Bleeding Clutch Slave Cylinder.

[Late_99_psd]

Hey yall, we put a new master and slave cylinder on the IDI project (91 7,3 IDI if you don't know) and its being a PITA! (of course) We bench bled the system out of the truck and it had no bubbles and felt good and firm, so we put it on the truck and then, boom, air bubbles galore! So we beld it out on the truck and its ok but the clutch dosent engage untill about 2" off the floor.

Do ya'll think that we need to bleed it more and what tips do yall have?

 

[Agnem]

The air gets trapped in the hose. If you have a red hose, shine a light through it and you will see your bubble. If you have the black hose, it's the dickens to get out. No matter how hard you try, the bubble just moves back and forth, never getting out. Start bending the line around, using your X-ray vision to work that bubble up to the top.

 

[Late_99_psd]

Yeah we have the red line (Praise the lord!) and we can't see any bubbles in the line. IDK if there's air in the cylinder itself or what, cause there's no way to adjust the linkage to get rid of some free travel, plus it feels really soft, pointing towad air in the system to me :

We put new o-rings in both cylinders where the lines attach so I wouldn't think it leaking there but I couldn't think of anything else causing air to get in.

 

[lindstromjd]

How did you go about bench bleeding it?

Just throwing this out there, because sometimes the little stuff helps. When I bleed a slave, I always start by putting it on the vehicle, but with the push rod fully depressed into the slave, and not actually mounted up to the transmission yet. So you're holding it in your hands, and then you have someone else fill the master cylinder. Let the push rod out slowly, and keep the master full (because it sucks in a lot of fluid). Then, you just keep pushing the rod in, letting it do all the work to blow out all the air bubbles, and letting it push itself back out. Repeat that process until all the air bubbles are out.

At least that's the way I always do them. The last time I tried to let one "gravity feed" or use a bleeder valve was a complete disaster. It never worked right until we re-did it the way I just described.

 

[RLDSL]

Get a motive bleeder and pressure bleed the sucker just like a dealership would do. No more worries
And once you have that little gem you won't have any excuse to not completely change out all your brake and clutch fluid every 2 years. If you do that you won't ever loose another caliper, wheel cylinder, master or slave again ( this is part of regular scheduled maintnence on most European cars, but they forget to tell anyone on the 'merican makes because they would rather have you rot out your hydraulic systems

 

[redneckaggie]

I had multiple problems with clutch slaves in my truck and I finally talked to brimstone on the phone he was a big help

first you need no ensure that your firewall is not flexing, just a little flex will ruin your hopes of getting it bled,

next you need to make sure your brackets are good and you dont have to move the pedal much to put pressure on the rod

finally remove the slave and tilt the nose up and have someone put slight pressure on the the pedal, dont push it just set their foot on it. crack the bleeder and try it this way, if you have no bleeder then find a way to keep the nose tilted upward and work the slave a 2x4 with a small hole started in it works well, gives you something to rest the rod on so it doesnt slip everywhere.

 

[Optikalillushun]

Get a motive bleeder and pressure bleed the sucker just like a dealership would do. No more worries
And once you have that little gem you won't have any excuse to not completely change out all your brake and clutch fluid every 2 years. If you do that you won't ever loose another caliper, wheel cylinder, master or slave again ( this is part of regular scheduled maintnence on most European cars, but they forget to tell anyone on the 'merican makes because they would rather have you rot out your hydraulic systems

x2, love mine and saved my ass a lot!

 

[tuckerd1]

Get a motive bleeder and pressure bleed the sucker just like a dealership would do. No more worries
And once you have that little gem you won't have any excuse to not completely change out all your brake and clutch fluid every 2 years. If you do that you won't ever loose another caliper, wheel cylinder, master or slave again ( this is part of regular scheduled maintnence on most European cars, but they forget to tell anyone on the 'merican makes because they would rather have you rot out your hydraulic systems

You gave me an idea today. Working on '84 SR5 4x4. Replaced clutch master and slave. Didn't have any help to bleed them. Saw your post and said I can do something similiar with air. I set my air compressor at 10psi and pressurized the MC with air and force bled through the bleeder on the slave. Had a great pedal after about 3/4 of fluid in MC was pushed through the line!

Thanks!

 

[bike-maker]

The bleeder's like mentioned above can also be used to prime the oiling system on a freshly rebuilt engine.

 

[RLDSL]

You gave me an idea today. Working on '84 SR5 4x4. Replaced clutch master and slave. Didn't have any help to bleed them. Saw your post and said I can do something similiar with air. I set my air compressor at 10psi and pressurized the MC with air and force bled through the bleeder on the slave. Had a great pedal after about 3/4 of fluid in MC was pushed through the line!

Thanks!

You just created your own pressure bleeder. Good deal It's a pretty basic principal as you've found out. Trickiest part when doing it that way is keeping the reservoir from running dry, but obviously you figured that part out

 

[tuckerd1]

Trickiest part when doing it that way is keeping the reservoir from running dry, but obviously you figured that part out

It wasn't that hard really. With the low air pressure and I was standing at the MC watching it go down. It went down pretty slow. I would stop occasionally and see if fluid was running into my catch can and when I saw it in the can I was done. Real easy way to do it. Thanks again for the inspiration.

 

[tuckerd1]

The bleeder's like mentioned above can also be used to prime the oiling system on a freshly rebuilt engine.

I've primed rebuilts before using a drill motor connected to the oil pump shaft to pump the oil through the engine. Of course that was on engines where the pump was turned by the distributor off the cam.