Mystery Clutch Clutch/Hydraulic Problems

[krmccour]

Towards the end of last year, for about 2 months, I started having difficulty shifting gears. It began with shifting into 1st or reverse from a stop, then moved on to the other gears. Eventually, it gave out completely and I couldn't shift at all. Rev-matched it home with no issues. The clutch has never slipped on me, and the runner only has 150k miles. It rev-matches smoothly into gear. Trans has always had Redline MT-90 in it.

I bled the master cylinder(MC)/slave cylinder(SC) fluid and it shifted notchy into 1st, then wouldn't go into any gear again. Made my think master/slave cylinder. So I replaced both, bled the system, and adjusted the clutch pedal. Shifted fine for a week or so, then it became difficult to shift again, and within a day I was back to being unable to shift. Re-bled the system. Worked fine for a day or two, then back to no shifting. Re-bled, worked fine for a day or two, then back to no shifting. Checked the lines, they looked good. No leaks from the new MC or SC.

Thought maybe I got a MC with bad internal seals, so I ordered another. Replaced, re-bled, readjusted pedal (did this today). Now, it will only shift into first if I apply as much pressure as I can to the pedal, and even then I have to push the shifter firmly and it's notchy going in. The remaining gears aren't bad, with the higher gears shifting somewhat normally. I adjusted the MC pushrod so it is as long as it can be. If I could push the clutch pedal another half an inch, I think it would shift into gear smoothly again, but I feel as if this is just covering up an underlying problem.

A few extras: If I start it in gear with the clutch depressed normally, it does not try to take off. I don't have any strange sounds coming from the transmission with it in or out of gear. I HAVE had a squeaky clutch pedal bracket for almost two years now, but I assume that it's that plastic bushing and wouldn't affect pedal travel. There has been times when I've bled it, still couldn't get it into gear, left it overnight, and it would magically go into gear the next morning and would shift (sometimes a little notchy) anywhere from 1-2 shifts to ~20-30 shifts before giving out again.

Any ideas? This has had my runner garaged for the past 3 months or so, and I hate not being able to drive it. I am putting off pulling the transmission out until I rule everything else out. It's not consistent enough to be a bent/worn out clutch fork, it has never slipped so I don't think it's the clutch, I don't get any noise with the pedal pushed in so I'm not thinking throw-out bearing. Surely I wouldn't get two bad MC's in a row. Re-bleeding makes gives me about a 60% chance of it shifting into gear, but only for 1-30 shifts (random) before going out again. If it is hydraulics, then why would it not go into gear, then go into gear the next morning without any change? I'm at a loss.

 

[MyHigh]

Okay, so you are getting a good seal no air in the line from master to slave right?

Something you might want to check, I had a similar problem last year, trans started to get real picky when I had to shift, that's how it started. So to buy some time I would throttle the gas to match the speed and slide into gear, instead of all the pressure being taken off the trans by the clutch.

Then it got real bad!!

Turns out I had a hairline crack where the slave mounts onto the bell housing. So whenever I pressed the clutch peddle the slave would push the pivot fork just slightly and the rest of the force pushed the housing flexing everything but the fork.

To be honest I know of no way to diagnose this by yourself, due to back injury I wasn't about to try and crawl under my rig, instead opting to pay a tech to diagnose what was wrong.

P.S. That housing, which mates the trans to the motor, was 900 from toyota dealership, but I got lucky and got a used one from a yard for 200. Still pricey but not anything like the bend over and cough from the dealer.

 

[krmccour]

Yeah, I've watched the slave while someone pressed the clutch, and it stays where it should. I'm going to check the clutch pedal bracket for any cracks, but I think that was a problem in the 2nd gens.

 

[JimG]

This sounds very familiar to a posting not that long ago. Before you do anything else use the search and find a thread where there is a copy of the FSM on how to adjust the clutch pedal and try that first. Also the bushing where the shift lever goes into the tranny wears and can cause problems like you're describing. There are lots of threads here on how to fix that as well.

 

[slomatt]

It sounds like you clutch might be dragging, that would make it difficult to get into 1st and somewhat easier to get into higher gears. On some cars this can happen if the clutch fork punches through at the pivot, but since bleeding the clutch helps (temporarily) that is probably not the problem.

Could you have a leak in a clutch line somewhere? Do you see any change in clutch fluid level or color over time? If the hydraulics are tight and the master/slave cylinders are new, then it sounds like some kind of mechanical issue such as flex at the pedal. Not a fun one to track down.

- Matt

 

[krmccour]

It sounds like a previous thread because I started that previous thread! :roll:
I followed everyone's advice on that past thread, but still haven't found the problem so I created another one with an update of what I did, what I found, and what's going on now. I really appreciate all the help, I wouldn't have gotten this far and learned this much without it. I'm not terribly upset about the possibility that I replaced a functioning MC/SC, as they would eventually need replacing anyway, I just really need my runner road-worthy as my other car is more of a "project" than a DD...

