Need help with hydraulic clutch

alde

alde

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I am pulling what little hair I have left out:o. I have a 1992 Toyota 4 X 4 pickup with a v-6. A few days ago I pulled out of the driveway and got into 1st and started down the road. I got to 3rd and stopped at the stop sign. At this point I lost the clucth pedel. I could not get into gear. I shut the engine off and put it in 2nd, started the truck and limped home.

I found no leaks in the hydraulic system or the master or slave cylinder. I thought there might be an internal leak in the master but decided to change both master and slave.

I have been trying to get a good clutch now for the last two weeks. It took me a long time to even get fluid out of the master and even longer to get any pressure on the pedel. I have been using one of those bleeders with a check valve.

I finally got to the point that my clutch pedel felt pretty good but still could not disengage the clutch to put it in gear with the engine running.

Today I had a friend help me. I had him pump the pedel 5 times and hold it down while I opened the bleed valve. It spit some fluid and air and I thought we were on the way to fixing it. After that first try with my friend I could not get any pressure on the pedel. It won't even pump fluid through the system with the bleed valve (with check valve) open.

I am thinking vapor lock. I did bench bleed it and was able to circulate fluid through the bench bleed hose while on the truck.

Please help while I still have a few strands of hair:eek:. My wife wants her car back and I need my truck. It should not be this hard.
 
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There HAS to air in the system, or the master is leaking fluid past the seals, instead up supplying pressure to the slave cylinder.

Just because you put in a new master and slave cylinder, doesn't mean they are 'good'.

I've installed LOTS of new defective 'out of the box' parts, including TWO disk brake calipers that were junk, right out of the box.

A hydraulic clutch system is very simple, compared to your brakes. A master and slave cylinder, with a short line in between. That's it


Disconnect the the line from the slave cylinder. Hold a CLEAN finger over the end.

Have a buddy pump the clutch. If fluid doesn't come out under pressure, you have a bad master cylinder, or air in it.

Are you sure you didn't crack the plastic fluid reservoir, when you removed it and replaced it? Verify this, because I've seen this happen, too.

It will let air into the master cylinder, and fluid doesn't always leak at a break.

Also check the linkage between the pedal and the master cylinder, it may not be working right, although it's a pretty simple assembly. Is the yoke still attached to the lever on the clutch pedal?

It's way up on the firewall, and hard to get at to work on, when you replaced the master cylinder, as I'm sure you are aware. Look it over, make sure the adjustment isn't 'backed out' most or all of the way, and that the lock nut is tight.

Set the adjustment for near maximum 'travel', you can back it up when things are working.

Last but not least: you could a broken part inside the bell housing: the slave cylinder MAY be moving, but the parts (...can't remember the right names.....) that engage and disengage the clutch assembly could be broken.

This is what I would be checking if it was my car.

Good luck. This should be a simple repair; I hope you find a simple problem to fix!:confused:

Edited to add: could your bleeder 'kit' with check valve be leaking air back into the system?

I just use clear tubing, and put it in a glass jar with some brake fluid, so the end of the tube is under the fluid. I've been doing it this way for 35 years, since I got one of those 'check valve kits' that was junk. It took me a LONG time to figure out what was wrong!

I've opened up the bleed screw on a brake far enough to leak air into the tubing AND caliper.....but I could SEE the bubbles, in the clear tubing.

You can buy clear tubing in various diameters at a good building supply store: Home Depot, Lowes, etc. If it's a little too small, heat it, not TOO much, with a butane lighter, and press it over the bleed screw. It will stretch a bit. You need a good 'seal' at the bleed nut!
 
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Just a thought. Did you bench bleed the master cylinder?? I know on brakes this is critical when replacing the master, it may be the same for the clutch system.
 
Thanks for the great tips. It gives some new things to look for. One reason I think there is air in the system is that when I had a pretty firm clutch I was able to start it in gear and with the pedel to the floor it would slowely engage and slow the engine down. When it first failed it did it over a few shifts. It got progressivley worse from the driveway to the stop sign and then just would not work.

I really hope there is nothing broken inside the bell housing. I don't think so but you never know. I was also able to watch the lever that goes the slave pushes against move with the clutch pressed. I don't think it was doing it's full travel.

I have also heard of just opening up the bleeder (non check valve bleeder) and letting it gravity bleed for a while. Does this sound like it could help?

I have heard that the Toyota trucks can be a real bear to get air out of the system.

Thanks again for helping with this frustrating problem. It's very appreciated.
 
