97 2wd clutch issues

[Tommy2tone77]

New here , joined in hopes I can figure out what going on with my truck. Installed s new clutch and slave 3 months ago, now I'm slipping, but if I bleed slave, clutch grabs again but only for a mile or so the back to slipping bad, also the clutch pedal bottoms out hard before it should, usually can go to the floor, its stopping 2" prior now and slipping, I just don't understand because it grabs good if I bleed it, but won't stay that way, I get a mile every time, is this a slave issue or is my clutch already bad!? I do drive manual well and never rode clutch or made it slip in any way, I have pressure in pedal, and can shift no problem

 

[RonD]

Welcome to TRS

From your description the Slave is not sliding back into full collapsed position after it was used(expanded), so pressure plate is not pressing clutch disc firmly against the flywheel, so it slips

After its slipping, open slave bleeder, is there PRESSURE in the slave, does fluid SQUIRT OUT?
That's important
If it does then problem could be the Quick connect Valve or the Master cylinder


If there is no pressure, fluid just drips out, then most likely the slave is bad or pressure plate, but slave is more likely
The slave is just a cup with a smaller cup inside, when you press down pedal the master pushes fluid in to the larger cup which pushes the smaller cup out, expanding it towards pressure plate forks, this releases pressure on the clutch disc so its no longer pressed against flywheel
When you release the pedal the pressure plate forks press the slaves smaller cup back into the larger cup, which forces fluid back out of the slave and back up to the master

If the smaller cup is shifting and turning sideways a bit when its fully out, it can get wedged so forks can't push it back in
As you let up on the pedal only some fluid comes back up to master and new fluid is sucked in from the reservoir
So next time you press down on the pedal the slave is still partially expanded so pedal won't go down all the way because slave was already full of fluid
There would be no pressure in the slave if this was happening


The quick connect and the master have one-way valves
The quick connect has a valve that closes when disconnected from slave so fluid doesn't run out of the master and reservoir while it's disconnected
When connected, the valve should open so fluid can travel into the slave and back out to the master

Master has a valve for the reservoir, it is closed when pedal is pressed down so fluid can only go to the slave
When pedal goes up fluid can be sucked in from the reservoir to replace any lost fluid if there was a leak in the system
If either valve was blocking fluids return to master then there would be pressure at the bleeder


Do some more testing to see what you can find out

 

[Tommy2tone77]

Welcome to TRS

From your description the Slave is not sliding back into full collapsed position after it was used(expanded), so pressure plate is not pressing clutch disc firmly against the flywheel, so it slips

After its slipping, open slave bleeder, is there PRESSURE in the slave, does fluid SQUIRT OUT?
That's important
If it does then problem could be the Quick connect Valve or the Master cylinder


If there is no pressure, fluid just drips out, then most likely the slave is bad or pressure plate, but slave is more likely
The slave is just a cup with a smaller cup inside, when you press down pedal the master pushes fluid in to the larger cup which pushes the smaller cup out, expanding it towards pressure plate forks, this releases pressure on the clutch disc so its no longer pressed against flywheel
When you release the pedal the pressure plate forks press the slaves smaller cup back into the larger cup, which forces fluid back out of the slave and back up to the master

If the smaller cup is shifting and turning sideways a bit when its fully out, it can get wedged so forks can't push it back in
As you let up on the pedal only some fluid comes back up to master and new fluid is sucked in from the reservoir
So next time you press down on the pedal the slave is still partially expanded so pedal won't go down all the way because slave was already full of fluid
There would be no pressure in the slave if this was happening


The quick connect and the master have one-way valves
The quick connect has a valve that closes when disconnected from slave so fluid doesn't run out of the master and reservoir while it's disconnected
When connected, the valve should open so fluid can travel into the slave and back out to the master

Master has a valve for the reservoir, it is closed when pedal is pressed down so fluid can only go to the slave
When pedal goes up fluid can be sucked in from the reservoir to replace any lost fluid if there was a leak in the system
If either valve was blocking fluids return to master then there would be pressure at the bleeder


Do some more testing to see what you can find out

Thats and awesome rundown on how the system works, much appreciated! I have bled this thing sooooo many times, sometimes nothing comes out even though there is fluid in reservoir, sometimes it dribbled out, sometimes it shot out pretty good, sometimes it was just barely more than a dribble. The first time this happened, I bled it and I didn't have any issues for almost 2 months, then I started feeling a difference in clutch pedal and I knew I would be losing my clutch, and I did very shortly after and I started slipping while on the freeway. As I mentioned the clutch and slave are 3 months old, I didn't think I'd be having problems this soon. Clutch was slipping when I got the truck. Since the clutch and slave are fairly new, I'm thinking replace the master? they sell them pre filled so i don't have to fight that air bubble.

 

[RonD]

New means "NEVER tested" now-a-days, so grain of salt on just assuming new means it works

You can pay extra for "tested" parts, that's why Motorcraft(Ford) parts cost so much more, or Delco-Remy(GM) parts
Car makers want all the parts tested before installing in new vehicles, but even then there are "recalls", lol

Yes, might as well swap out the master/reservoir to see if its solves the problem

 

[Tommy2tone77]

New means "NEVER tested" now-a-days, so grain of salt on just assuming new means it works

You can pay extra for "tested" parts, that's why Motorcraft(Ford) parts cost so much more, or Delco-Remy(GM) parts
Car makers want all the parts tested before installing in new vehicles, but even then there are "recalls", lol

Yes, might as well swap out the master/reservoir to see if its solves the problem

I've got a pre filled master ordered, fingers crossed it works, I'm missing a lot of work over this