Can shift 5spd when not running, but NOT AT ALL when running.

1996 Tacoma 4x4, 3.4 5spd.

Just had a bunch of work done (shocks, water pump, timing belt, tune up) and driving it home from the mechanic, shifting got progressively more difficult, and now I can't shift at all.
Would this be a clutch cylinder issue?

 

Possibly. Just run it back and have it checked. Anything thing short of that is a guess, and a waste of time.

 

The first thing to do is check you clutch fluid.

 

Definitely something within the clutch system, not necessarily the hydraulic side. Look at the reservoir and see if the fluid level is low/gone.

 

Fluid level is ok, but it's dark.

Now this might be completely unrelated but prior to today I did find when shifting from 1st to 2nd there was a noticable thud. Not a clunk, but a thud. That wasn't present today.

 

I always change both master and slave cylinder and it works like new for a lonng time. Seems like whenever I piece meal it, it acts up again shortly. Even if it turns out you need deeper work (probably don't if not slipping) you'll always want a new M/S cylinder anyway to go with new disc.

 

Is something like this an expensive job?

 

Agree on the fluid, I had (stupidly) let my clutch fluid get low and apparently got air in it, got hard to shift. I suggest completely flushing/bleeding the clutch system until it's clear, mine was black too. Consensus is it leaked out somewhere, but everything is dry as a bone.

This may not fix it but it's the least costly thing to start with.

 

You have to look at the throw of the slave cylinder against the clutch fork. If it's not moving far enough you have a hydraulic issue - outside the trans, master cylinder, slave cylinder, etc. Look for fluid leaking out of the master cyl and dripping down the firewall inside by the pedal. If the slave cylinder isn't leaking it's fine.

If it's moving a good enough distance and still have trouble shifting then you have to pull the transmission and inspect the clutch unit for damage - broken/worn out pressure plate springs, bent release fork, etc

That's the fork in the road as far as diagnostics are concerned. How far is the slave cylinder pushrod moving?

 

OK, so things get even more interesting... I just went back out and tried again, now it's working just fine. In fact it shifts quite smoothly on a test drive.
I'm wondering if this is going to be an intermittent issue.

 

I dunno what caused your little hiccup but my experience has always been that to try and get the hydraulic system working better has always led to replacing it. It's not expensive parts.

 

In my case, before I saw the low level, when it was acting up I found if I pumped the clutch a couple times it would shift "sorta okay." I'd still flush/bleed the clutch fluid.