You changed both master and slave at the same time...That is good!

These things are tricky to bleed. It isn't exactly like a brake system. When you crack the bleeder, you have to close it before the pressure in the line drops to zero. So the first few "cracks" are very short.

The more you bleed it, the more throw you will get in your slave.

Keep at it, and don't give up. And DON"T let the MC go dry while bleeding.

BTW, I have tried gravity bleeding on these systems with no luck.
 
m1gunner, Thanks for the tip on closing the valve before the pressure goes to zero. I did try the gravity bleeding and nothing came out. It's like there is nothing but air in the slave though at one point fluid was pushing through the system. It just crazy.
 
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You MUST use a vaccum pump to properly bleed the system. No other way will work. A Mitey Vac hand pump sells for about $25.
Also check the bracket holding the pedals. I pulled all my hair out on a similar Yota a few years back. Come to find out, the bracket pedal bracket had cracked and wouldn't let the pedal apply a full stroke. A quick pass with the Mig welder cured that.
 
Have you tried pushing fluid in under pressure from the bleed valve? I have used 60 ml syringes with hose-clamped tubing on the end for this purpose.
 
I will get a Mitey Vac on the way home from work tomorrow. I just checked Autozone and they have one in stock at my local store. I will let you guys know how it goes. I think this may be the solution to keeping the rest of my hair:D.
 
I haven't had that good of luck with a Mitey Vac. I was trying to bleed the calipers on a '78 Vette and it would pull air in from around the bleeder screw threads. Always looked like you were pulling air out of the system. I think a pressure bleeder would work better.
 
A jar and 2 pieces of tubing will do the same thing, hands free.

Set the jar up like a suction setup used in an operating room. Punch 2 holes in top of jar, insert tight fitting hose in each hole. Connect one hose to a vacuum port on running engine, connect other hose to brake bleeder. Should have 20" of constant vacuum.

Take $25 you just saved and buy some ammo.
 
m1gunner said:
A jar and 2 pieces of tubing will do the same thing, hands free.

Set the jar up like a suction setup used in an operating room. Punch 2 holes in top of jar, insert tight fitting hose in each hole. Connect one hose to a vacuum port on running engine, connect other hose to brake bleeder. Should have 20" of constant vacuum.

Take $25 you just saved and buy some ammo.
Click to expand...

NO. This will not work. The stroke and volume in a clutch hydraulic system doesn't have enough volume for this to work.
Spend the $25 so you have a vehicle to go and buy ammo and get to the range.

cp1969, sometime the best thing to do with brakes is allow gravity to do the job. Fill the reservoir with fluid, crack the bleeders, and kick back and drink a beer. Been there, done that.
 
scorvers said:
cp1969, sometime the best thing to do with brakes is allow gravity to do the job. Fill the reservoir with fluid, crack the bleeders, and kick back and drink a beer. Been there, done that.
Click to expand...


All good, except this isn't a BRAKE system. You can leave the bleeder cracked for a week and it will accomplish nothing on this particular hydraulic system. They are very difficult to bleed, and this is why some manufacturers sell a complete, pre-bled master, slave, and hose assembly.
 
CAJUNLAWYER said:
I'm voting to take it to someone who knows what they're doing. :D
Click to expand...
If it would drive I probably would have done that. I know it's just air in the system and it's become a bit of a challange.

As far as the air leaking in around the bleeder using the vacume pump, a little thread tape should take care of that.
 
You are best off to start over from scratch. Work from the bottom up!

1) remove & bench bleed the slave cyl.
2) connect it to the fluid line only. Open the line at the master cyl. & slowly by hand push the slave piston to fill the line.
3) remove & bench bleed the master cyl.
4) hook the fluid line to the master cyl. & now install all parts to their propper place.
5) very little additional bleeding should be required. Drive for a few days then check the slave cyl. for air.

All bleeding, go slow to prevent mixing, purge only. NEVER let up on the petal while any line, fitting, or bleed valve is open or loose.

GOOD LUCK! Jim
 
once you have the air out, be sure to check your engine mounts to make sure they are not broken, as this will allow the engine to move away from the clutch rod
 
Picked up the Mitey Vac on the way home from work. Weather permitting I will try it after work tomorrow. It's time for this thing to be fixed. I need to be able to make a guilt free range trip and get some R&R. I have had to work extra hours during the week and half days on Saturdays. I usually get my range time on Sunday morning but have not been able too.

I will let you guys know how it goes. I really appreciate all the help.
 
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