Clutch woes, am I missing something?

[galena_sheriff_voltaic]

Hello,

The Mav that I'm restoring had a dead clutch - no pressure at all in the pedal and it just flopped.

Getting under the car, I could see that when I removed the flexihose from the slave cylinder, it was dry and no fluid was coming out, this was despite the plenty of fluid in the master cylinder.

I sourced and replace a new flexi hose, and now there is fluid reaching from the master cylinder, down the rigid pipe, through the flexi-hose and up to at least the slave cylinder.

When I pump the clutch pedal now, there are bubbles in the reservoir so I look likes air is being driven from somewhere.

However, when I remove the bleed nut on the slave cylinder, it remains bone dry.

I must have pumped the clutch at least 400 times (I did this in batches of 50s) and yet the bleed nut in the slave cylinder remains bone dry.

I can hear air passing through the flexihose at times, and each time I pump the clutch, you get a strong bubble in the master. I've checked the bleed cylinder in the master and fluid comes out. I can't see any leaks between the master and slave, and the fluid level is constant.

Is there something simple that I'm not aware of like 'the banjo connector must be at X angle to the slave' or something like that?

I've not worked with a clutch system before so may not be doing something obvious? Can anyone recommend something to try?

Thanks!

GSV

 

[jims-terrano]

Hi, I’m assuming if you’ve replaced parts but have you then bled the system? There’s a bleed nipple on the slave cylinder that you slacken off and let someone else then press the clutch and hold it down while you then tighten the nipple and let the pedal up again. Repeat this until the air is gone.
Also on some models there is a clutch damper pipe. This goes from the flexi pipe to just above the rear axle. This also has a bleed nipple above the axle and again bleed the same way.
However this damper pipe often rots out and leaks or lets air in. A lot of people have found ways to block it off where it enters the flexi pipe.

Good Luck

 

[solarman216]

Hi sounds to me like your master cylinder rubber has gone bad and not delivering oil under pressure, replacement MS is the way forward and I would do the slave as well as both rubbers are likely to be in the same state, Rick

 

[solarman216]

Good point about the damper pipe Jim, I had forgotten about that one, Rick

 

[galena_sheriff_voltaic]

Hi, I’m assuming if you’ve replaced parts but have you then bled the system? There’s a bleed nipple on the slave cylinder that you slacken off and let someone else then press the clutch and hold it down while you then tighten the nipple and let the pedal up again.

This may be the issue - I thought to bleed it you pumped the clutch a few times, then slacked the bleed nipple, but it seems there is a slightly different process.

I will look for a run off the main rigid pipe and see if there is a junction also.

Hopefully, this yields better result. If not, replacement cylinder time I think.

 

[jims-terrano]

Thinking about it if you check the downloads section there might be a workshop guide showing the damper pipe and blocking it off.
Like brakes it normally takes two people to bleed the system and shouting clear messages to each other, just remember that the pedal needs to be held down until the nipple is closed off otherwise it will suck air in from the nipple.

 

[jims-terrano]

Good point about the damper pipe Jim, I had forgotten about that one, Rick

Why on earth they fitted that is beyond me, still mines covered in waxoyl sodoubt it will ever rot out :thumbs

 

[galena_sheriff_voltaic]

Thank you everyone - herself will be deputised to the project!

 

[jims-terrano]

Thank you everyone - herself will be deputised to the project!

Have you managed to fix it?

 

[galena_sheriff_voltaic]

Have you managed to fix it?

Traveling for work at the minute. Won't get to it until the weekend unfortunately.

 

[galena_sheriff_voltaic]

The weekend didn't go to plan, so only got to this tonight.

I pumped it 130 times, opening the bleed valve on the slave by hand, depressing clutch, closing it (finger tight), returning clutch to original position. Repeat.

No change that I could see. However, when the clutch is depressed the fluid level in the master cylinder drops by about half an inch so it would seem there is a lot of air in there.

Is there a link to service manual here? I want to look into that run off pipe and see if that is the problem.

I also plan to buy a little vacuum pump and see if I can force some air out of the lines. I'm assuming that if I'm attaching the pump to the slave, and I can't get it to run fluid, then I know the seals somewhere in it are knackered?

Also, should I be able to move the clutch lever (what the slave cylinder is moving) by hand? Because I can't! No movement back or forward, there is a slight bit of play (half a mil max) side to side

 

[solarman216]

you should be able to push the rod into the slave cylinder by hand therefor forcing fluid back into the master cylinder, if you cannot then it is likely the hose has collapsed/blocked, if on the other hand you can then all of the air will have been vented back into the master cylinder, and the system should now operate, if it does not, then change the master cylinder, Rick

 

[galena_sheriff_voltaic]

you should be able to push the rod into the slave cylinder by hand therefor forcing fluid back into the master cylinder, if you cannot then it is likely the hose has collapsed/blocked, if on the other hand you can then all of the air will have been vented back into the master cylinder, and the system should now operate, if it does not, then change the master cylinder, Rick

There is no forward / reverse travel in the rod.

This is suggesting a knackered slave cylinder?

Edit: Having googled the price, I think I may just replace both master and slave cylinders. It seems they are cheaper than a mid spec vacuum kit.

 

[galena_sheriff_voltaic]

There is no forward / reverse travel in the rod.

This is suggesting a knackered slave cylinder?

Edit: Having googled the price, I think I may just replace both master and slave cylinders. It seems they are cheaper than a mid spec vacuum kit.

Cylinders bought and received.

Will start swapping them out over the weekend.

 

[galena_sheriff_voltaic]

Cylinders bought and received.

Will start swapping them out over the weekend.

Boom! New cylinders fitted and she is working like a charm. Was hoping to take her for a spin for the first time tonight, but herself was having none of it!

Will save that pleasure for tomorrow.

 

[galena_sheriff_voltaic]

And we have movement!

https://youtu.be/HGUyPbQOA3Q

 

[solarman216]

OK the vid works, bit short but looks like your Mav is mobile again, well done, Rick

 

[galena_sheriff_voltaic]

Thanks - delighted to have it rolling.

Next steps, I think, is to the get someone qualified to poke about and make sure the chassis is sound.

Assuming all is good, I was thinking of getting the underneath of her shotblasted and coated. It has spent all of its road life in Ireland, so a lot less salt on the road.

Then time to start replacing brakes, tyres, diff fluids, belts, gaskets (she is leaking oil out of the block and it seems from the turbo ducting a little) etc etc and fix up the simpler issues (broken mirror, bumper is off, grill is missing, etc)