Erik765

Thanks again a ton for your help today!!!

See what I mean?!! Maybe if I'm good, I can even take a video of the lever from under the truck and post it later. (after I troubleshoot the hydraulics a bit more). What you're saying about the slave is probably true and exactly what is happening.

Thanks again Banzai510 and thanks Gearshredder, that's the confirmation I've been looking for all along (well, one of them). What I'm gonna do tonight is pull off both the slave and master and bench bleed the master to try to narrow down which may be the issue and then throw a line between them and test. If I remember right, when I had a short line for testing on the master, it seemed to push the fluid really well and the pedal would stop while I was manually blocking the end of the line so, could be the slave too I guess. I'll find out tonight. HRH did offer to help me so I may very well hit him up this weekend when he's free if I can't get it myself before then. My other question that I'm still not sure on is why the lever just moves freely when I manually bring the pin off of it (and when I left the pin go, the lever doesn't push the pin back into the slave). Is it supposed to? In other words, when the truck is running, I can't manually simulate the clutch pedal being pressed by moving the lever (unless I'm just not pushing hard enough). It won't go into gear, period. Thanks again guys! Really appreciate it!

:) Thanks for the encouragement. I'll try that stuff again. One question before I do- by forward, do you mean the push rod extending the fork all the way out? Or having it pushed back in (as if the pedal was not pressed down)? I'll bleed accordingly. You don't think the truck not going into gear while it's running no matter where I push the fork manually is an issue though?

OK. I tried what you said Zeusimo, with the cap off and me pushing the pedal down, there is no noise at all and the fluid in the reservoir doesn't move in the least. There is a little play in the pedal, yes. One thing I have failed to mention, which trumps all else here is that no matter where the withdrawal lever is (if I move it manually, etc.) the truck will not go into gear while it's running. It's not like the rod from the slave pushing the lever all the time means it simply goes into gear. It won't go into gear unless the truck is off, no matter where the lever is. I was told when I bought it that the clutch was iffy and simply needed a slave cylinder (guessing because 'slave' sounds less-expensive to replace than a 'master'...) I thought, oh, that's easy. I can have it goin in no time... yeah... no. Guessing the guy who brought it to me started it in gear (which is currently the only way to move in the truck, then shifted w/o the clutch. It's about a 20 minute drive (in a running car) with about 30 stop lights up and down big hills from where he brought it, to my place. No wonder he was like an hour later than he said he'd be... Problem is, I was working and hardly had any time on a break when he got to my place. I took him for his word, did the deal and off he went (to catch the bus home). So, in other words, I think the hydraulics are in working order, I could even pull off both cylinders and put a line between them to test the operation, but don't really see the need at this point since I'm 99% sure they are not the problem here. I only paid $500 for the rig and the motor runs great, starts immediately, etc. I replaced the cap, wires, plugs, oil and filters and will tune the carb a little as needed, but I still feel pretty bummed (at myself mostly) at this point, lol. Anyone got a rough idea how much I would end up having to pay someone to replace the clutch? Ugh... my little project truck isn't so much fun at the moment any more but I know these things are super cool once up and running so I don't wanna just junk it. Thanks again in advance.

OK, so I got a short brake line and bent it around to flow back into the reservoir and bled that out. Didn't seem to be any bubbles in there, etc. and it pushed the liquid just as I expected it to. Hooked the main line back up, bled the whole system again and the push rod on the slave (control) cylinder still stays out as far as it goes (as far as the withdrawal lever allows it to) when the clutch pedal is let up again. What I've tried so far to narrow this down a bit is pushing the withdrawal lever back into the slave cylinder manually while I have my wife push the clutch pedal. When she does, the hydraulics all seem to work as intended and the push rod comes out and goes as far as it can. I've pushed the push rod back into the slave leaving the withdrawal lever alone and then moved the withdrawal lever back and forth as far as it will go either way. It certainly has no resistance to push either way on its own without the rod up against it. The part that still baffles me is if you push the clutch pedal down, and then let it back up and the slave cylinder rod stays all the way out (which would draw more dot 3 into the system from the reservoir), then if you push the clutch pedal back down again and nothing is moving (rod is still all the way out) where in the world is that dot 3 going? If I'm thinking correctly, I should not be able to push the pedal down if the rods all the way out pushed up against the withdrawal lever. Unless I didn't pay attention in physics class, that one is baffling me to no end. So, all in all, I think Oldskoolvws may be right on this one. Sounds like a clutch, or its withdrawal lever (not the hydraulics). Anyone disagree? If so, please do! Looks like I'm gonna have to pay the shop now and have it towed there (unless you guys can save me here with something I'm missing maybe) :( Whatya think DatzenMike? Anyone? Thanks again in advance. btw, noticed a few guys from Spokane here. Must be a good datsun group in the area. Glad to join it, just hope I can get mine going now!

Yes, there was the push rod that connected to the pedal. I did have a little trouble getting it connected and had to move it quite a bit without and brake fluid it the cylinder. Could I have ruined it you suppose? Also, one thing I'd like to know for sure is why the push rod on the slave is always extended all the way out regardless of what you do with the clutch pedal (like it's expecting or needing to be pushed back in by something). Does the clutch cover plate push it back when you start the engine? If it's always all the way out, where is all the brake fluid going when I press the clutch pedal? (confused on that one). I'm on my way to Napa to pick up some bleeder valves and will definitely re-bleed and start with the master like datzenmike suggested. God I hope I don't have to drop the tranny. I can do quite a bit on my own, but in no way have the means of doing that one solo in my little garage ;( I'll let you know how it goes after the re-bleed. Thanks again for all the input.

Thanks much for your replies. I'll definitely start with the extended bleeding. I'm thinking there may have to be air still due to the fact that the slave push rod pretty much just stays out the whole time regardless of if you push the pedal down (like it's expecting something to push it back once you let the pedal up). Will try a little later and keep y'all posted!

Hello all! I just picked up a '78 620 as a project. The clutch had no resistance to it and did not work at all and I can press the brake pedal to the floor and rotate the front tires with my hands when it's jacked up (different topic)! Other than that, it starts right away and runs really well. I just need to get it fixed so the wife will stop wondering what the heck I was thinking! Anyway, I went down and grabbed a master and slave (control) cylinder and replaced them both, had the wife help me bleed and (here's the super-confusing part) there's no air in the lines (even pushed back the slave and had her watch the master reservoir), but the clutch still doesn't work. There's basically no resistance at all (unless they're just really light and I've never had a Datsun before). I found a good manual (looks like the official repair manual) and have browsed for an answer to no avail. (See attachment for reference). The part I'm not quite sure about, and my main question is- the pin in the slave (control) cylinder is pushed as far out as it should normally go, but the withdrawal lever that the pin pushes doesn't push the pin back into the slave cylinder when the pedal is released... Is this normal? (I hope so, so I don't have a clutch to replace too). I can manually push the control lever on the side of the transmission back but, even w/o the clutch pedal depressed, when I let go it just goes back by itself. So, basically, I'm at a fully new hydraulic system (minus the lines) and still don't have a working system. The level in the reservoir is still at the same since bleeding (no leaks that I can tell). Is it possible the clutch cover isn't pulling off the clutch disc? Is it supposed to? I'm really lost here ;( Thanks in advance for the help and for looking it over!!