Clutch bleeding foible...

[eddiealfanut]

Hi,

I know this topic has been covered before, but I hope that this may be of some minor interest to some. Here, it relates specifically to the TS, though it may apply across the range.

I have replaced/removed the slave cylinder on my 75 many times and never had a problem bleeding the system afterwards. I use a pressure bleeding system; one of the cheap and simple ones that you attach to a spare tyre or some such thing. Always worked faultlessly.

Until this time :-)

Anyways I could push fluid through the system no problem, and get good clear fluid out the bleed valve with no bubbles or dirty fluid etc. but the master cylinder would not charge fully, and I was left with about an inch of useless pedal travel no matter what I tried. I ended up using _quite_ a lot of fluid doing this. Eventually decided to scour the old internet before bothering the group for advice.

I found this nice little page Bleeding or Flushing Brake and Clutch Hydraulics
which apart from being nicely written basically says, (a) use a pressure bleeder & (b) make sure the pressure is highish (around 20 psi)

Now this got my tiny brain thinking; I was using a spare tyre to pressurise the system and, to be honest, just assumed it was providing enough umph. Out I go and check it; the pressure was < 10psi. Pumped it up to 20psi, plugged it all in, bled the clutch, two minutes tops. Perfect pedal.

So maybe there's a little kernel of useful info in there. Our clutch systems do seem to be similar to the Volvo one mentioned in the thread above in their need for decent pressure to bleed.

Hopefully that is of some use to someone,

Ed.

[sh0rtlife]

after seeing some seals blown from using a pressure system....ive seen it blow out master cyl seals and spray fluid INSIDE the car, not pretty......a vac system with prepared bleeders works best imo...prepping a bleeder requires removing it and wrapping with teflon tape to prevent the vacuum from pulling air thru the threads

[eddiealfanut]

Hmm.. you could be right.
Luckily I've never seen such blow-out myself to date (fingers crossed).
But, if the pressure required is of a specific level (in order to properly fill the MC), does it matter if it's being generated by vacuum from the bleed nipple, or outside pressure from the resevoir?

Ed.

[sh0rtlife]

with a vac you can crank the presure WAY up and not hurt anything....and you can leave it going while adding fluid to the resevoir

[thesameguy]

I really find the Motive Pressure Bleeder to be the way to go on this stuff... it isn't expensive (US $40-$60, depending on options) and it works beautifully. Really makes an unpleasant task pretty simple...

Also, in a pinch, "reverse bleeds" using a large syringe works pretty well. Fill a syringe with brake fleed, put it on the bleeder on the slave, and squeeze (gently) fluid backwards through the system. A big syringe sourced from a vet supply works very well, and you're done in seconds.

20psi sounds like a LOT of pressure to put into a system, BTW. I've blown out master cylinders using less... 20psi seems like a formula for broken parts.