Contaminated clutch fluid

[markyp]

I removed my master cylinder today due to a leak around the nose seals and found the fluid to be very contaminated.....The master cylinder was only replaced about 14 months ago and i have done 15,000 miles.

I have also replaced the clutch and slave cylinder 13 months ago, So am unsure of the point of contamination.
So it looks like a new master cylinder and bleed the system through with fresh fluid.....And possibly add a remote fluid tank.

[Synchromesh]

When my slave was leaking badly my local MGR specialist said master and slave should always be changed together but they didn't know why. I rang the LUK technical department to see if this was true. They agreed and said the seals in masters and slaves are susceptible to contamination from dirt and other fluids. Because the master reservoir is inaccessible people decant brake fluid into smaller containers that are dirty or have previously contained oil or other inappropriate fluid. They said cross contamination can occur from an old master to a new slave (and vice versa). In my case the bulk of the cost was the labour for changing the slave and changing the master did not add significant cost so I decided to follow the advice of the MGR specialist/LUK and change the master so my old master would not contaminate the new slave.

[T-Cut]

The usual contaminant in the clutch fluid is black rubber dust from the master piston seal. Your photos show something completely different. Almost like a separate, incompatible fluid has been added. Looks almost like a foam/scum floating to the top. It's definitely not from the clutch fluid. Strange bluish colour.

TC

[Synchromesh]

LUK technical department said a standard brake fluid bottle is too big to top up 75/ZT clutch master cylinders so people find a small container lying around their workshop and don't clean it out properly. Sometimes the container contains dirt or it has been used for other vehicle fluids such as oil or antifreeze. I wonder if mixing oil or antifreeze with brake fluid reacts to produce the greasy looking substance in the photographs.

[markyp]

I have stripped the master cylinder down and drained the remaining fluid from the pipe. This fluid is a slightly cloudy yellow, and not the milky blue colour of the contaminated fluid in the master cylinder.
The leaking nose seal has the numbers D22403 and is a double lip seal...
the cylinder bore is smooth and undamaged.
So if i can find a replacement seal i will rebuild the master cylinder and fully flush the system.
Hopefully none of the sludge from the master has found it's way into the slave.
The master and slave were new and sealed when i fitted them..., but i did fit the master 1 month before replacing the clutch and slave....So it is possible that the previous owner has put the wrong fluid in.

So the hunt is on tonight for a seal that will do the job..:twonk:

[markyp]

I have cleaned the master cylinder,pipe and rebuilt using the original seals as i can't see anything worn or damaged.
It could have been the contaminated fluid or the sludge that was causing the nose seal to pass..(hoping).
Bleed the cylinder and pipework throughly with fresh brake fluid....:).
I will refit the master cylinder and bleed the slave through in the next couple of days, and see how long it lasts.

[T-Cut]

So the hunt is on tonight for a seal that will do the job..

Many have tried. None has succeeded. Best of luck, it would be a Godsend.

TC

[jonno12]

any update:)

[jonno12]

any update:)oops!sorry a bit premature:getmecoat:

[markyp]

Sorry i could not find a replacement seal....But i have got the dimensions and have refitted the master cylinder.
I bleed the the slave with the master before fitting and pushed 250ml of fluid through before it ran clear.
The clutch pedal is working well and no leaks at the moment...:)
The master is very easy to strip and rebuild, If only we can source an improved nose seal the unit should be more reliable.

The hunt continues......:):)

[markyp]

A final update.....The master cylinder lasted a week and started leaking from the nose seal again,but the fluid in the sysem was still clear.

So instead of buying another new master cylinder i hunted around my local scrap yard and found and new looking slave cylinder in a Rover 75 V6 for £8.
I connected the new(ish) master to the coupling below the battery and bleed a litre of new brake fluid through the slave,then fitted the master into the car.
I have driven 2500 miles since and no leak from the seals...:).and clear fluid.:)
I found it easy to bleed the system before fitting the master cylinder in to the car........However me and the ZT will be parting ways soon..:sad3:...As i would like to buy a 75 connie :driving: