Clutch problems

[JDNSW]

This morning I lost the clutch actuation on my 2a. After checking that the fluid level was unchanged and that there were no signs of leakage, I decided it was either the nuts had come loose on the master cylinder push rod (been there), or the pin on the cross rod from the slave cylinder had broken (again). Having pulled out the floor, and removed the cover on top of the pedal box, neither was the problem. So I then bled it - and got a lot of air out. Now works, but I suspect I am in for more problems.

Guessing that the (relatively new) master cylinder has let some air past the seal.

Any other ideas?

John

(off to finish putting the floor back in - it will have dried off by now after hosing away the fluid from bleeding)

[Aaron IIA]

I had a similiar problem last year. I replaced the slave cylinder and the problem was fixed. It was not leaking fluid out, but was leaking air in. Try checking this.

Aaron.

[JDNSW]

I had a similiar problem last year. I replaced the slave cylinder and the problem was fixed. It was not leaking fluid out, but was leaking air in. Try checking this.

Aaron.

Could be I suppose - the slave cylinder is several years older than the master, although I am surprised that it would let air in as it is always under the pressure head of the column of fluid up to the reservoir. However, one mechanism I can see is that a combination of a sticky slave piston and a rapid removal of your foot from the pedal would result in negative pressure on the whole system, which would tend to suck air past the seals in both cylinders, but primarily the slave since in the master the valve to the reservoir would open.

John

[JDNSW]

Well, its not the slave cylinder. Overhauled it yesterday afternoon - and found that once having the fluid drained, the master cylinder is not pumping well enough to bleed it!

So it comes out today and see what I can do - I don't think I have a spare or even a kit (had a kit for the slave).

John

[JDNSW]

This morning I pulled the master cylinder out. Pulled it to pieces and found that the seals and the bore are in good condition, but there is a fair amount of garbage in it. I think what happened was some of this got under the centre valve, preventing it from building up pressure.

I thoroughly cleaned everything in methylated spirits and reassembled it using rubber grease as necessary. It is now reinstalled and working - all I have to do now is to get the floor back in. Strictly speaking, you don't have to remove the floor to pull the slave cylinder off, but removing the bit of the transmission tunnel over the flywheel housing certainly makes it easier - and removing that means the floor has to come out.

Currently I am having lunch waiting for it to dry off after hosing away all the spilt hydraulic fluid.

John

[JDNSW]

Well, it worked for about 100m. So I pulled it out again, and still mystified as to why it is not working. The centre valve is failing to seal, but I can't work out why.

Yesterday I went into town and took the last cylinder I replaced in to get a stainless steel sleeve fitted. This will cost $130 (about 2.5 times the cost of a new cylinder) and will take at least a fortnight. Meanwhile, the new cylinder I ordered arrived today, and I am back on the road.

Getting to be expert at this - takes about half an hour to change the master cylinder!

John

[MickS]

I've now suffered the same problem John. Driving Basil yesterday, gear changes were getting harder, then no clutch at all. Got it home. Had a look today, topped up master cylinder, pulled the floor out, no sign of leaks....got the clutch back, drove it 100 metres - clutch gone again :(

[Blknight.aus]

lightly hone the bores and pistons with very fine wet and dry. clean thoroughly and treat it to a rebuild kit.

your seals arent working so your not getting a good bleed.

whats happening is when you sort it and put it together your getting a sort of oil seal when you then start the bleed and think youve got it after a while you start sucking air past the main seal, this then gets compressed into the clutch slave and wont return. If you double pump fast enough you can usually get enough fluid down to compress the air bubble and get some clutch back (but not all of it).