87 AW4 1 st gear is slipping bad now

Old story, update.....

At first it only acted up on cold mornings, first run of the day, last 3 winters, over about a 30,000 mile, 3 year period. Once the T fluid warmed up it would finally engage 1st gear and drive. Reverse has always worked, still does, so it is not the torque converter IMHO. I have given it 2.5 quart Dex III transfusions 2-3 times a year the last 24 months, and 2, 1/2 pint treatments of Trans X each winter, all which helped the last 2 winters. I added 1/2 quart of transX 4 weeks ago as the fluid was a 1/2-1 quart low.

Then this week I added 3/4ths of a quart of Dexron III, and got it to the middle to low end of the hatch marks cold. Fluid looks and smells fine. But the last addition of Dexron III did not get it the 1st gear engagement working again like normal. Even after a good warm up, it now wants to slip badly, and slips with some noise (new noise, mild noise, but definatly not a normal noise), so I am trying to decide what to do next.

Not sure a series of transfusions of Dexron III fluid will do the trick anymore (like they did in the past), as the cold temp that causes problems has reached about 75 F this time, versus say 60 F, and 45 F two winters ago. And this week, it did not want to work even at 80 F. Seems to have a small leak developing too, but not sure the extra dose of TransX did not cause part of the lost volume, as it has a very thin viscosity, solvent like. It is supposed to help swell old seals and help them seal, and help clean up, dissolve varnish that can make the valve body valves stick.

I don't think there is any reason to suspect the solenoid, as I have not heard of them being temperature sensitive and weak...., and the Tranny computer is ruled out too, mostly because they have worked fine while this progressive cold start up winter issue has gotten slowly worse over 3 winters now. This winter the problem started at 75 F, not 45 F.

3 years ago someone here suggested the valve body might need new o'rings and seats/seals.

I have a lot of choices, including a spare 87-89 tranny that was working when pulled, sitting in my shop. It has been in my storage for 3-4 years now (so it might need new seals from lack of use?). But I don't have a lot of spare time. Lastly I don't trust others to work on my junk anymore, and don't know anyone I trust really. But if there was someone others have used in the South East Houston area that really knows AW-4s that would work with me, I might consider using them. Otherwise, I need the fastest simplest route, and I don't need to be swapping the tranny five times, as I am "Getting too old for this Sh*t"!

I don't mind spending some money on say a new valve body, to install in the current AW4 if that might solve the problem. I guess I need to pull the pan next and see what if anything is in the pan, to see if the clutch plates are OK or not. I know there was some kind of work done (flex plate, Tranny...) before I bought the jeep, but I don't know how much they really did to the AW4, if any. It had 224,000 miles when I bought it in 2004-05. Now has 278,000 miles.

I have the AW4 manual.

So, looking for some expert guidance, ideas from those who have rebuilt AW4s, in part or completely, or found easier fixes for this problem. One person suggested recently that I try Lucas tranny additive, the thick stuff made specifically for slipping transmissions. He said it worked for him for a long time on the company 1996 XJ at work, and is still working!

I can't help but think that maybe the extra TransX may have dissolved some varnish, then dried up again and left the varnish in a worse spot since I did not drain and flush it! I am wondering about running some transX in neutral for 30 minutes, then do a few transfusions (say 5 quarts) with Dextron III to dilute and remove the varnish and transX, then try the Lucas last, before moving onto real hardware replacement if needed.

Well, I would at least test the solenoid. Solenoids, like any other electrical device with moving components can get weak before they fail.

That said, pulling the valve body and cleaning it up/new o-rings and seals would likely be in order.

The sound could simply be the clutches/brakes not fully functioning due to low pressure.

Low pressure due to old worn seals that sealed when they got hot was suggested once before, many moons ago. The slow three year, decline, and winter / summer cycle where it worked perfectly all summer seems to back up theory now. Dying Dextron II-III fluid seemed to contribute.

I wonder how hard it is to pull and rebuild the AW4 valve body? Does any one have an online source for a kit for the valve body, cheap?

I suspect I could do a valve body R&R, and rebuild with out too much trouble, if I had a kit....

