Toyota Transmission Saga (hydraulic clutch)

[SirNik84]

My friend has a 2WD 1990 Toyota pickup. I did a clutch job for her about 2 months ago. then last week her transmission was acting up. popping out of 3rd and 4th. grinding going into 3rd and 4th. with 3rd being worse then 4th. I diagnosed this as bad syncros and suggested we swap out the transmission. The transmission was only a 4speed, and I suggested swapping it for a 5 speed. This last weekend I swapped out the 4 speed for a 5 speed sourced from a junkyard (with a 100 day warranty). I then took it for a test drive and its popping out of 3rd and 4th. grinding going into 3rd and 4th. with 4th being worse then 3rd. 1, 2, and 5 work fine.

Yesterday my friends neighbor heard about the problems with the new transmission and took a look... he says the slave cylinder is bad because some times it extends fully and some times it does not extend fully.

I would love to change out the slave cylinder and have it solve this problem, but I have been thinking about this all morning and I've got a few questions that makes me think his diagnosis seem fishy. I need a second opinion from some mechanically oriented minds.

If it were the slave cylinder wouldn't their be problems in all gears not just 3 & 4?

he visually saw this slave cylinder not fully extending. that being said, wouldn't the slave cylinder be leaking if it were bad? The peddle feels the same so that fluid has to be going somewhere... and if its not pushing out the rod then its got to be leaking..... OR is it a master cylinder problem and the fluid is leaking back into the reservoir?

I'm thinking this sounds like a master cylinder problem? any other thoughts?

you can get a slave cylinder for the truck for less then $15 and the master cylinder is around $40

I'm inclined to change out both master and slave cylinders and solve the problem of the rod not coming out all the way, then drive it and if the transmission is still acting up, get a new one under the warranty.

[DieselPaul]

For the master cylinder get in the cab and look under the dash. When the master cylinder fails the rear seal goes and they leak backwards into the cabin. Have you verified that the system is well bled? I like to gravity bleed clutch hydraulics.

[SirNik84]

Yeah, I'm going to bleed it. the fluid is goose.

I'd like to plug the line coming from the master cylinder and feel the peddle not move.

[Mike D]

Originally Posted by SirNik84

Yeah, I'm going to bleed it. the fluid is goose.

Ehhh?

[benhogan]

No. You can have a bad master cylinder or slave cylinder even without losing fluid.

This happens when the piston seal is bad and the fluid simply goes around the piston. No fluid is lost. There is good pedal 'feel' but not much work is happening because the brake fluid simply moves around.

I suggest replacing both the master and slave together. If you only do one, the new one will make the old one bad. Replace them both.

I think this will solve your problem. Doing this is easy enough for a toyota truck.

[SirNik84]

Originally Posted by benhogan

No. You can have a bad master cylinder or slave cylinder even without losing fluid.

This happens when the piston seal is bad and the fluid simply goes around the piston. No fluid is lost. There is good pedal 'feel' but not much work is happening because the brake fluid simply moves around.

I suggest replacing both the master and slave together. If you only do one, the new one will make the old one bad. Replace them both.

I think this will solve your problem. Doing this is easy enough for a toyota truck.

I agree that they should both be changed at the same time. I think thats going to be tonights work.

[WVOtoGO]

Originally Posted by benhogan

No. You can have a bad master cylinder or slave cylinder even without losing fluid.

This happens when the piston seal is bad and the fluid simply goes around the piston. No fluid is lost. There is good pedal 'feel' but not much work is happening because the brake fluid simply moves around.

I suggest replacing both the master and slave together. If you only do one, the new one will make the old one bad. Replace them both.

I think this will solve your problem. Doing this is easy enough for a toyota truck.

And for a fraction of the cost, you can buy the rebuild kits and do them yourself with little effort, in no time at all. Why buy the whole thing, when it's the seals that go bad?

- Shelby

[SirNik84]

Originally Posted by Mike D

Ehhh?

lol should read gross don't ask me how that type-o came out... maybe it was all that beer i consumed yesterday at my friends wedding... yeah, i'm gonna blame it on that.

[rscurtis]

I would vote for a worn out pilot bearing. The hydraulic operation of the clutch has no bearing on whether the transmission stays in gear. It may make shifting difficult, but once in gear, it should stay in gear. Popping out of gear is usually caused by bearing play where there shouldn't be any.

[SirNik84]

Originally Posted by rscurtis

I would vote for a worn out pilot bearing. The hydraulic operation of the clutch has no bearing on whether the transmission stays in gear. It may make shifting difficult, but once in gear, it should stay in gear. Popping out of gear is usually caused by bearing play where there shouldn't be any.

This and the fact that 1,2 & 5 have no problems at all is what makes me question if the hydraulics are only cause to this problem... maybe we're dealing with 2 problems here.

[4x4_Welder]

It probably has a bent shift rail or worn shift fork. My 94 Toyota 2wd had the same issue with 1&2 due to me beating the ever living snot out of it.

[mpolli]

So he should take back the tranny under the warranty and get a 3rd one? Or maybe disassemble the first one and do a post-mortem.

[SirNik84]

My dad suggested talking to the junkyard and telling them I want a new transmission, and trading in the old one, but tell them not to scrap it till i confirm the new on is good. if the 3rd transmission is junk, tell them I want both dead transmissions for the price of one good one. and then take them both apart and build Franken-transmission.