Mysterious clutch leak........

[OZ-Racing]

A couple of weeks ago it took me about 50 minutes to travel 50 meters due to heavy traffic. There was a lot of clutch usage in this time and obviously the temperatures within the engine bay were quite high.
By the time we got rolling the clutch pedal was struggling to return to its normal position without me assisting it by pulling it back up. When dipped the clutch was barely disengaging :x
It got to the point where I had to pull over, call the breakdown company, get an earful from the missus for "having such an old, unreliable, jap-crap piece of shit that's always breaking down" :shock: I'll have you know that this was only the second time I had called the breakdown company in over 3 years of ownership, and the first time was a couple of months ago for what turned out to be a fooked thermostat. :roll:
I'm getting side-tracked......... so while waiting for recovery, I inspected the master cylinder from within the cabin, no leaks. Looked at the slave cylinder, no leaks and the hoses looked fine :?
By the time I got a call to say they would be with me in 30 mins, things had cooled down and there was feeling back in the clutch pedal. I told them not to bother coming and managed to drive home. By the time I got home everything seemed normal again.

I use the car daily and over the last couple of weeks it has slowly been getting worse. So I bled the system to make sure there was no air in there. The fluid that came out was very dark and it looked like there were bits of seal in there.:sad:

I now find that if I drive the car until it's up to good running temperature the clutch pedal rapidly loses feel and I can barely disengage the clutch, so only short trips for me :x

Where do you think the problem is?
- There are no leaks in the drivers footwell
- There is no oil left on the drive
- The hoses are not split or bulging
- There is no oil leaking from the slave cylinder
- It looked like there were bits of seal in the dark oil that I bled out

I'm thinking it may be an internal seal gone on the slave cylinder in which the leak gets worse as it gets warmer.
My reason for this conclusion is that the problem gets worse as things warm up and the slave cylinder will see a lot more heat from the engine than the master cylinder. Well this is what I'm hoping because I don't fancy changing the master cylinder

All helpful input welcome (so no posts from paz please :lol: ), I need to work this one out quickly as it's a daily driver and as there are no visible leaks, I have no obvious clues :sad:

Thanks in advance, James :-D

 

[Matt Evans]

Hi mate, when I bought my R about 4 years ago, I had a string of clutch problems. The hoses split, the slave cylinder went, then the master, then the clutch lever snapped!

From what you've explained, it does sound like one of the internal piston seal has given out, and hopefully it is the slave cylinder one. If you found bits of seal in the reservoir then the seal has broken down and, as you said, when the slave cylinder gets heated up by the engine, the fluid in it thins and pushes past the piston seal instead of getting compressed by it.

Just try changing the slave cyl, it ain't a hard job at all. Plus, what clutch fluid are you using, does it have a high boiling point? Maybe that might help until you change the cylinder.

 

[Matt Evans]

Oh... I just thought of something!

If there's bits of seal in the reservoir, then its probably the master cylinder seal, as the slave cylinder is after the reservoir, and I can't see bits of slave cylinder seal getting sucked back up to the reservoir, but this is just my opinion. I could definitely be wrong.

 

[OZ-Racing]

No, the bits of seal weren't in the reservoir, I saw them in the fluid which I collected when bleeding the system out of the bleed nipple on the slave cylinder. The oil in the reservoir is nice and clean :-D .
I'm using Dot 3 brake fluid.

 

[Matt Evans]

Ok mate, try using DOT 5.1, see if it helps.

 

[Cambridge_pulsar]

Can I put some helpful input? Actually I don't have any just makes a change to see you having problems instead of the rest of us (only joking) Hope you're not using dot 3 brake fluid for your brakes too :shock:

 

[GTi-R23]

Doesn't have to leak to be the master cylinder seals. My master cylinder seal went (clutch pedal straight to the floor) fluid in the reservoir was black and shitty, but no fluid leaked out anywhere. Your prob does sound like the slave to me, coz the fluid in the reservoir is clean, easy job to do, and cheaper than the master cylinder, so I'd try that first.

 

[MORF114]

Some ****er tried to steal my R a few months ago and they pushed really hard on clutch pedal to snap steering lock (i think) they ****ed the master cylinder the resevoir was full but no clutch pedal no leaks or anything so when i went to drain the fluid out slave nothing came out but resevoir was full (strange) but ive not inspected it yet but we think they pushed so hard it just ****ed it somehow ive just stripped it and had a look inside but nothing to see really apart from worn seals and a bit manky inside so we did a pressure test on the one we took off by putting fluid in it and pushing on the rod there was no pressure at all so ive just put it down to seals, not going to think about it too hard.
Its not a hard job to change master or slave just annoying takes a couple of hours to do master slave i didnt do but looks like a half hour job.

 

[OZ-Racing]

I've changed my mind.
I think my theory about the slave cylinder is wrong, as it is only a single acting cylinder, so if the seal was gone then the oil would have to leak to atmosphere.

My current theory is that it's old fluid, must have drawn in some water (as brake fluid does this) and when it got hot, evaporated to form an air bubble. This air bubble is, of course expanding when getting warm, hence only a problem once warmed-up.
I think that bleeding the system in the conventional 'pumping the pedal with a pal cracking the bleed nipple' approach may not have been enough to push the bubble out. Next step is the pressurised bleed kit, which I will try this week, but only once I have managed to mate the screw cap to our push cap reservoir:roll:

If that doesn't fix it, then it's cylinder time

All good fun :lol:

 

[OZ-Racing]

Hope you're not using dot 3 brake fluid for your brakes too :shock:

I could use lager instead of brake fluid and they'd still be more responsive than yours :shock: before you fixed them;-)

 

[Fast Guy]

It sounds like you master cylinder has gone (My brake master did a similar thing on my last car)

Clutch fluid shouldn' t get hot enough to boil off any water into air bubbles.

 

[OZ-Racing]

Just the fitted repair kit to the master cylinder, which I'm glad I did because it was full of muck, but now it's like new :-D

Unfortunately it has just transpired that the master cylinder wasn't the problem:doh: , still glad I overhauled it though.
After a month of having this problem, when finally going about working on the master cylinder, we noticed fluid streaming down the front of the gearbox :roll: I then squeezed the gaitor on the slave cylinder and fluid came ouzing out.

So here's a tip: If you have the same symtoms as my R with no obvious leaks, give the gearbox gaitor a squeeze. Chances are the fluid's slowly leaking out and gathering in there with no obvious signs.

Right, I'm going to order a slave cylinder seal kit now :roll:

 

[Cambridge_pulsar]

Just get the damn thing fixed for fooks sake, we need to have all 4 running properly at some point, i.e. before my engine/gearbox/suspension/clutch explode into a million pieces! :-D

 

[OZ-Racing]

Just get the damn thing fixed for fooks sake, we need to have all 4 running properly at some point, i.e. before my engine/gearbox/suspension/clutch explode into a million pieces! :-D

Well I should be all hunky-dory by the end of the week, so stop bugging me and get on to Nelson :fu:

 

[Cambridge_pulsar]

I've tried but there's too much :fight2: going on with Neil...

 

[Nelson]

Cockends!!