Topic: Clutch not working in cold temps

[83MT]

Here's the problem- last weekend I drove to a friends at about -9 F. A couple hours later, I couldn't get it into gear. Would grind when I tried reverse, and just wouldn't go into any forward gears. Towed it home & thawed it out, figured maybe moisture in the clutch fluid? So I completely flushed to clutch fluid. The temps went up, but it was working in single digit and just under zero weather. Then this past weekend, same thing. When I drove it out of the garage I noticed that the clutch wouldn't engage until the pedal was all the way up, but it was working. Parked downtown, and a half hour later, won't go into gear. I turned it off, put it in first (works fine when the engine's off) and started it back up. I limped it home in 1st and 2nd, but the clutch was slipping bad.

I drove it to work today, but again the clutch is only engaging when the pedal is all the way up off the floor. The clutch is brand new, new release cylinder, fresh fluid, so...master cylinder? Something f'ed up in the actual clutch line? I used a hand pump to flush the fluid, just kept adding fluid to the reservoir so no air got in and pumped until I had fresh fluid coming out. That should take care of that, right?

So, if it's not the actual clutch, it's either the master or the clutch line. Could a small kink in the line only show itself when it's cold out? If it's the master, has anybody rebuilt one? It looks super simple in the FSM, but it says to get the piston out with compressed air, which I don't have. Anybody got a trick to get it out without air?

Any advice would be great.

[79coyotefrg]

adjust the clutch, sounds like you need to make the adjustment rod on the slave shorter, fork should have like 1/8 inch of play at the slave rod

[83MT [OP]]

Yeah...but it's been working fine for the last 3 months. Worked fine Wed-Friday, too. You still think the rod is too long, though? Thanks for the reply.

[madhunt]

sounds like the clutch disk is in backwards

[83MT [OP]]

Ok so over lunch, after parking it, it won't go into gear again. And it's around 10 degrees today so not that cold, so it's getting worse.

Long story short I figured out that if I turn it off, put it in gear, turn it back on, and push the clutch in really hard, it will creep forward. I can shift if I only push the clutch in about half way or less. Once it's in all the way it starts to engage. When the pedal's all the way out it doesn't do anything, doesn't even try to stall. I crawled home by pushing in the clutch as hard as I could, and using 4lo helped. So....master cylinder? No major leaks that I can see, inside or outside of the cab, but it's clearly a hyrdaulic system issue, no?

Just noticed your post madhunt. Would it work fine for 5,000 miles & 3 months with the disc in backwards then act up? Doesn't seem like it...but I'm no expert.

[Plekto]

When the clutch is good but the pedal is not, it's usually the master or slave if everything was working beforehand.  Note - the fork could also have bent or messed itself up as well....  (ie - not the trans but the crap attached to it)

[83MT [OP]]

Yeah, didn't think of the fork. I still think that's not it though, since it only showed itself in really cold weather, got completely better, then started to steadily get worse. I put in a new master cylinder last night, but my heater ran out of gas & I got too cold before I could bleed it, so I don't know if that did the trick or not. I'm planning on bleeding it on my lunch break & we'll see if that was the deal! Thanks for the help.

[83MT [OP]]

Replaced the master cylinder. Seems to have done it. The clutch now engages really close to the floor though, and there's a lot of play at the top of the pedal.

I've been bleeding it using a hand pump. Is there anything to that other than hooking the hose up to the bleeder valve and pumping, making sure I keep fluid in the master reservoir so no air gets in? I kept seeing some air bubbles coming out of the valve, no matter how long I pumped. I finally figured it must be sucking some air past the threads on the bleeder valve and that's where the air bubbles were coming from? Or is there something I'm not doing right? Anyways it seems as though the master cylinder was the problem, now I just need to fine tune things.

[83MT [OP]]

Nevermind I'll just try the FSM method of bleeding and adjust the pushrod and bit and see where that gets me.