clutch hyd and bleeding- check my work

[steveo3002]

my on going clutch saga i cant seem to get a pedal , ive tried several combos of master /slave , new hose

so i took all the parts in the shed and screwed them to a plank of wood same orientation as on the car , bled it by pushing the rod and cracking the nipple while the slave was clamped to stop movement , in no time i got the master rock hard like i expected , left it overnight still hard , no leaks

fit these very same parts to the car and ive tried pressure bleeding and reverse bleeding with a new oil can , after hours best ive got is it just works and crunches into gear

what on earth is going wrong...if it wasnt spongey on the bench test then that confirms its all good right?

 

[m_c]

It's generally down to the pipe/hose routing having various high points, and is usually overcome by lots of flow, which means lots of pressure.

What pressure were you using with the pressure bleeder?

 

[colnerov]

New? used? rebuilt? re-sealed?

 

[steveo3002]

It's generally down to the pipe/hose routing having various high points, and is usually overcome by lots of flow, which means lots of pressure.

What pressure were you using with the pressure bleeder?

about 20psi which is marked as safe on the gauge, yeah maybe i should try more pressure

 

[Guineafowl]

If you can take all the bits off together, how about stringing the assembly up, with the slave at the top?

If you’ve put in a new clutch plate, you’ll need more throw to disengage properly, and that’s when worn pivot bushings become apparent.

There’s any number of threads on the landyzone forum about TD4 clutch changes, when a new clutch leaves the bite point on the floor, ‘can’t seem to bleed it’. I had it on the two I did. It’s wear in the pivots.

 

[steveo3002]

If you can take all the bits off together, how about stringing the assembly up, with the slave at the top?

cant really get it high enough...i have been trying with the slave off and higher than normal

 

[m_c]

about 20psi which is marked as safe on the gauge, yeah maybe i should try more pressure

I'd try about 30psi. The bit extra pressure might be enough to push any air pockets out.
Another thing to try, is pressure bleed it in reverse. Empty the reservoir, open the bleed nipple fully, and push the pressure bleed hose over the bleed nipple.
I put a pair of hose clamping pliers over the pressure bleeder hose, pressure rise it, take the pliers off until the reservoir is full, then put them back on. The pliers mean you get an instant on/off, rather than waiting for pressure to build/decrease.

 

[steveo3002]

i tried reverse bleeding with a new oil can and some hose

yeah will try more pressure...had brakes that wouldnt bleed once , tried a proper pressure bleeder from work and they bled in seconds , aint got access to that now though

 

[steveo3002]

would you move the pedal while the pressure bleeder is on?

 

[m_c]

would you move the pedal while the pressure bleeder is on?

No. You risk damaging the seals.

 

[steveo3002]

i was reluctant to clamp a brand new rubber hose...

but if i clamp it and the pedal is hard , all is okay upstream of the clamp? if no more master bleeding or faulty master?

if master checks out , then keep bleeding at the slave or its faulty?

 

[Keithmac]

Post a picture of the setup in the engine bay.

With brake M/C's you have to make sure the piston is all the way back in the rest position, if not it will not blead properly.

I've seen time and time again were people have adjusted all the free play out of the adjuster and at this point the cylinder cannot return fluid back properly. The brake pedal gets worse so they adjust more and the spiral continues.

Make sure the master cylinder is at it's correct resting position. It should self blead technically if MC is at highest point.

If your pedal is pre-loading the MC piston then you will never get an adequate outcome.

 

[steveo3002]

its my g60 keith

the pedal is pulling on the master so its fully out when the pedal is up , ive bled it with the pedal not attached too

no adjustments on either part

 

[500e]

Make sure the slave piston is right back in the cylinder, some old Peugeot were bad for this had to back bleed with slave clamped in

Had a Ford once all new breaks would not bleed a gallon of fluid still Minimum pedal pedal, clamped pedal down on what was there next morning bleed again all ok

 

[bricol]

my on going clutch saga i cant seem to get a pedal , ive tried several combos of master /slave , new hose

so i took all the parts in the shed and screwed them to a plank of wood same orientation as on the car , bled it by pushing the rod and cracking the nipple while the slave was clamped to stop movement , in no time i got the master rock hard like i expected , left it overnight still hard , no leaks

fit these very same parts to the car and ive tried pressure bleeding and reverse bleeding with a new oil can , after hours best ive got is it just works and crunches into gear

what on earth is going wrong...if it wasnt spongey on the bench test then that confirms its all good right?

Your test says to me there is something mechanically not right between slave and clutch - push rods not engage correctly, release bearing not assembled correctly, or even (unlikely) crank thrust washers worn out and you are simply pushing the crank away.

 

[steveo3002]

Your test says to me there is something mechanically not right between slave and clutch - push rods not engage correctly, release bearing not assembled correctly, or even (unlikely) crank thrust washers worn out and you are simply pushing the crank away.

its mushy if i take the slave out and clamp the rod in the "in" position

 

[bricol]

No. You risk damaging the seals.

Unlikely. While a clutch system is unlikely to be up in the 1000's psi like a brake system, its still going to be higher than the 20psi from a pressure bleeder.

And as a clutch master goes full stroke more often than not, unlikely to be damaged by dragging over unused parts of the bore - as a specialist claimed my car did when he worked on it . . . never happened before or since in my own work.

 

[bricol]

its mushy if i take the slave out and clamp the rod in the "in" position

You might need to add a bit more detail Piston?

 

[anto44]

Can you post a pic of where the slave cylinder bolts to the box? I've seen similar clutch issues with a lot of vws of that era with a certain setup

 

[steveo3002]

ive tried removing the slave with the hyd still attached , the gold coloured rod on the right of the pic i clamp in the in position with a clamp like so , then i try to bleed it