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96 Explorer eating 4R70W's

AWD96spoon

Well-Known Member
Joined
September 27, 2017
Messages
132
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37
City, State
Ardmore, ok
Year, Model & Trim Level
1996, Explorer AWD
I have a 1996 explorer with the 5.0 and 4r70w with bw4406 swap. I rebuilt the motor in it almost 3 years ago, and had a reputable transmission builder rebuild the trans as a precautionary measure as I was planning to use the explorer as a daily driver. After getting the transmission back from the builder, and installing it, it had an immediate failure due to a faulty part from the manufacturer is what I was told. Builder rebuilt it at no additional cost under warenty. Since then, it has been rebuilt 4 more times and never lasts more than a couple hundred miles, before beginning to slip and have major issues. I was convinced that the builder was just incompetent and couldn't find the issue and fix it. After the last failure, I got my money back from the builder and had AAMCO pick it up and put a remanufactured unit in it. About 150 miles after picking it up from AAMCO, I started having issues with my ABS light coming on, OD off light flashing, and check engine light coming on with code P0503. I got frustrated with the truck and it sat in the yard for for couple months before I replaced the VSS. I haven't driven it enough to see if it's fixed because when I took it for a test drive, I made it to the end of the block and the transmission didn't want to take off from the stop sign(same thing it did last time it had issues) so I drove it around the block and parked it. I parked it on the driveway after that and the next day noticed the pan was covered in ATF and there was a significant drip spot on the driveway. I figured that it had been leaking fluid after every rebuild since they kept using the same aftermarket pan and rubber style gasket on every rebuild and I always had the truck parked in the dirt so I never noticed the leak. Last night I went to replace the pan with the stock one and stock gasket, but when I pulled the pan out, it was full of fine metal dust and the drain plug magnet looked like a chia pet. There was not any chunks or large shaving, but the bottom of the pan was coated in this stuff. The transmission is still under warranty for another couple years, so my question is, do you guys think there is still an underlying issue with the truck that's causing it to kill transmissions, or do you think it was probably just leaking out enough of its fluid to kill itself every time? Should I just put it back together and hope it's not hurt too bad or take it in for a warranty claim? I have way too much time and money into this thing and I'm honestly sick to my stomach thinking about another transmission being bad. I need some help here.
 



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I dont think this is because of the low fluid, dont get me wrong low fluid will sure enough damage the transmission but this seems like this is something different.

It would be helpful to know what is failing inside the transmission, is it the same part failing over and over. Maybe you can call the shop that has been in it a few times and find out what keeps happening.

The VSS rarely fails with this transmission, I see this code mostly because the vehicle quits moving in gear and the computer sees no signal from the sensor or the sensor has enough metal stuck to it that it can function.

So find out what keeps failing inside the transmission and that can give me a clue on what might be happening
 






I dont think this is because of the low fluid, dont get me wrong low fluid will sure enough damage the transmission but this seems like this is something different.

It would be helpful to know what is failing inside the transmission, is it the same part failing over and over. Maybe you can call the shop that has been in it a few times and find out what keeps happening.

The VSS rarely fails with this transmission, I see this code mostly because the vehicle quits moving in gear and the computer sees no signal from the sensor or the sensor has enough metal stuck to it that it can function.

So find out what keeps failing inside the transmission and that can give me a clue on what might be happening
I was told that the clutches were burned up the first time because my filter fell off and was allowing it to suck up air, the second time was told it was a wore Pressure regulator bore that caused it to burn up the clutches, 3rd time was told the torentien bearing came apart and chewed up the lower planetary, 4th time was told the lower planetary was chewed up again and trashed the pump.
 






Sounds funny something not right
 






Sounds funny something not right
I agree. That's why this last time I went with a totally different core, and shop, but stillbhaving issues.
 






A few things that stick out, first these filters are not known to just fall out especially new ones and the pan holds them in place. It should have been falling out of gear and delayed engagements prior to any failures of the clutches if this was the case.

The PR valve is a known wear spot and does cause driveablity problems but not known to burn the clutches much especially in such a short period of time.

The thrust bearings and planetary are known to fail but not so soon after rebuild, either the builder missed a bad bearing or installed it incorrectly or the output shaft is being forced forward. We see this on the E series vans they get overloaded and the drive shaft will bottom out and shoves the output shaft forward and busts the thrust bearings and the entire planetary set including the direct drum will fail. Yours being a 4x4 I wouldn't expect this but you may want to make sure when the T case is bolted up something isn't causing the output shaft to be preloaded.

If the planet and bearing have failed due to being overheated make sure you check cooler flow back to the transmission from the coolers, no cooler flow will destroy the gear train, its easy to spot because it will look like its been hot and black.

The pump rarely fails, I don't think I have put a pump in one of these in years even with heavy gear train failures, so that is unusual. If the failure of the pump was due to the pump gear wearing into the pump stator the first this I would be looking for is excessive crank shaft end play. Also if the converter is making metal this will damage the pump. Make sure both the engine dowel pins are there a miss alignment here will destroy the pump in a short period of time.

Hope this will shed some light on what might be going on.

- Crank shaft end play
- Engine dowel pins
- Output shaft preloaded
- Cooler flow
 






Ditto. There are a ton of parts which can have issues, but given a solid core trans, no install issues like preloaded shafts etc, proper build, cleaning etc, all needed parts replaced, and clean cooler lines etc, the 4R is a great trans. So I would expect something among all of that was not right, in every failure.

I'd ask them what parts they changed and what they didn't. Nothing should have been skipped among solenoids and accumulators, the TC should be a high quality replacement of course, and there better be an external filter in the cooler line, to protect the transmission from prior debris.

I would have several things done inside the VB, which most shops never do. I like to upgrade to everything Sonnax has for the VB, which are several and aside from the newest item a few years ago, cost maybe $100 total. That new item supersedes one of the other still available items, which is in their Zip kit. That's a $75 upgrade, a ...boost valve kit, and the one they have for the same bore is not to be used with it(other one is about a $25 item).

Most problems are related to VB function, except for the obvious install issues mentioned(including the clean cooler system). Do the basics, install properly, use a decent core(not ever burned up before or high mileage), upgrade the VB well, and the 4R should last for ages.

There are a few other hard part upgrades, but not necessary for any mild applications. A shift kit can help too, but the Sonnax VB parts are about equally as good for a rebuild. I'll be trying the J'Mod thing the next time I work on my 98's, that should be a very good improvement for all 4R's.
 






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