The clutch saga

Air in the master will act like that.

I do thing you said you didn't bench bleed it?

Some just need to be pumped like mad to get the air out, some have to be perfectly level and pushed in deeper than the pedal can do it.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 (More Off Road album links at bottom of the view page)

I agree. Pull the master and bench bleed it all the way. Sometimes the pedal doesn't quite reach the end of the travel for the master.

HTH

Carl

Alright guys. I'll give it a shot tomorrow and see what happens. It will give me an excuse to get out in the great weather we've had the last two days. Thanks

Let us know how it goes.

Carl

On Feb 20, 10:32 pm, "Carl S" wrote:

I did not bench bleed the master by putting it on a bench, but here is what I did. I took a piece of hydraulic line and looped it around from the hydraulic fitting in the master cylinder back into the reservoir. I disconnected the master cylinder plunger from the clutch pedal and pumped it in and let it release until I didn't see any more bubbles looping around into the reservoir. I then quickly swapped the piece of hydraulic line for the hydraulic line that goes to the slave.

This didn't help much at all. The pedal would get firm while bleeding it, but soon after starting the engine the pedal would not engage until close to the bottom of the stroke and the transmission could not be put in gear. I was skeptical on the clutch line because of issues sealing it earlier, and I guess I like to continue to sink money into this, so I replaced the clutch line. I bled the system, but did not re-bleed the master as above, and the clutch got real firm.

I bled it as follows: I had a friend pump the pedal a few times and had her hold it to the floor. I hooked a vacuum pump to the bleeder valve and built up pressure. I then cracked the bleeder valve just enough for fluid and air to escape. I had a clear tube hooked up to it and fed it into a small container with a couple inches of fluid in it. I did this 3-4 times until the air bubbles stopped developing. I made sure the master reservoir remained full. I then repeated this a couple more times without the vacuum pump and all seemed well (no bubbles).

This seemed like it was going to work out. I started the engine and let it warm up, as it is now cold here again. I went out and depressed the clutch and worked it through the gears. I did this several times. It was working so I thought all was good. I went for a drive and about 5 minutes into it the pedal went almost to the floor before it engaged. I could not get the tranny out of second gear until I slowed and pumped the pedal several times. It then would work OK for a while then it would repeat. I then noticed a pattern. When I replaced the clutch line I only connected one of the 2 bolts that held it to the body (since I wanted to test the clutch pressure before permanently bolting down since the bolts are tricky to get to), When driving I would sometimes here a loud rattle in the vicinity of the clutch pedal area, but on the other side of the firewall. This is also the area where the rubber hose turns to metal on the clutch line, right before bending under the vehicle. The line is slightly different than the original, but not significantly different. I believe the metal of the hose was rattling against the body pretty rapidly, sounding like a bad vibration. At this time if I tried to shift the tranny, the clutch would not have much pressure at all. I observed this pattern continue as I limped the jeep home. Rattling = no pressure. I had issues with maintaining pressure the whole way home. What is weird is that it seemed like it was better when shifting to third, but I couldn't observe a pattern there because I was scared of being stuck in third, so it might have been coincidental that it seemed good the couple of times I tried it. At least in 2nd I could cheat up to stop signs and lights.

When I got home I parked the jeep and went inside the house to wallow. I then came out a few minutes later and pressed the clutch pedal. It was solid as I pressed it. Just like it was when I bled it. Not after pumping either. On the first couple of strokes.

Anybody have any ideas? I feel I replaced the various clutch parts to spec. It seemed rather straight forward. I don't know what to do at this point.

From the details you give, I have to ask: did you flush the whole system? Reason I ask is that I had a used slave/master set when I swapped out the internal slave and the master finally gave up a couple of years later. I installed a new master, let it bleed itself ( the external slave will do a pretty good job of self bleed in half an hour or so since there is no residual pressure like a brake system has). Six months later, I sometimes had a good clutch, sometimes could get it to work by pumping like mad, and a couple of times came home shifting w/o a clutch. When I pulled the master, it was full of black gunk that was messing up the rubber valve in the end of the cylinder and not letting the master prime itself - sometimes.

One thing you never mentioned: do you have to add fluid every so often? If so, you have a leak somewhere otherwise you have a poltergeist on your case.

I haven't driven it enough to ever have to add fluid. I have replaced the clutch end to end in the last few weeks. I replaced the slave, clutch disk, pilot bearing, and pressure plate in one weekend, replaced the master the next weekend, then replaced the hose this last weekend. I haven't been driving during that time recently because of the clutch issue (and it is not my daily driver). I may have gotten a bad master, but I don't know how to tell. I could take the master back to the parts store and try a new one, but I wondered if it sounded like anything else. Especially the way the hose was slapping against the body of the jeep. That seemed odd to me.

Any chance the exhaust is too close to the clutch line?

Any chance the exhaust or the header bellows has a (that) crack in it blowing a stream of superheated exhaust air at the clutch line?

