A4LD shifting issues

[Kaidenshi]

Hi folks. I know the A4LD and its many issues and quirks has been covered to death in this community; I've read all of the posts that I think are relevant, but I haven't found a solution to my issue yet. I was hoping to get some insight.

So the 1994 EB 4x4 I posted about a few weeks ago has turned out to have a transmission issue. A few days after I got it, I noticed it was being sloppy in all the gears, hunting back and forth like the kickdown wasn't set right. I had already planned a full round of fluid and filter changes, including the transmission, so I went ahead and changed the fluid and filter and adjusted the bands, as well as the kickdown cable. I followed all the suggestions on this site and in the technical manual for the A4LD. After the above changes, I now had excellent, almost like-new performance in 2nd through OD, hot or cold. It was like a new truck. Except...when cold, 1st to 2nd was great and in line with the rest. Once I'd gone just a few miles, it would end up needing high revs (3500-4000rpm) to change into 2nd. From there, excellent performance in regular driving, but stop and go traffic was a pain due to the long 1st gear.

So this past weekend, I figured it wouldn't hurt to change the modulator valve since I'd be doing round two of fluid changes (engine oil and filter, transfer case, diffs) and I'd be under there anyway. After going to the trouble of taking off the cat, I removed the old modulator valve and found it was actually fairly new. Interestingly, the pin/rod was missing. I found the pin a few minutes later embedded in a layer of grease on the topside of the tranny, so I cleaned off the pin, put it in my new modulator (a twin to the one I took out, with the hex adjustment screw), reconnected vacuum, and put everything back together.

This time around, I only had 2nd gear. No 1st, and no upshifting from 2nd. I got back home and swapped back to the old modulator, again with the pin inserted correctly, and same thing. I put the new one back in and adjusted it a couple of turns CCW, and now I have shifting through all gears but only at very high revs (4000+). It shifts really, really hard too.

I'm at a loss; if the old modulator was missing its pin it shouldn't have been able to shift out of first, correct? And by putting in a new modulator with the pin correctly inserted, I should have 1st-2nd? And either way, swapping a modulator should have had no effect on 2nd-3rd and 3rd-OD, right? Fluid levels are good, I rechecked my band adjustments and they were correct. When I did the fluid and filter change, it looked like a new transmission on the inside; valve body was clean, magnet had very little material on it and what was there was very "silt" like, no chunks or pieces of metal.

One thing I've noticed that threw me off is what appears to be a 3/16" or 1/4" vacuum port on the extension housing, with no hose on it. It's coated in grime and appears to have been that way for years. I have no idea what that would connect to; does the governor require vacuum? If so, I have a spare port on the tree coming off the manifold that's currently plugged, could I use that to connect it? I have tried looking at photos of the A4LD and its extension housing online and I can't tell if that port serves any actual purpose.

Thanks for taking the time to read through all of that. I know it's a lot of info but I like to be thorough when trying to diagnose an issue. Worst case, I have a local transmission guy who comes highly recommended; I spoke with him about it and he thinks it's the wrong kind of modulator but without looking at the truck he is stumped on the sudden high gear issues. I can take it to him if necessary but I'd rather fix it myself if I can.

 

[MrQ]

I wonder... do you have the auxiliary trans cooler? Those are known to get clogged and restrict fluid flow to the transmission which can cause delayed shifts as well as burn up the transmission due to a lack of fluid.

BTW, all the modulators I found worked from 92-94, Ford tended to use the same part for a lot of vehicles.

 

[Kaidenshi]

I wonder... do you have the auxiliary trans cooler? Those are known to get clogged and restrict fluid flow to the transmission which can cause delayed shifts as well as burn up the transmission due to a lack of fluid.

It has what I believe to be the factory transmission cooler, mounted at the radiator and with metal lines running to the transmission. I haven't thought about that, but I did notice the transmission body was too hot to touch after less than a mile of driving, and the fluid is already getting a bit dark even though it has less than 100 miles on it since I changed it. It just seems weird that it suddenly had issues after changing the modulator and replacing the pin (which was missing when it was working fine in high gears). It definitely could be a fluid issue!

 

[MrQ]

Probably when you started messing with the bands and changing the fluid it accelerated the creation of the blockage as the detergents in the ATF cleaned the transmission. Did you use Mercon V?

I also strongly suggest you do not continue to drive it until this problem is solved. You could burn up the bands in the transmission very quickly especially if you are shifting at 4k rpm!

Also are you sure the tube you saw was not on the transfer case or on the transmission itself? If so those are breather/vent tubes. The transmission should have one that looks like a "U" that lays on top of the transmission with one side connected by a short rubber tube to the vent port. The T-case vent tube is just a rubber hose which may have been left off if the transmission has ever been pulled.