Do really think a solenoid could cause this cold weather cyclic decline issue over three years? I never say never, but? Not even sure how I would test the solenoid for that problem?

I assume you've tried the trick of disconnecting the TCU and manually shifting. If it were me, and I had a spare trans sitting there, I'd probably just swap it out.

Try getting ohm readings cold, then hot, see if there is a significant difference.

rockauto.com has the overhaul kit for $68, check the photo, looks like it has more than what you need.

The Master overhaul kit is $221, includes friction disks, etc.

You might get the parts and pieces cheaper at the Jeep dealer or even from Toyota.

Instead of messing with the valve body, which isn't likely to get you anywhere, I'd just slap a different transmission in it and move on with life. Much easier in the long run.

Unless you think it is fun to rebuild trannies, the most practical thing would be to swap with a low mileage tranny. You should be able to get one with 100k or less on it for $200. Seems like you have babied this one long enough.

lawsoncl said:

I assume you've tried the trick of disconnecting the TCU and manually shifting. If it were me, and I had a spare trans sitting there, I'd probably just swap it out.

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Have not tried that yet, but it does the same thing, slips badly in 1-2, 3 and D (never gets up to speed, tops out at maybe 10 mph @3000 rpm, and reverse works perfectly. So I did not see the point in disconnecting the T computer.

Try disconnecting the TCU (if I'm understanding correctly and you haven't.) Starting out in overdrive with the torque converter unlocked feels a lot like 1st slipping.

And yes, the cheapest fastest route is probably slapping a new tranny in it. If you weren't so far away I would have one to donate to the cause, it's been sitting in my storage unit for over a year now, was given to me for free by a good friend of mine when he heard mine was starting to slip. 21 spline, came out of a 90 iirc, free, if you want me to ship it to you, you pay shipping and it is yours. I believe it needs a new input seal, comes with a torque converter.

joe_peters said:

Try getting ohm readings cold, then hot, see if there is a significant difference.

rockauto.com has the overhaul kit for $68, check the photo, looks like it has more than what you need.

The Master overhaul kit is $221, includes friction disks, etc.

You might get the parts and pieces cheaper at the Jeep dealer or even from Toyota.

Click to expand...

Thanks. I got the pan off today. Drained it after a good warm up run with extra TransX added first.

Filter screen, is actually about 300 mesh very fine stainless steel wire mesh screen (cloth) filter, which contrary to what I have read here many times before, could plug up!!!! Mine was dirty, possibly dirty enough to starve the pump!!! Pan had some black goo in the bottom, looked like moly grease, fluid was very dirty, but not burned, the black stuff was also on the filter screen.

There was no clutch material and no metal powder or metal flack or metal bits or pieces of metal in the pan at all!!!! I was a bit surprised. The valve body, tranny internals were spotless!!!! Never seen one that clean.

Middle filter mounting bolt was completely missing!

Bottom drain pan bolts were loose.

I found a VERY loose bolt on the side that appears to hold the throttle cable connection to the side of the tranny valve body, so that linkage was no longer completely tied down at the tranny attachment point.

I will check the solenoids tomorrow. Ran out of time and daylight today.

kastein said:

Try disconnecting the TCU (if I'm understanding correctly and you haven't.) Starting out in overdrive with the torque converter unlocked feels a lot like 1st slipping.

And yes, the cheapest fastest route is probably slapping a new tranny in it. If you weren't so far away I would have one to donate to the cause, it's been sitting in my storage unit for over a year now, was given to me for free by a good friend of mine when he heard mine was starting to slip. 21 spline, came out of a 90 iirc, free, if you want me to ship it to you, you pay shipping and it is yours. I believe it needs a new input seal, comes with a torque converter.

Click to expand...

Thanks, I already have an 87 and 94 spare. I don't know if my 87 spare was 2wd or 4wd, might half to swap the tail cone if the spare is off of a 2wd. I just don't like the idea of doing all the work of a swap, with out doing some testing, and possible minor R&R (new seals and o'rings at least) on it before I do the swap. The only thing that is not nearly new on the 87 now is the tranny, engine, and body. The body is still great. I plan on keeping it for very long time. It was a daily driver most of the last 2 years now (even with 278,000 miles on it). So it is temping to take the spare I have, do a complete rebuild on it and swap the two out. But I am naturally lazy (for a do it your self-er that is, LOL), if it is a simple easy fix for now without pulling the tranny, that is the path I will choose.