Any soot marks on the old parts?

Was the hydraulic fluid the right kind and out of a freshly opened bottle? Brake fluid can absorb an amazing amount of water which then lowers the boiling point of the fluid 'way' down.

I am thinking your clutch fluid is boiling maybe....

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 (More Off Road album links at bottom of the view page)

I don't follow on how to bleed from the master cylinder or how to go about pushing down the loop. Care to expand on those suggestions?

Thanks

I don't think it is boiling. The line is not close to the exhaust. I will drive it around some more and make sure the line is not hot when it starts acting up. I have flushed the old fluid out in order to eliminate old fluid as the problem.

I flushed the old fluid out of the line today, and while re-bleeding I noticed something peculiar. I would pump the pedal a few times, hold the pedal down, crack the bleeder valve, and let the fluid run out. However, while the fluid ran out it felt like air was rushing in. This would occur for a few seconds. I could hear (sounds like bubbles rushing up the line) and feel it in the clutch line. Small bubbles also formed in the master while doing this. Am I doing something wrong now or does this sound like a component failure?

Every time I have clutch system apart (external slave), I simply bleed before I attach the slave to the bell housing. Get a helper - it's quicker. Crawl under and compress the slave by hand. Have the helper fill the reservoir, then release the slave push rod SLOWLY as the helper keeps the reservoir full. That will just about fill the slave, but it will have an air pocket, so point the actuator rod down and have the helper holler when the bubbles stop OR the level in the reservoir drops all the way down. DO NOT ADD FLUID AT THIS TIME - you are about to push it all back up again any way. Push the rod all the way into the slave - SLOWLY. You probably will get at least some fluid back up to the reservoir - if not, have the helper add fluid and keep it full release the slave rod - slowly. Repeat until the reservoir is full with no bubbling when the slave is full compressed. Release the slave all they way out, make sure that there is some fluid in the bottom of the reservoir at all times - not full, but enough to cover the bottom.

Crawl out and sit in the driver's seat. Have the helper fill the reservoir. SLOWLY press the clutch all the way down. Hold it for a few seconds and SLOWLY release it once or twice. Wait for any bubbles to stop, then press the clutch and release it quickly a few times. Top off and go.

The older external slaves had a bleed valve that made the process a bit simpler, but the new ones (aftermarket) come with the bleed port plugged and no threads for a valve so this is the only way to get a good initial bleed.

The clutch system is not under any pressure when not depressed, so any air will eventually work its' way out from here.

This is a gravity system. You have to open the bleed port before the pedal is all the way down and close it before the pedal reaches the firewall. The line will drain by gravity if you leave it open with no pressure. If it will fit, you can also use the old time method and attach a line to the bleed port and run it into a jar of brake fluid. Fill the hose with fluid, then the system will siphon brake fluid instead of air when not under pressure.

Sounds like you're bleeding wrong. Have someone pump the pedal, then have them hold it down. Crack the bleeder and let it spray out. Close it before the flow stops to prevent air from going back in. Try that a few times and see if that helps.

Carl

What I ended up doing in the end (after trying everything I could think of and that was suggested) was getting a speed bleeder and combined that with the mityvac to suck air out of the bleeder port. I cranked up the pressure to 15 psi, slightly opened the bleed port, and slowly cycled the pedal with half strokes. The clutch is very firm right now and staying that way. I believe it is bled well to this point.

I just drove it around for half an hour and I only experienced a tough shift one time. It was when I heard the rattling metal like sound (see above post about that). As soon as it happened I pushed on the pedal and it did not engage as early in the pedal stroke and the tranny was stuck in gear. I let off the clutch, waited a couple of seconds, and pressed the clutch again and it was firm again and it shifted just fine. I think I am changing my mind on where the rattle is. I believe it is where the clutch line and bleeder line exit the bell housing. Its hard to stick your head by the pedals when you are driving and the clutch wont release, but I tried and it sounds like it is originating from that area. I tightened the hose down along the firewall and of course it does not rattle nearly the same now. There was a rubber grommet of some sort where the hoses exited the housing when I tore it down, and that was the one part I was missing when I put it back together. I forgot I was missing it during reassembly because I was tackling getting the cross member bolted back up and forgot to look for it when I was done. Do you think the lines rattling there could be causing clutch issues, or something is going wrong in the system and the line rattling is just an end result of that? The clutch is very predictable, and will not release, when that noise occurs but I don't know if not having the rubber piece in there is a culprit. Ideas?

Also, I am a little worried about the tranny fluid I am using right now. I am using Mobil 1 synthetic which I believe has additives in it that are harmful to synchros, but the manual called for a GL5 based fluid and that is one the part store had. I am thinking about switching it out after doing seom reading, but I do not know what to switch to. There are a variety of opinions out there. Any suggestions on that?

Thanks guys for the help.

Will