Air in clutch hyd line or...not?

2003 Tacoma 2.4 engine 127,000 miles.
If the clutch doesn't loose pressure while holding pedal down halfway....and if it never feels spongy>>>>can it still possibly have air in the line???
Truck usually gets stuck in reverse when I'm maneuvering on an incline most but not all the time. Truck shudders with clutch all the way in when it's stuck in reverse. I've rechecked the pedal height and bled the clutch hyd system. When on the road, truck shifts just fine.

Also....does anyone know how far the clutch release/arm/fork is supposed to move? Mine moves 5/8". I can't find specs for it in the manuals I have.

Your knowledge is appreciated!!!!!!!!!!

 

One of the best tests for a dragging clutch is to park, shift to neutral, and release clutch. Wait a sec, then press the clutch and immediately shift into reverse. The longer it takes before you can shift, the worse it is dragging. If you can't shift period, it is dragging enough that the transmission input shaft is always spinning, which makes it impossible to engage any gear at all since the output shaft is not moving.

I have generally used 6-7 seconds as a timer. If it takes longer than that before I can shift into reverse, it needs attention. It can drag if the hydraulic system is not working (air will certainly reduce TO bearing travel which will only partially disengage the clutch. It can drag if the clutch itself has warped, or if parts of the clutch material have been damaged or come loose so that the disc is thicker than it should be. Or any combination of other things from bent linkage to whatever.

 

Hey thanks for the quick reply! Half of the time I can shift right into reverse easily...no waiting at all. Always seems when I'm on a slight incline is when it gets stuck in reverse. Drove 28 miles this morning...it all shifted just fine. Got home backing down my driveway and it stuck in reverse again, and with clutch pedal slammed to the floor...it might start shuddering and clutch isn't disengaging, like the truck wants to keep moving.
I've read so many forums about this that I'm dizzy from it all. Maybe I should just get a new master cyl and slave cyl and start from there.
Tomorrow my friend is coming over to help me bleed the clutch system, being I have been doing it by myself.
Thank you!!!!!!!!!!

 

Is it possible that your transmission bell housing bolts are loose? Letting the transmission rock away from the engine/flywheel/pressure plate?

The incline is the interesting part...

 

I'll get under and look if my friend comes over to help bleed the brakes. Interesting thought.
There are no visible leaks at both cylinders, but if one of them is leaking internally....could that cause this problem?
Is there one specific test for each cylinder that can rule out if they're bad?
Thanks Rob!!!

 

Gets stuck going down....or....up an incline. Just drove about 8 miles. Shifted just fine in all gears. Clutch feels good and strong. I tried backing up my driveway and backing down and it got stuck in reverse both times and have to shut engine off to change gears. When stuck in reverse and clutch pedal pushed against the floor....the truck wants to move. We bled the system and no air came out.
This is a drag. Lost in space with this one. Might be forced to pull the trans.....UH!!!!!!!!!!!!
Thanks!!!!

 

That's exactly what it does. Weird.

 

My first thought is about the incline aspect. I don't see how that is going to affect the hydraulics, that seems like a mechanical issue. And the only one I could come up with has to do with the bell housing to engine bolts (not the transmission to bell housing bolts). If you back those bolts off 1/8", then the slave cylinder has to move 1/8" further to force the disengagement. It might not have that extra reach, letting the clutch drag. This almost has to be a mechanical problem.

Another possible idea, suppose the clutch disk fits the transmission input shaft splines very sloppily. Then an incline might see the clutch disk tilt a bit and drag on the pressure plate and flywheel, while on level ground everything is level and that slop doesn't matter.

However, I have seen a loose bell housing cause problems. I have not seen the second issue ever. It is purely speculation trying some retrograde analysis of the form, "ok, here is the symptom, what things could go wrong to cause that symptom?" IE starting with the solution (the symptom) and trying to work backward to the source.

 

That was a great explanation! I appreciate you taking your own time to reply. You talked about moving the bell housing back a tiny bit. What if I put a small spacer between the end of the slave cylinder rod and the clutch arm? But would this mean that the slave cylinder could be bad and not pushing the rod out far enough to disengage the clutch?
When I was bleeding the slave cylinder, every time my friend pushed the clutch down...I could hear fluid squishing sounds in the slave cyl. That's normal I guess.
Thinking again....with the truck on an incline...the trans gears have tension against each other...and maybe a bent shifting fork might not want to cooperate. I don't know.
Thank you!