I thinking it is running in overdrive, like you mentioned. So solenoid #1 is suspect, as well as parts in the valve body IIRC. I need to re-read the manual again.

Ecomike is on an AW4 mission!

Keep us posted on how it goes........

Ook, sounds good :thumbup:

Ps, if you try and use a 2wd aw4 you will have to completely disassemble it, swap output shafts, and reassemble. The tailshaft is different since the 2wd is longer, and has 27 splines to match the driveshaft slip yoke, while the 4wd is shorter and has (in this case) 21 splines.

I have plans to rebuild my old 2wd 91 aw4 as a known good spare 4wd aw4 for the mj eventually, that is, if I don't swap in an ax15.

Ecomike said:

Have not tried that yet, but it does the same thing, slips badly in 1-2, 3 and D (never gets up to speed, tops out at maybe 10 mph @3000 rpm, and reverse works perfectly. So I did not see the point in disconnecting the T computer.

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The pump pressure is at its maximum in reverse. This confirms my suspicions of old hard seals even more.

Which old hard seals? Where are they exactly?

Just dawned on me that if the filter screen was starving the pump in forward, it would probably starve the pump in reverse?

Hmm, sounds like I need to pray for a bad solenoid, or wire/ground on the solenoid.

kastein said:

Ook, sounds good :thumbup:

Ps, if you try and use a 2wd aw4 you will have to completely disassemble it, swap output shafts, and reassemble. The tailshaft is different since the 2wd is longer, and has 27 splines to match the driveshaft slip yoke, while the 4wd is shorter and has (in this case) 21 splines.

I have plans to rebuild my old 2wd 91 aw4 as a known good spare 4wd aw4 for the mj eventually, that is, if I don't swap in an ax15.

Click to expand...

I got the impression a while back that it was a lot simpler than that? Completely disassemble? How completely?

Guess I need to look at what I actually have here in the 87 for a spare, 2WD or 4 WD.

Unfortunately the tailshaft is about the first thing that goes in... everything else gets stacked on top of it. Wish it wasn't the case, my MJ would already be 4wd by now.

kastein said:

Unfortunately the tailshaft is about the first thing that goes in... everything else gets stacked on top of it. Wish it wasn't the case, my MJ would already be 4wd by now.

Click to expand...

I guess I am thinking of the tail piece that is easy to R&R and replace the bushing/seal in, and not the tailshaft itself. I have yet to really get into AW4 internals work, mostly just read the manual several times, troubleshooting the TPS,tranny computer, wiring, dirty fluid....and so on.

I will get back with you in a few days.... I might be interested in that spare tranny after all. I do have 94 4wd tranny, AW$ still tied to the 94 transfer case, but IIRC there are other swap issues there too. Still hoping it is something simple like bad fluid or wire or solenoid, as the bottom of the pan was clean except for for the greasy black stuff, maybe varnish the TransX removed.

A 94 should bolt up fine, except you may have to splice a different connector on to make it plug into the harness, and possibly swap the TV cable (not sure it clips to the throttle body the same way on RENIX setups.) The speed sensor is 100% compatible 87-97 on AW4s. 84-95 transfer cases have the same rear output housing setup so you are fine on that front as well.

Let me know at any point if you want it, I am tired of tripping over the stupid thing!

Ecomike said:

Which old hard seals? Where are they exactly?

Just dawned on me that if the filter screen was starving the pump in forward, it would probably starve the pump in reverse?

Hmm, sounds like I need to pray for a bad solenoid, or wire/ground on the solenoid.

Click to expand...

bonded seals on the pistons. I just replaced a focus auto tranny for the same reason. PUmp was working properly, but the seal bores were gouged and the pressure was leaking past, therefore not actuating the hydraulic servos that pus hthe bands.