Adjusting the clutch is straightforward and logical, but I still tried all different combinations of length and freeplay to no avail. So it's definitely not the adjustment. I have NOT checked that bushing where the shift lever goes into the tranny, I will check that as soon as this blizzard stops! In fact, I vaguely remember hearing squeaks in that area when the pedal is depressed...Thanks JimG :bravo:

I haven't seen any fluid loss, although the fluid was an 3/4 inch or so low before I started replacing things. I hadn't checked it since I bought it over 2 years ago, so it could have been like that for awhile. I didn't notice any leaks at the old slave cylinder either.

Does the clutch normally need increased pressure over it's lifespan? This could be why it started gradually, engages near the floor (whenever I can actually get it into gear) but doesn't quite explain why I can sometimes bleed it and shift it for a short time. Although I will say that bleeding it hasn't really helped as much lately as it did when this problem first started.

 

[krmccour]

Although if it was the shift bushing, the transmission wouldn't grind like it does when I try to put it in reverse...it would just not go in...

 

[clemson4r]

Have you thought about the bars on the clutch pressure plate where the throw out bearing rides? I've seen where they will lose their ability to spring back and remain permanently relaxed making it difficult to disengage the clutch or shift into gear.
Max

 

[krmccour]

It could definitely be that, but I was just trying to exhaust all my options before tearing into the tranny itself. I've done lots of mods/maintenance, but have yet to drop and open the trans so it'll probably take a full weekend at least to finish it up. Anyone have personal experience on how long this would take? At that point I'd be putting in a marlin heavy duty clutch kit.

 

[clemson4r]

It could definitely be that, but I was just trying to exhaust all my options before tearing into the tranny itself. I've done lots of mods/maintenance, but have yet to drop and open the trans so it'll probably take a full weekend at least to finish it up. Anyone have personal experience on how long this would take? At that point I'd be putting in a marlin heavy duty clutch kit.

I just did a clutch on mine (OEM replacement, not Marlin) about 6 months ago. A trans jack is very helpful if you plan to pull both the trans and t-case together. Even with flywheel machining and such, it was only a ~8-10 hr job, depending on how quickly you work.

Max

 

[krmccour]

Just wanted to give everyone an update. Shout out to Marlin Crawler for listing what the normal clutch fork movement should be! Normal is ~5/8 inch, mine was moving less than half an inch, so I wasn't getting enough pressure in the system to move the clutch fork far enough. Thankfully this has helped me rule out trans issues. I've bled this system at least a 6-8 times now over the past few months, with varying amounts of success, but I've heard stories from other toyota guys that these can be a huge pain to bleed thoroughly. I just bought a speed bleeder for the slave to make my life much easier than the 1-man bleeding, and hopefully it will be better than cramming tubbing over the bleeder and hoping for a good seal. Going to try one more good bleed with brand new fluid today and see what I can accomplish. Thanks for the advice everyone!

 

[Chuckles89]

I had this same problem. I bled it and adjusted it several times and finally got it to work permanently. Each time I adjusted it, it worked fine until a few days later and a heard a popping noise when I pushed the clutch in. That was from me not tightening the nuts enough on the part of the master cylinder attaches to the pedal. Hand tight will not work on that, so if you haven't used a wrench, I would recommend you to do so.

Hope this helps,
Chuckles

 

[JimG]

It sounds like a previous thread because I started that previous thread! :roll:

Well at least I'm paying some attention . . . LOL (even if not quite enough)

 

[MyHigh]

So are you back on the road yet?

 

[krmccour]

I had it vacuum bled by a local mechanic since I was tired of crawling under my runner in freezing temperatures to bleed it. I'm finally getting enough pressure to shift gears, however I'm still having some issues. :shrug:

When I first began to suspect something was wrong last year when it would grind into gears, I noticed a whirring sound coming from the transmission when the clutch pedal was pressed. At the time, I thought throw out bearing. However, I replaced the MC/SC first since the fluid levels were low and since it was a far easier fix than a TOB. Now that all of these clutch hydraulic issues are solved, and I can finally shift gears again, I noticed the whirring sound has gotten louder.

Currently, about half the time I try to shift it into first from a stop it grinds or doesn't let me in. I have to put it into second and back into first OR lift the clutch pedal up and press it back down again OR press the clutch pedal through the carpet (use all of that leg strength). I was thinking synchros, but letting the clutch pedal back up and depressing it again doesn't change anything with the synchros, so I'm thinking something with the TOB/clutch/pressure plate/clutch fork.

At this point I'm thinking I had a perfect storm of issues, with the hydraulics failing at the same time as or because of the bad clutch/TOB/pressure plate. Right now the symptoms are: clutch engages about 1/2 inch off the floor, often grinds into 1st or 2nd, shudders if I don't give it the PERFECT amount of gas on takeoff from a stop (extremely narrow engagement point, almost always shudders if I'm on an incline, regardless of the amount of gas I give it), and whirrs loudly through 90% of clutch pedal travel (basically as soon as the SC starts pivoting the clutch fork). If I smash the clutch pedal to the floor when I'm having trouble shifting into first gear, it works better (given that the SC movement is normal, that means the clutch fork isn't transmitting the movement correctly, or that the clutch is not disengaging correctly with normal amounts of pressure).