 

Again, I come back to that incline problem. I don't see how an incline would cause this kind of problem due to a faulty slave cylinder or any of the linkage including the clutch fork and release bearing (throw-out bearing). The incline is the piece of the puzzle that has to be included. And that is the really unusual part of this. I am not even sure the bell housing bolts could cause this with both types of incline. If the top bolts are barely loose, and the bottom ones are very loose, when you park with the nose of the truck uphill, the transmission will possibly try to tilt to sit more level, opening the bottom gap and misaligning the clutch disc with respect to the flywheel and pressure plate. But if you point the nose downhill, that bottom gap would close up and things should be close to correct. If they are loose all the way around I am not sure how it would work correctly when level but not on an incline as with it level, I would expect the tail shaft to drop since all the weight is behind the bell housing bolts, and that would open the gap at the top even when on level ground.

Your "tension" is only there when the engine is dead, the tranny is in gear, the clutch is engaged and the truck is trying to roll downhill against the engine compression. But when you press the pedal, that relieves the tension immediately since now the tranny input shaft can turn and with the brakes off, the truck ought to roll.

Let me recap to be sure I haven't misunderstood anything.

You are parked level, press the clutch pedal, tranny in neutral, and crank it. You can shift into any gear easily and take off.

You are parked on an incline, do the same, but now it won't go into any gear? I would assume you can feel gear teeth sort of grinding when this happens since the input shaft is trying to turn if the clutch is dragging, but the output shaft is locked since the rear wheels are not turning yet.

Does that sound like a reasonable explanation or did I not quite understand something? The above is what I am basing my highly unscientific "guesswork" on, of course.

This goes to show that some proverbs always come true. If you fiddle with automobiles long enough, you will ALWAYS find some problem you have not seen before...

 

You're a deep thinker...I appreciate that.
OK. I just went outside and put the truck through different tests. Now it's confusing. I pulled down the driveway..stopped.. shifted in reverse...backed up to flat spot..shifted to neutral. I repeated same thing...backed up to flat spot and it was stuck in reverse. I repeated it again. This time I could shift out of reverse but it got stuck in neutral. Waited a few seconds and then I was able to shift again.
Now...I backed down the driveway in reverse. I was able to get it out of reverse two different times. Tried backing down again...I stopped on the incline...got stuck in reverse and with clutch slammed against the floor and brake pushed down, the truck was trying to move and it was shuddering.
This is ridiculous HUH! I'll have to wait a few days to pull the trans cause I have a bum leg and my low back is out from sliding under the truck all week.
THank you!!!!!!!!!!!!!!

 

OK. Getting stuck in reverse is not a clutch dragging, if you can't get out of reverse and into neutral. This begins to sound more like an internal transmission issue. My son's 2000 mustang (when he had it) started acting oddly, hard to get in and out of gears. We finally pulled the T5 off and opened it up. What I found was a shaft that holds the internal shift forks in place had either worked itself loose, or someone had loosened it thinking perhaps it was the transmission fill plug. Once it was loose, the shift forks did not work correctly, and eventually we could not get it into reverse at all.

However, that said, when you say that the truck is trying to move with the clutch pedal fully depressed, that's definitely dragging. If the bell housing bolts are tight, I would start with the hydraulics for the clutch. Since it is cheap, I would replace the slave first and bleed carefully. If that doesn't do it, I would replace the master next. And while doing that, make sure that the clutch pedal linkage is tight as well. If the clutch won't disengage cleanly, that ought to be reasonably easy to find and fix. Almost certainly a hydraulic problem assuming that the clutch fork itself is not somehow bent. But if bent, it ought to be consistently bad. You do have the brake master cylinder full I assume?

 

The incline problem could be the air in the line moving......I used to have to bleed my Fieros clutch with the side jacked up for the air to make it's way out.

 

That's what I needed for someone to just say....replace the slave..and then maybe the master. I've been wanting to do it and kept changing my mind. Seems logical to make sure the hyd system is good to go before I attempt to drop the trans. Brake master is topped off. I'll see if I can find the slave locally.
I was just wondering....if saying the word "Slave" is not politically correct these days. I'm sure some one out there will get a bug up their alley and call it racism.
Anyway.....you're allright Robert!!!!!!!!!!!!!!! I'll let you know the latest in a couple days.
Thanks!!!!!!!
Ski

 

Cruxofthebisquit>>>> yeah...that makes sense. I'll keep that in mind when I change the slave.
Thanks!!

 

As others have said, the fact that its trying to pull the vehicle while the clutch is pushed all the way in indicates a problem with the clutch. Could be lots of things causing that, air, bad master or slave cylinder, worn bushings on the release arm, worn throw out bearing, bent (from heat of worn throw out bearing rubbing) fingers on pressure plate, doubled up friction disk materials (due to bits breaking off), or a problem I'm dealing with currently on my 91 jeep snow plow truck, RODENT NEST in the bell housing!

 

That's a good list of the symptoms that could be. I need to start off slow and take Robert Hyatts advice and replace the slave cyl. and go from there.....that is....when my low back decides to cooperate.
Thanks!!!!