clutch goes, then is ok after bleeding??

hi guys, i had to bleed my clutch again yesterday. probably been ok for over 4000 miles after previous bleed.

can't be leaking as it would slip and be regular loss of fluid.

can go for 100 miles a 1000 miles or more or need doing twice in a week. as i said, has been ok for over 4k miles since last time and still feels ok.

gets to a point where gears start becoming harder to engage and clutch feels like it only has a tiny bit of pressure behind it compared to the gear change before.

now filling the clutch fluid resiovoir requires a syringe and bit of piping which i think puts 1000's of microscopic air bubbles in the fluid which build up to less but bigger air bubbles in the system. only theory i have.

i get no clutch slip its a good strong pull when engaging as i pull a horse box reguarly so when its working its good, just vanishes rather quickly randomly


thoughts lol

thanks jason

Jason, This is a design fault on the TD4, not sure about others ! The master cylinder is not pressed fully by the pedal and hence air remains in the cylinder. I solved mine by removing the master cylinder, simply unhook pedal and it half turns out of bulkhead, then removing the push rod and pushing the piston to the end of travel with a long rod or screwdriver whilst bleeding. Eventually modified the pushrod to give a bit more travel on the pedal and hence lift the bite point up. Please see my other entries on this on this forum.. Andrew

cheers andrew, was getting confusing as pedal travel goes almost in a few gear changes then fine after bleeding. was wondering why it kept doing it, that makes sense now lol, will continue just bleeding when necessary for now. travel with 13 and 10mm spanners and brake/clutch fluid with syringe and spare tubing for on the move bleeding. takes 15 mins even with hot engine lol. down to a fine art.

Hi,
I would change the clutch master cylinder if you are 100% certain that you are not losing fluid. Get one from a breakers as they are pretty bomb proof.
There is no way at all that you should have to bleed the system on a regular basis.
It is either leaking fluid or drawing air into the system.
On the TD4 it is recommended that a pressure bleed system be used owing to the slave cylinder being inside the bell housing.
You also say "can't be leaking as it would slip" ? - why would you think that ? a leak from the slave on a td4 would most likely not cause any clutch contamination at all.
First - bleed it Properly using a pressure bleeder. then -
If there is ANY sign of leaking fluid from the reservoir - even a tiny amount - and no fluid is evident around the master cylinder, - NOTE thoroughly check the master cylinder push rod / piston area under the dust cover for seepage - this is the area that is inside the car !) then it is gearbox out and new slave.

If NO sign of ANY leak at all, and it has been properly pressure bled - then initially suspect the master cylinder as a source of air ingestion - get a cheap S/H one and replace. If this STILL doesn't cure the issue - again it is gearbox out.

This is not a design issue or design fault. It is something wrong on your vehicle.

Joe

after the first few times mate suggested checking pedal and i changed the master cylinder for a new one. thats not leaking anymore. since then air seems to be in system or getting in system and above made sense with the issue of how i'm bleeding it i guess. my mate did suggest pressure bleeding back from bleed nipple but he's busy and costs money lol, guess i'll have to continue my way until i can get him to do it for me.

a garage suggested that if the slave cylinder was leaking it would contaminate the clutch as in bell housing?? no leaks under car.

the last time lasted about 4k + miles, and a vast majority of those are with at least a tonne or more on trailer hitch

61jason61 said:

the last time lasted about 4k + miles, and a vast majority of those are with at least a tonne or more on trailer hitch

Click to expand...

Sounds more like air is getting into the system under certain circumstances.
Pressure bleeding is done from the top of the master cylinder providing you can get a fitting on it. - I have never done a TD4 so have no first hand experience of pressure bleeding it - but that is the recommended way according to Haynes.
Regarding leaking slaves and clutch contamination, very unlikely. The fluid filled part of the slave is fixed - only the 'piston' part moves and pushes the release bearing against the cover plate fingers. Leaks from the slave are not subject to any special rotational 'fling' unless they are directly onto the input shaft - which is unlikely. They will tend to run down the inside of the bell housing causing problems with actuation but not contaminating the clutch. It would often need a considerable anount of leakage to be visible as the inside of the bell is usally coated in friction material dust. The fluid will mix with this and sit there as a goo.... ;;;If you have, say, an oil leak from the rear crank seal, this is a different matter as it tends to touch the rotating flywheel which centrifugally splatters it everywhere .
Back to your issue though. IF you are losing fluid and you cannot see any - then it will be your slave or the inner part of the MC - but you have changed the MC you say ?. - so again - slave.
Was the MC new btw ?
Bleed it properly then if it does it again and no visible leaks at all then replace the master and slave with new components and have done with it.

I would look no further than the two cylinders and a good bleed go for a run for a few miles giving brakes some work then bleed again mine used to last around 4/5 weeks I changed the slave with an after market one and found it was a fault one got it replaced and as been great since