Bad master or bad slave? Which one?

[vtcruiser60]

At this point I think I one of the two is bad, but I don't know which one. I bought a new AISIN clutch master cylinder and slave. I "bench" bled the master, installed the parts, replaced the hard and soft lines, but can't get the air out. I'll bleed it clear, with no bubbles popping up....and let it sit for 30 minutes. It takes several pumps to get a hard pedal....like I am compressing some air in the lines. When I go to bleed again.....I get a blurp of air.

Although these are new, I am thinking I got a bad one? Any ideas?

 

[jus cruzin]

are you bleeding from the master to the slave (pushing the peddle) of form the slave to the resivior (presure bleed)? is the slave adjusted to the correct length throw (ruffly), I usually have more luck bleeding from the slave to the res

 

[vtcruiser60]

Using your language, I am pushing the peddle and bleeding from the master to the slave....out the beeder screw. I have kept the cup full.

I am unsure of what a pressure bleed means, and how to do it....never heard of that procedure, honestly.

 

[jus cruzin]

presure bleed :- fit a pump up fluid canister to the bleed screw on the slave, open bleed, pump fluid canister, extract excess fluid from the resivor. I find it a better way of bleeding, as your bleeding the system in a "closed state", you dont need to pump the peddle and no pushrods need to be adjusted

 

[Fast Eddy]

Although these are new, I am thinking I got a bad one? Any ideas?

That's what it sounds like. If you've still got the old slave, and it works, you could put it back easily enough as a test.

Are you sure you've got the slave output rod adjusted correctly?

 

[vtcruiser60]

A bad one....which one? The master or the slave cylinder...as both were purchased new.

I think the rod is set correctly. i had another cruiser friend look it over as well. It is seated in the clutch fork indent, with a 2-3mm of play.

Also...I DID install the copper washer linking the soft line to the slave.

I am baffled....

 

[Fast Eddy]

When you pump it up, then get a bubble of air, is that bubble right down by the slave, meaning it comes out in the beginning of the bleed? That would seem to imply that the slave is sucking some air past its seals.

 

[vtcruiser60]

When you pump it up, then get a bubble of air, is that bubble right down by the slave, meaning it comes out in the beginning of the bleed? That would seem to imply that the slave is sucking some air past its seals.

YEs...the bubble comes out nearly immediately....followed by solid fluid. You think it is the slave rather than MC?

 

[Fast Eddy]

YEs...the bubble comes out nearly immediately....followed by solid fluid. You think it is the slave rather than MC?

Sounds like...

 

[orangefj45]

first off:

is this in a stock application or do you have a different engine or trans in there?

second:
how did you bench bleed the master?

third:
did you let the system "gravity bleed" before proceeding the the pressure bleed system?

and a couple more things:
after bench bleeding the master, i normally install the hard or soft line ( whatever is applicable ). i do not tighten the line down all the way. have somebody sit in the car and slowly push down on the pedal. you should see some fluid excaping from the loos fitting at the master. at first it'll push out some air, then fluid should start escaping. as the pedal is being depressed slowly and the fluid starts coming out, tighten the fitting.
always pump a hydraulic system slowly. don't get in a hurry with the pedal. this can cause foaming of the fluid and bubbles to get back into the system.
last but not least, while you're pressure bleeding the system, lightly tap both the master and slave cylinders with the handle of a screw driver. both units are made of cast iron and some of the casting will be fairly rough. this can trap air bubbles since it gives them a place to adhere. the shock of tapping the unit will cause them to release and be flushed out.

hope that helps.