 

[Kaidenshi]

I did use Mercon V for the fluid change, and a Wix filter. It's not my daily driver so it's basically parked until I get this worked out. I've put less than 200 miles on it since I got it, and almost none since this weekend when all the above happened; just down the road and back testing my adjustments.

So do you suggest flushing out the cooler as my next step? I'm thinking of doing that this week as we are going on vacation next week and if I didn't fix it by Friday I was going to just drive it to the transmission guy on Saturday and let him have a go at it. Now that I think it may be a fluid/heat issue, I'm loath to drive it the 20 miles to his shop and risk internal damage without addressing that first.

 

[Kaidenshi]

Also are you sure the tube you saw was not on the transfer case or on the transmission itself? If so those are breather/vent tubes. The transmission should have one that looks like a "U" that lays on top of the transmission with one side connected by a short rubber tube to the vent port. The T-case vent tube is just a rubber hose which may have been left off if the transmission has ever been pulled.

You know, it could have been on the t-case. I was looking down from the access panel in the floorboard when I saw that, and at that angle it could have been further back than I thought. I know my old Bronco II had a vent tube for the t-case, and it was the manual shift version of the same case.

 

[MrQ]

I did use Mercon V for the fluid change, and a Wix filter. It's not my daily driver so it's basically parked until I get this worked out. I've put less than 200 miles on it since I got it, and almost none since this weekend when all the above happened; just down the road and back testing my adjustments.

So do you suggest flushing out the cooler as my next step? I'm thinking of doing that this week as we are going on vacation next week and if I didn't fix it by Friday I was going to just drive it to the transmission guy on Saturday and let him have a go at it. Now that I think it may be a fluid/heat issue, I'm loath to drive it the 20 miles to his shop and risk internal damage without addressing that first.

Just replace it altogether. Not worth re-using the old one if the problem will just return.

 

[BrooklynBay]

The A4LD had two different types of valve body gaskets. The regular gaskets were very thin. Loose valve body bolts over time could cause those gaskets to peel in various locations. There are slightly thicker gaskets as a upgrade. You should look into removing the valve body, clean it up, lubricate it, replace the upper & lower gaskets, and tighten the bolts with a 1/4" drive In/LB torque wrench.

 

[Kaidenshi]

Just replace it altogether. Not worth re-using the old one if the problem will just return.

I found a "Class V" (whatever that means; matched to the hitch size?) plate style aftermarket cooler on etrailer.com for under $100, would I be able to use it and just bypass the factory cooler? I can't seem to find the factory unit without scrounging junkyards.

https://www.etrailer.com/Transmission-Coolers/Ford/Explorer/1994/D13614.html?VehicleID=19941827431

 

[Kaidenshi]

The A4LD had two different types of valve body gaskets. The regular gaskets were very thin. Loose valve body bolts over time could cause those gaskets to peel in various locations. There are slightly thicker gaskets as a upgrade. You should look into removing the valve body, clean it up, lubricate it, replace the upper & lower gaskets, and tighten the bolts with a 1/4" drive In/LB torque wrench.

I'll look at doing that as well. A gasket set is super cheap even for the upgraded version. My wife is of the mind to just get it to the transmission guy and let him do all the work (she's tired of me wasting weekends on car work even though it's my favorite hobby). She wants it ready for camping by April.

I've also considered swapping in a M5OD since I prefer manual anyway, but I still like the idea of keeping the truck as stock as possible. If it needs a new A4LD or a rebuild though, I'll seriously consider a swap to manual just to simplify things and future-proof it.

 

[BrooklynBay]

You could find a shop on WWW.ATRA.Com.

 

[Kaidenshi]

You could find a shop on WWW.ATRA.Com.

Thanks for the link! Looks like the guy I was talking to is not on their directory but there is a shop a bit closer that is. I'll give them a call.

 

[Kaidenshi]

Checked out the shop I found on ATRA and it was a good choice, turns out their master builder is a bit of a celebrity among transmission specialists around the country. Took the truck to them and spoke with him for a while, and I have a feeling he will have me up and running by the weekend. He's thinking it's just a sticking governor after driving it but he won't know until he looks at it later today. Interestingly, when I told him I had done the band adjustment at 2.0 turns on both bands, he said it should actually be 1.5 turns, and that could have contributed to the issue. I also mentioned that it could be a clogged cooler and he said they always check that out as part of diagnostics. Feeling optimistic right now. Thanks again guys, and I'll update once I hear back from them.