Fishin_XJ

Starting from the top. I replaced the trans with a used one that a guy had sitting in his garage for a year or two. The install went flawlessly, couldn't have been any easier. I told to worry about what I do and I looked over everything multiple times, everything has been reinstalled and connected the way it came out. (I even replaced missing bolts from before I got it) Today I started the jeep for the first time since I got it together, started great, but when I place the trans in reverse or drive the only thing that happens is the rpms rise to just over 1000. This has been a huge letdown since everything went together so well. I went over EVERYTHING again and found nothing out of place even the tcase was in gear. The only Idea i would have is that the pump might have lost prime if that's possible. And yes the dipstick reads full idling in neutral and park. If it is possible for the pump to lose prime how do I go about priming it?

Chick-N-Picker

I am not expert at all. But will it move if you unplug or take the fuse out of the TCU control unit up and under the passenger side dash? That may at least help you know if it's mechanical or electrical. Just an idea.

You can take out this fuse or go for a full unplug of the TCU. Might be a good idea to spray those connectors anyway. [Click to enlarge if you need]

awg

If you have an AW4 (or whatever trans), I suggest you free download the FSM and peruse the relevant Chapter on Auto trans

I think the AW4 engages Reverse with a manual action, so if that doesnt work, and no other gear position works, try jack rear wheels and see if they turn

The above would usually mean some internal part of the trans has failed, not a solenoid, there may have been a reason it was sitting on a garage floor

My AW4 lost power, so I replaced it with a used one, luckily it is still working, but did leak out the front oil seal at first, so I got to do the job twice, sounds like you will

Fishin_XJ

the trans came out of a 95 Cherokee that was in a rollover accident during to loss of control. And was still driving afterwards. I didnt know if the pump needed to be primed by back flushing or what could have happened

awg

you could try hook a pressure gauge to the port and see what it says

torque convertors, pumps and valve bodies all have to fill with fluid but i cant see why the pump would not self prime, its just 2 gears in a housing

what happens when you jack rear and go thru gears ?

make sure the range cable is operating as it should

lawsoncl

I agree, it's not an electronic problem if reverse isn't working. Testing pressure is a good place to start if you have a gauge - I think that pressure test port is metric?

T/C was fully seated before mating up to the block? Bolted back to the flexplate? Throttle body to trans cable is hooked up and adjusted? Even if the xfer case wasn't working, you'd still feel it upshifting in drive. Can you push the vehicle, and the park pin isn't somehow stuck?

Fishin_XJ

I am 100% sure the cable is connected correctly. With the jeep running and the trans hoses disconnected I can place my finger over the end and no pressure or suction is there on either hose. And I asked the guy how long it sat and with what he said and the time I've had it it's been 5 months since it was running and driving. I'm currently questioning whether or not I should use the pump out of the old trans since the only issue it had was no 3rd or 4th gear. But still ran and drove otherwise.

Fishin_XJ

I should also mention that when shifting and pausing at each gear there is no weird or unusual noises coming from the trans.

Jeepwalker

Just asking the obvious question, is the fluid level where it should be? Did you use the torque converter from the 'new' tranny, or your old one? Sorry if you already mentioned these questions....

I've changed a lot of tranny's usually used ones, often that sat a long time. I've never had one that didn't have 'prime'. What you could do is remove the feed hose from the tranny (at the radiator), and port into a 'clean' 5gal bucket with a piece of clear vinyl tubing. Have a helper start the vehicle while you observe the fluid flow. It should come out real fast and strong (so have a helper start/stop the vehicle).

lawsoncl

nm.

Fishin_XJ

I've had a helper start and stop the engine with the lines off and I have no fluid coming out of either hose or suction. The fluid level stayed a bit higher than operating level on purpose to try getting it to the pickup and it still didnt provide pressure on the hoses. I was told by a retired trans mechanic that sometimes after a rollover depending on how long the motor ran upside down the trans pump can go bad. I also asked what I'd be be out if I was to swap the pumps from the old trans and the "new" one. And was told time and labor. So with that being the cheapest option I'm gonna attempt my hand at swapping the pumps and see where that gets me

awg

On the pre 98 trans there is a T55 Torx that can be removed to allow fitment of 2 vital things..a trans pressure gauge, and afterward, a trans temp gauge

I am 99% sure the female hole in trans is is M14 x 1.5, but double check the archives

It is the same as the trans cooler lines, which I have fitted M14 x 1.5 x 3/8" barb as I had trouble with the push in cooler fittings

Toyota versions often have a trans temp gauge

there are some good AW4 rebuild Youtubes