Looks like I'll be dropping the trans. Ready to order the following:

MC Clutch kit (clutch, pressure plate, release(TOB) bearing, pilot bearing)
Shift lever bushing (because why not, while I'm in there)
Output shaft seal (because why not, while I'm in there)
Possibly a clutch fork (because why not, while I'm in there)
Anything I'm missing, while I'm in there?

An Aisin clutch kit runs around $225. I only do occasional off-roading, with nothing too heavy because she's my current DD so would the MC really be worth the extra $100?

On a side note, how easy should it be to move the clutch fork? I have a gut feeling that the bad TOB or clutch is making it much more difficult to move, which possibly wore out my MC/SC faster and started all these problems in the first place. I can barely get it to budge by hand (if at all), and the last 10% of clutch pedal travel requires a lot of force.

Lastly, because I've gotten so much help and because of all the emotional pain I've suffered (lol) from this, I'm going to create a detailed write-up with lots of pictures showing the clutch job. I know there are a couple decent threads out there, but they aren't all inclusive and I'm a visual learner anyway. I'd like to include all my symptoms and any other advice from other members. Shooting for a sticky! :fro:

 

[MyHigh]

Man what a pain in the ass!

Sounds like you have a solution though, get all new parts and drop it. FYI, this sounds freakishly familiar... With the problems I had, time will tell though. Like I said before I had a tech do the work for me and he wasn't able to see what was going on till he replaced everything and still it didn't fix the problem, only then did they realize the bell housing had a crack that flexed and didn't allow proper extension of the fork.

I don't know how much pressure is needed to flex the pressure plates, I would imagine it's a lot though, because you have a master cylinder that increases the pressure for the slave to push out the rod. I'd imagine it's at least more then what you could do with let's say your hands.

Good luck man, I truly hope it's not the same problem I had.....

 

[krmccour]

Well, my 92 Celica convertible decided to start running rough yesterday, and it was my DD while my 4Runner was parked. So this changes my plans a bit since I need a vehicle to drive. Taking the 4Runner to the mechanic next week to have the clutch and all replaced, $600 with flywheel resurfacing (I bought the parts already). Doesn't seem like a bad deal.

MyHigh, if I didn't have that whirring when the clutch is depressed, I would be wary of a hairline crack. I'm honestly still not sure if it is the clutch/TOB/pressure plate, but at this point I don't know what else it could be. I don't understand why it shifted decent (still not back to normal) after I had the lines bled, but it has gotten progressively worse since then and is REALLY tough to get into first now. It's done this same thing before when I bled the lines, it would shift decent for a few days and then go back to nothing. I DID notice that the slave bolts were loose last time I personally bled the lines, but I figured it was negligence on my part to secure them properly. I'll check to see if they are loose again. If they are loose, there has to be a crack because I used locktite and a torque wrench to make sure they wouldn't budge. Still though, I'm getting that whirring from the TOB, so something else is going out. Sigh...when it rains it pours.

 

[krmccour]

So I've got one final update to this thread, and I want to thank everyone for the help I received. I learned more about this transmission than I ever imagined I would, but due to time constrains, 14" of snow, and no garage, I took it to the local mechanic to pull the transmission out and take a look.

Turns out TWO of the pressure plate forks had broken off and did a fair amount of scratching to the inside of the bell housing. In addition, they cracked the flywheel all over, and did some damage to the clutch. The throwout bearing somehow evaded most of the damage though. This explains why it would randomly shift ok and sometimes never shift at all. Also why it always seemed to shift better when the hydraulics were freshly bled, due to that little bit of extra pressure on the remaining pressure plate fingers. Anyway, I have a new Exedy clutch kit and LOK flywheel going in tomorrow, so hopefully I'll be back on the road and shifting smoothly by Thursday!

He's giving me all the parts, so I can post pictures of the carnage if anyone wants to see

 

[davidch]

I just installed a clutch on a recent acquisition, a 2000 V6 with about 180k on it. The new clutch (Aisin kit purchased on Amazon), and urethane seats from Marlin Crawler, made a remarkable difference in shifting smoothness and precision.

I changed another part, I'll call it the shift tower, after determining that it was badly worn. It may escape the attention of someone doing a clutch repair. It's easy to replace, though a bit costly, about $60. Here are two photographs.

http://www.toyota-4runner.org/attachment.php?attachmentid=144882&stc=1&d=1423026792

I think the previous owner had leaned on the shift lever with such force and so many times - it was very hard to shift, even with the clutch pushed well into the carpet - that the left pin in the shift tower worked loose. In the 2nd photo you can see that it's slightly askew. I can turn the pin with my fingers and feel the wiggle.

Now, a slightly sloppy pin may sound like no big deal, but the pin of course is the fulcrum for the shift lever, and down inside the gearbox that small wiggle is multiplied to a big wiggle. I won't make size estimates because I took no measurements.

Furthermore, being loose there was a significant gear oil weepage at that spot.

So, something else to check on a clutch job.

That tower, which Toyota calls "RETAINER SUB-ASSY, C" has a part number of 33506-35140. (R151 gearbox only) To my surprise, it came with a new - and greased! - rubber seat. The breather tube must be extracted from the old tower and installed into the new tower.