Auto trans gurus

justjeepin86

justjeepin86

Well-Known Member
Joined
Jul 9, 2005
Location
Winston-Salem, NC
I'm ready to try to move this Jeep now. Problem is that the trans stays locked up. It's a mid 80's 700r4 that was driven in the shop to replace with a manual. Known good working trans. TCI converter. I installed a new adjustable kick down cable and adjusted it per instructions. Fluid is at the right level. Lock up switch on the side is wired right and has vacuum. What could be causing it to not unlock? It has been sitting for a few years, but inside a shop.

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From what I remember, their natural state of being is locked. The fluid pressure unlocks them. So, if I remembered that right...it sounds like the lockup solenoid is stuck and not letting fluid get in the converter to unlock it. That or there's an issue with that vacuum switch.

I would probably get a lockup setup that doesn't use vacuum. It'll just use a 12v source, a ground, and a wire to the brake switch.

If you wind up needing it, I actually have a lockup setup from Bowtie Overdrives that was leftover from the 700R4 I had in my CUCV many moons ago. Just let me know.
 
The valve (not solenoid) could also be stuck. Seen that a couple times. It is accessible with the pan off. A small piece of debri or aluminum burr can hold that valve open and keep it locked up.
 
Croatan_Kid said:
From what I remember, their natural state of being is locked. The fluid pressure unlocks them. So, if I remembered that right...it sounds like the lockup solenoid is stuck and not letting fluid get in the converter to unlock it. That or there's an issue with that vacuum switch.

I would probably get a lockup setup that doesn't use vacuum. It'll just use a 12v source, a ground, and a wire to the brake switch.

If you wind up needing it, I actually have a lockup setup from Bowtie Overdrives that was leftover from the 700R4 I had in my CUCV many moons ago. Just let me know.
Click to expand...
Just spoke with a guy
at my local reputable transmission shop. He said that the trans should be unlocked in it's normal state. I had a pretty long conversation with him.

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Last edited:
Maybe I was thinking about air brakes....
 
justjeepin86 said:
Just spoke with a guy
at my local reputable transmission shop. He said that the trans should be unlocked in it's normal state. I had a pretty long conversation with him.

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Click to expand...

This is correct

Croatan_Kid said:
Maybe I was thinking about air brakes....
Click to expand...

This is for the most part correct at least for most trucks and trailers. Dual cannisters will have a park or Maxi brake that is in a naturally locked state and requires air pressure to release.

As far as the trans lock up, you may have been thinking of the state of the lock up solenoid itself. Naturally with no power to it I believe it allows fluid flow through its orifice and for lockup when power is applied it stops flow.
 
NC-V said:
This is correct



This is for the most part correct at least for most trucks and trailers. Dual cannisters will have a park or Maxi brake that is in a naturally locked state and requires air pressure to release.

As far as the trans lock up, you may have been thinking of the state of the lock up solenoid itself. Naturally with no power to it I believe it allows fluid flow through its orifice and for lockup when power is applied it stops flow.
Click to expand...
What are the chances is the lock up solenoid being clogged and causing my problem?

Also, I was thinking. Would be running the motor with the trans 3 quarts low on fluid, hurt it? I didn't ever try to shift it, just ran the engine.

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justjeepin86 said:
What are the chances is the lock up solenoid being clogged and causing my problem?

Also, I was thinking. Would be running the motor with the trans 3 quarts low on fluid, hurt it? I didn't ever try to shift it, just ran the engine.

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Click to expand...

It is possible it could clog, but I do not specialize in transmissions, just my personal experiences. It is very easy to drop the pan and test the solenoid. You can jumper or power probe it while blowing through it.

I can't see how running 3 quarts low would make it stay locked. You basically have only 3 options. The solenoid, the valve in the pump body or the converter itself.
 
If it overheated the converter, I guess it could fuse the clutch to the Shell/hub. Some transmissions are pressure to release, just not the 700r4. Stuck valve might do it, but I'd be more suspicious of a clutch pack fused together.
 
Hell, I built a 700R4 for my CUCV several years ago and shortly after installing it, it wouldn't shift out of third. I took it back out, tore it down, anddidn't find anything. So, I put it back together and back in the truck...go figure, it worked fine after that.
 
Croatan_Kid said:
Hell, I built a 700R4 for my CUCV several years ago and shortly after installing it, it wouldn't shift out of third. I took it back out, tore it down, anddidn't find anything. So, I put it back together and back in the truck...go figure, it worked fine after that.
Click to expand...
There is a good chance that I would try to do it myself. The only reason I don't want to, is not knowing what to look for to tell what's good and bad.

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beginning to feel shittier about this by the day... Bishop and I were tearing up the beaches in this thing, miles before I pulled it.
 
Chuckman said:
beginning to feel shittier about this by the day... Bishop and I were tearing up the beaches in this thing, miles before I pulled it.
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Ah, no worries! It's all good. The last thing on my mind is that you passed a problem to me.

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justjeepin86 said:
Because the Jeep won't stop without choking out. It's working like a manual. Drags the front tires when in reverse

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Click to expand...
So neutral is neutral, reverse is reverse, drive is drive ...

Found this on a search.. "the engine is stalled (killed) when the trans is shifted to any gear. This tells me the trans pump has been modified for non lock up operation. That explains the first converter never locking up.. and the converter was modified for non lock up operation. Pump and converter must match, if one is modified, the other needs to be. When a pump is modified for Non lockup, the oil flow direction into the converter is changed. So , now when you start the engine the converter clutch is applied."

Just read the first post, so I don't think the above is the case.

700r4 will not lock in 1 & R normally.. possibility if the tcc apply valve isn't stuck.

Double check the kick down cable adjustment, can affect it also
 
a_kelley said:
So neutral is neutral, reverse is reverse, drive is drive ...

Found this on a search.. "the engine is stalled (killed) when the trans is shifted to any gear. This tells me the trans pump has been modified for non lock up operation. That explains the first converter never locking up.. and the converter was modified for non lock up operation. Pump and converter must match, if one is modified, the other needs to be. When a pump is modified for Non lockup, the oil flow direction into the converter is changed. So , now when you start the engine the converter clutch is applied."

Just read the first post, so I don't think the above is the case.

700r4 will not lock in 1 & R normally.. possibility if the tcc apply valve isn't stuck.

Double check the kick down cable adjustment, can affect it also
Click to expand...
Yeah, I read that before.

So, you are saying that the tcc apply valve could be stuck or the kick down cable could be wrong, if I read that correctly? I'll check the kick down cable again. Don't have much time at the moment though. Just started moving.

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Correct. Also check the solenoid to see if it's clogged. Should click with 12v applied and seal. If that and the kickdown adjustment are good, then it's probably the converter since it's got all gears. But since I re read the original post, I see you changed the kick down cable, one of the things that changed since it was pulled, so I'd start with that.
 
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