Clutch fluid loss

[Chris]

A little help please. I am losing clutch fluid. I've changed the master cylinder for a new one. I cannot find a leak anywhere. It seems to be sporadic and I am wondering if it is something to do with heat i.e. is the slave cylinder getting hot and letting fluid go?

I sat in the car this morning and pumped the pedal like a gym session and no loss at all. Last evening I got stuck in traffic for 25 mins and obviously things got a bit warm. Somehow I lost a bowl of fluid.

I am running a UN1 slave on the top of the bell housing. I do have 'aircraft standard' heat shielding under the bundle of snakes there but maybe not enough. I can't see that clearly but it does not appear to be leaking there when cold. I need to take the exhausts off to have a proper look but before I do has anyone else had any similar experiences??

 

[Chris]

Update - I have taken the sump guard off and there is definitely brake fluid on the bottom of the bell housing. It has to be at the slave or very near. Still could not see anything and still no leak cold even after more pumping! I will obviously have to take the exhausts off but not today. There is some filming being done this afternoon (me and my cars (eek!)) and a local car meet tonight so it will have to wait a day or two!!!

 

[Brian Kissel]

THANKS for the update Chris !!!

Regards Brian

 

[Don]

Hi Chris,

I am having the same problem, like you my Renault Box has the slave cylinder at the top, and this affects the fluid as it gets hot, I am not loosing fluid, but the action of the clutch is diminished after a while My exhaust builder said to talk to Imico who can do a Thermal shield, this should stop the heat getting through. I have emailed them yesterday, so hope to be speaking to somebody soon.

 

[Mark Boyers]

just a heads up boys there are really good quality cylinders and there are some really cheap nasty cylinders and it does make a difference.

 

[Frank Catt]

Take the slave off the car, pressure test it as is, then machine a sleeve that reduces the bore to either 25mm ( or 22 mm which I use ) and fit a new piston. Pressure test again before refitting. Use -4 Pipeline , not the original -3 . Test on car then fit ali heat shield .

 

[Jean-Marc]

Other solution, put a slave in line with the gearbox entry shaft (coaxial), there are plenty of models, they reliable an almost insensitive to heat because enbended in the bell housing.
I have this on my 427 Galaxie for years.

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[Chris]

Other solution, put a slave in line with the gearbox entry shaft (coaxial), there are plenty of models, they reliable an almost insensitive to heat because enbended in the bell housing.
I have this on my 427 Galaxie for years.

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Yes, I run one in my 427 Cobra but I am not convinced there is enough room for one in the Renault gearbox - if anyone knows different I would be very interested.

 

[Chris]

Another Update!!

So I took the car out last night to a local meet. No getting hotter than average as there were no queues! Not a drip of fluid disappeared. So it's definitely a heat issue.

I took the exhausts off this morning to have a closer look. I'm now hoping that actually the problem is heat warming the remote bleeder outlet, as that was the only place I could see a trace of fluid. I have made up a new piece of pipe (the flare had a slight blemish on it which wasn't helping) and replaced that.

I am now in the process of improving the insulation and will then try it again before I go to the trouble of sleeving down or anything else. This is on the basis that whatever, if I can keep it cool enough, it doesn't leak and works fine!

Onwards!

 

[Chris]

And another update!

I took everything off and improved the insulation across the whole area using foiled backed material (it's not asbestos but it looks like it!), making some little supports up to keep it tidy. I kept my 'aircraft quality' expensive stuff as well. Went on a 80 mile run yesterday (probably the hottest of the year here) and spent time in traffic and at lights etc. Just a tiny bit of fluid lost, and to be honest, there might have been a weep at the master cylinder as there was a little fluid there. I have now tightened that union but I think I have cured the problem. I might add some high temp fluid just as a precaution (probably should have used that in the first place).

Nearly 3000 miles now since mid January. Loving the car, great fun to drive