yet?

Taupe

[kennatt]

Are master cylinders ever moved from chassis leg?......................................not unless there has been major alteration to the brake system,like ,are the pedals still sticking UP through the floor,or hanging down from under the dash.And there should be nothing,that I know of,tucked up anywhere near the propshaft that would be connected with the brakes. Very strange.

[IslipMinor]

Am intrigued about this one - the picture could be quite interesting??

[edd_barker]

MYSTERY SOLVED!

Got under the car today, as well as removing all the carpets and thinking more logically...

The plate I was referring to sits directly beneath the gearstick; its round with 4 bolts holding it on. This had been leaking copious oil. I did question the Kwik-Fit mechanic as to whether it was brake fluid but he was pretty adamant. In my defence, I've never worked on brakes before and had just run a half-marathon in a gorilla suit.

Upon removing the plate from the driver's footwell that covers the master cylinder, I could clearly see the chassis leg full of brake fluid (I know what it looks like now). So I will replace the master cylinder using the forum guide, bolts have already been reversed so hopefully not too hard.

Anyone know the name of that plate and I can get a gasket? or may just Hylomar as assuming its under no pressure.

Also can anyone recommend a brake-bleed kit for a first timer? Very steep learning curve for me in my year of Morris ownership so far.

Thanks again to everyone for their thoughts and interest. Much appreciated!

Edd

[IslipMinor]

Mmm - just need to be very careful with Quack-Fit - they may know a little about tyres, but obviously struggle to tell the difference between brake fluid and engine oil. Since they wrecked a brand new wheel on my wife's Golf GTi many years ago, I have never used them again, and this has confirmed that I never will.

The gearbox gasket BMC part number is 2A3341 for both 948 and 1098 gearboxes - Charles Ware MM shows it as 10G225 @ £0.65 + VAT.

More urgently is to clean all the brake fluid out of the chassis leg - it will strip the paint and absorbs water, which then corrodes the leg from the inside out. Easier done with the master cylinder out of the way.

[edd_barker]

Thanks for the part no. I couldn't find it on bull motif so I'll call CW tomorrow and get one.

Much appreciated!

[bmcecosse]

Good grief....Kwak Fut took the little base plate off the remote control - and told you they had fixed your brakes ????? Let this be a warning to all............... Did they have the gall to charge you money for this 'brake' repair?? You then drove home happily thinking your brakes had been fixed......when frankly by far the safest move would have been to have it recovered by your breakdown cover. For the safety of others - I would be straight down to Trading Standards !!

[edd_barker]

Yes did 120 miles back down the motorway...bit scary now I've realised.

I did have doubts that a flat plate and gasket would seal against braking forces but was so tired at the time I was just happy when they said it'd get me home. Lucky escape, glad to have lived and learnt.

[Trickydicky]

You cant get thicker than a Kwikfit fitter

[simmitc]

As to bleeding kits, the best one really is an assistant to press the pedal whilst you operate the bleed screws. There are kits that force the fluid through by air pressure from a tyre, and others that suck by using a venturi from a compressor. They certainly work on some cars, and I have used them on Minors, but the best is still the tried and tested assistant. You will need a glass jar and some rubber tube as well; all covered in the manual, but any questions, just ask.

If you're in the mood, it would be a good idea to check and renew the flexible hoses and the seals on all cylinders; and flush the system with clean fluid - I prefer silicone as it does not corrode paintwork or absorb water (that could start another debate).

[bmcecosse]

All you need for bleeding is a spanner to suit the nipples... a length of flexible plastic tube that will fit over the nipple - and a small jam jar with some fluid in the base. Fit the tube - open the nipple a quarter turn - press the pedal down hard, hold it for a second or two then gently release ... Then sit back, enjoy a cup of tea/coffee - and watch the little bubbles of air run down the tube. When they stop - close the nipple - top up the reservoir, and repeat all round the wheels. Simples!