Can't shift into gear while engine is running?

[draker]

Since we need more technical content on the site I figure rather than just working through it and solving it.. I would actually document it for the next guy.

69 510 sedan. All stock. L16.

The issue is my 510 has been sitting for about 30 years. The brake and clutch fluid have pretty much dried up and as a result they obviously don't work.

What I've done so far:

Disassembled and cleaned and reassembled clutch master. Re-filled bench bled. Initially it was very difficult to get the clutch to actuate.. but I heard a slight pop and it then actuated just fine. I confirmed the slave is actuating under the car but have yet to measure. It's about 1 inch of travel if I had to guess.

The first thing I noticed was I couldn't shift when the engine was running. Second thing I noticed was the clutch master was leaking into the cab. So I rebuilt the slave with new parts. After new parts and again bench bleeding.. and bleeding the whole system the results are the same. Good slave actuation and solid pedal feel, but can't shift when the engine is running.

My next move is to drain the 30+ year old fluid and refill to the proper level. That's assuming there is actually fluid still in the trans at all.. lol

Also I will measure the slave travel and see if I can find a spec.

[wayno]

Can you put it in gear and then start it?

[draker]

Yeah, I can.

[devilsbullet]

does it stay still if you keep the clutch pushed in, or take off when you start it?

[datsunmike]

I think you've done all you can on the outside.

After 30 years the clutch disc could be rusted to the pressure plate the flywheel or both. Everything else will be, and appear to be, working normally but it's not letting go. I can't think of any way short of removing it to get it apart. Once clean it may have lots of wear left on the friction surfaces.... or not.

BTW the normal travel distance for the slave is 1.18". One inch would be plenty.

[draker]

does it stay still if you keep the clutch pushed in, or take off when you start it?

Nope. If it's in gear the wheels move regardless of if the clutch is in or out.

[draker]

I think you've done all you can on the outside.

After 30 years the clutch disc could be rusted to the pressure plate the flywheel or both. Everything else will be, and appear to be, working normally but it's not letting go. I can't think of any way short of removing it to get it apart. Once clean it may have lots of wear left on the friction surfaces.... or not.

BTW the normal travel distance for the slave is 1.18". One inch would be plenty.

That's kind of what I was afraid of.. but I've got the rear main sitting in my pile of parts that arrived yesterday.. and obviously that was in the plans. Might be dropping the tranny today.

Thanks for the info Mike. Once again, very helpful for me and the next guy.

[draker]

So I am just going to drain the fluid.. see how much comes out. If it's a decent amount, I am dropping the tranny. I'll update in a few minutes.

[draker]

There was plenty of fluid.. but it was super thick.. like melted caramel. Should have been enough to lube the gears enough to shift though. I found a bit of a leak at the slave cylinder though. Will tighten the hydraulic hose and see if that stops. (I replaced it with new yesterday)

Tranny is coming out.

[draker]

2 of 3 exhaust bolts have been broken. shit.. lol

[draker]

Drive line out

[draker]

Actual travel at the slave is .68". Actually quite a bit less than spec.. But the pedal is hard and slave is moving pretty linear. Adjustment at the master would probably give me a little more at the slave. Since I need to do the rear main... I'm going to dig deeper anyway. It's possible a bit of adjustment would dis-engage the pressure plate all the way. But on the other hand .68 might be enough.. who knows. Mike?

[datsunmike]

Well that's almost half what it needs.

[draker]

Yah, just over half. I'm pretty confident that there is no air in the lines.. but I'm not ruling it out. Rear main will be done anyway and it will give me a good look inside. If I don't find anything, back to bleeding. I may have a spare slave around as well.

I got everything removed from the tranny. Ready to remove the tranny mounting bolts and take a look inside. I got pulled away from wrenching around 5.. probably won't have time to work on it again till wednesday.

[izzo]

Ive been across this issue on two different datsuns.

Something is not releasing on the clutch, as mike was saying. Either the disc is welded to the flywheel or something of the sort, or the slave isn't pushing out far enough. I was getting an inch on the slave on a 620, and it was barely enough. Sometimes not enough still. Bled the shit out of the system, swapped masters a few times, different slaves etc. had to of been air in the system or possibly the wrong fork? Dude ended up selling it, and someone else bled the system more and it worked fine.

I have yet to tear into the second one. He is supposed to be dropping it off at my place sometime so I can look into it. Same thing, hits the clutch pedal but cant shift, shut the car off and can put into gear/start the car and it will go. -- 240z -- sat for a good amount of time, nobody knows.

[MicroMachinery]

This happened to me on my 521 after if flooded and the pressure plate/friction disc got wet. Like Datsunmike said, it may very well be rusted together. I tried everything to avoid having to take out the trans, but in the end, I was on my back getting down and dirty. Luckily, pulling a trans on our little Datsuns isn't a difficult endeavor, and can be done in an afternoon. All I had to do from there was remove the pressure plate, and carefully use a screwdriver to peel the friction disc off. After a quick cleaning with some scotch brite, it was back together and working as if nothing had happened.

[draker]

Trans will be out very soon. I didn't have time to work on it today.. but might have it dropped by tomorrow. From the sound it made when I pressed the clutch in for the first time after bleeding... something was fused to something for sure. If I didn't already have to do the rear main, I'd swap the slave and bleed some more. But the rear is leaking and there is oil covering everything. Time for the rear seal and a good cleaning. Oh.... and removing broken exhaust studs. Derp.. I knew the risks before attempting. My only hope is that I can manage to get those studs removed in under the amount it took to drop the trans... lulz. Trans out in 3 hours, studs out in 6.


I'll be praying to the Datsun gods.

[izzo]

May the force be with you draker. You got this shit, yo!

[draker]

I got this shit.

No really.

[draker]

Put in a little more time today and got this out from the car. It's filthy.. inside and out. Obvious rear main seal leak.




Pressure plate was rusted to the clutch disk.



Clutch disk fused tight to flywheel. Unfortunately it couldn't be saved. It's slightly bent.



Either head gasket leaking oil.. or valve cover. Hope it's just the valve cover cause I know that's leaking for sure.



Rear seal leaking.. got it pulled out and new one is ready to go in.



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