 

[vtcruiser60]

first off:

is this in a stock application or do you have a different engine or trans in there?--STOCK SET UP...F ENGINE, CARB, ETC.

second:
how did you bench bleed the master?--WELL, i DID IT AFTER INSTALLATION ON THE FIREWALL. I FIT A PIECE OF BRAKE LINE TO THE CLUTCH MASTER AND ROUTED IT BACK TO THE RESEVOIR. I REMOVED THE CLEVIS PIN FROM THE PEDAL AND COMPRESSED THE MASTER ACTUATING ROD (?) WITH A HAND AND ARM UNDER THE DASH.

third:
did you let the system "gravity bleed" before proceeding the the pressure bleed system?--NO I DID NOT. I'LL LOOK THAT UP AND PERHAPS TRY THAT.

and a couple more things:
after bench bleeding the master, i normally install the hard or soft line ( whatever is applicable ). i do not tighten the line down all the way. have somebody sit in the car and slowly push down on the pedal. you should see some fluid excaping from the loos fitting at the master. at first it'll push out some air, then fluid should start escaping. as the pedal is being depressed slowly and the fluid starts coming out, tighten the fitting.
always pump a hydraulic system slowly. don't get in a hurry with the pedal. this can cause foaming of the fluid and bubbles to get back into the system.
last but not least, while you're pressure bleeding the system, lightly tap both the master and slave cylinders with the handle of a screw driver. both units are made of cast iron and some of the casting will be fairly rough. this can trap air bubbles since it gives them a place to adhere. the shock of tapping the unit will cause them to release and be flushed out.

hope that helps.

YOUR TIPS ARE GOOD ABOVE. AT THIS POINT THERE IS SO MUCH AIR IN THE SYSTEM EVEN AFTER BLEEDING, IT SEEMS THAT IT IS COMING FROM SOMEWHERE. THE AMOUNT THAT IS IN THERE CAN'T BE FROM AN ORIGINAL PROCEDURAL ERROR(MINE) ON INSTALL.

 

[orangefj45]

if this was my rig, then i'd try re-bench bleeding the master. leave the pedal attached and pump it slowly 20-30 times. they take a while to bleed. also, make sure you're getting the right amount of travel on the pedal so there's no chance of the master not being actuated all the way and air being left in there.
then bleed the line at the master as described above.
grvity bleed it next. all ou have to do is to slightly open the bleed screw at the slave and let the fluid drip out. make sure the reservoir stays full. i'd let pretty much the entire contents of a full cup bleed thru that way. make sure you tap the units at this time to release any trapped air bubbles.
now proceed to the pressure bleed. this should definetly do the trick. if not, then i would suspect a bad master.

 

[Pin_Head]

A couple of other things:

Check that the rubber line is not "ballooning".

Bleeding is usually not an issue for clutches as they tend to bleed themselves by gravity. If you have mounted the slave upside down so the bleeder is down, it will never bleed no matter what.

Check that the master isn't leaking internally. Have someone step on the pedal while you peek in the reservour. Any turbulence with the pedal held down is an indication that it is leaking back into the reservoir.

 

[Spud]

A bad one....which one? The master or the slave cylinder...as both were purchased new.

I think the rod is set correctly. i had another cruiser friend look it over as well. It is seated in the clutch fork indent, with a 2-3mm of play.

Also...I DID install the copper washer linking the soft line to the slave.

I am baffled....

Reguarding the copper washer. These are meant to be used once, maybe replace that. Could be sucking a tiny bit of air there. It is a compression washer.

 

[1973Guppie]

are you using new aisin toyota oem units or rebuilt units? I have had issues in the past with rebuilt cheapo units being bad right out of the box......

 

[vtcruiser60]

thanks folks.....I am going to try Georg's steps above...one more time before bailing on this part.

It is a new, AISIN clutch master and clutch slave cylinder. They were sold new from an online AISIN distributor....not the dealer.

 

[vtcruiser60]

Following Georg's steps above, I still have no pressure change in the pedal. I still get a blurp of air after letting it sit a while. Moreover, when I depress the pedal I notice fluid rising then falling in the clutch master cylinder reservoir (Pin Head's #13 comment above).

I am more convinced that I have a buggered clutch master cylinder. Now the hard part of negotiating with the online retailer for a part purchased months earlier. Argh....

Thanks to all for the help and replies....

 

[orangefj45]

yup, sounds like a bad master.......

 

[rukowh]

If it makes you feel any better I'm having the exact same issues with my 60. I have changed a boat load of masters and slaves on several makes over the years and have never had this kind of trouble. I posted abot it a month or so ago and decided it was the slave and bought one from toyota but haven't gotten back to it. Its damn frustrating when you have to wait on ordered parts and they don't work when they finally show up.