Clutch hydraulics fun

[FrattonEnder]

I've been doing a bit of hypothesising about how my clutch hydraulics failed over the weekend, so I'm using you guys and a bit of a sounding board.

Scenario is that on the home leg after dropping my daughter back at her uni digs and a rather rapid turnaround (10pm and facing another 2.5 hour journey home on a Friday night), the hydraulics pretty much packed up after hour 4. That was coming off the M3 at the A34 junction. Gear changes increasing heavy and clunky though still had decent pedal pressure. Eventually I had to resort to rev matching to get any changes done. Pedal pressure remained unchanged throughout the drive

So, as we all know, clutch hydraulic fluid is hygroscopic.
My ZT-T up until early January was like a pond on wheels - sunroof drains, say no more. They're sorted now.

Saturday afternoon, I started practicing yoga and tried to pour my overweight, 6'3" frame into the driver's footwell. After much effing and jeffing, I got the cap off the master cylinder reservoir, pulled out the rubber glove-like diaphragm only to find what I could only call a sludgy, mayonnaise-like watery substance. Think French dressing but much less tasty.
Syringe in hand, along with a length of tubing, I managed to get a good amount of this muck out of the cylinder and topped up (and then some) with fresh(ish) DOT4. Hey presto, fully operational clutch with none of the low speed judder I'd been experiencing since I bought the car last November.

Right, onto the hypothesis.
The damp in the car had been absorbed into the clutch fluid.
The four hours of almost continuous driving, coupled with the higher ambient temperatures on Friday, had effectively 'boiled' the water out of the fluid and caused the sludge.

Having had a slave cylinder fail on my ZT, I know what mess can leak out of the 'box casing and there's no sign of that yet. Assuming the couple of shortish test runs I'll do this week don't cause any further issues, I'll run the old girl to the Nano on Saturday - with DOT4, syringe, tubing and plenty of ibuprofen packed.
A full bleed is planned in a couple of weeks - before the load lugger is pressed into long-distance haulage again.

Yes, I know that I'll most likely have to have the 'box whipped off and the slave swapped at some point - I'm just trying to delay that as I've got some welding that needs doing first!

[Mike Noc]

If you had the rubber diaphragm in then the system is sealed - that's what it is for.

[FrattonEnder]

Originally Posted by Mike Noc

If you had the rubber diaphragm in then the system is sealed - that's what it is for.

That's what I thought. The design of it allows pressure balancing on either side through the vent in the cap. However, from what I could tell, there was definitely signs of moisture in the fluid. The previous owner told me that they had topped the clutch fluid up and bled the system (someone who is a recognised expert too) so maybe the fluid they used was 'off'. Who knows.
Anyway, I'm doing short test drives over the next few days to see how things hold up. If I can persuade a 'volunteer' into helping me, I'll get the system bled too.

[suzublu]

Sounds familiar, having gone through similar problems recently, difficulties engaging 1st, changed gearbox oil using a Draper hand pump, which I also used to bleed the clutch. One way valve on the bleed nipple, pumping pedal at the same time as refilling master with new fluid. I now have a lovely light clutch and smooth gearchanges. 😎

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[FrattonEnder]

Originally Posted by suzublu

Sounds familiar, having gone through similar problems recently, difficulties engaging 1st, changed gearbox oil using a Draper hand pump, which I also used to bleed the clutch. One way valve on the bleed nipple, pumping pedal at the same time as refilling master with new fluid. I now have a lovely light clutch and smooth gearchanges. 😎

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Has your clutch behaved itself since?
I'll either go old school and get someone to pump the pedal slowly (after fully topping up the master) while I operate the bleed nipple, or dig out my Easibleed kit and try and see if one of the caps fits.

[suzublu]

Originally Posted by FrattonEnder

Has your clutch behaved itself since?
I'll either go old school and get someone to pump the pedal slowly (after fully topping up the master) while I operate the bleed nipple, or dig out my Easibleed kit and try and see if one of the caps fits.

It's been great since. I used my brake easibleed with a rubber tube over the bleed nipple.

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