4r70w has little fluid flow to cooler

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May 31, 2024
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I drove a donor 1997 ford explorer into my shop and used an and advance adapter 50-2704a conversion kit to mate the awd 4r70w up to the dana 20 transfer case. All locks when engaged to the driveshafts. I used the original computer and required the harness, etc. engine seems to run as expected.

Here’s the issue. I have no movement in any gear. Little to no fluid flow to the cooler. When I put it in gear, the rpm’s go up 2-300 rpm’s for a given period and settle (I would typically except it to bog down because of a load to move).
What I did initially to check was I took the pan off to see if the new filter had fallen out. It was in place, and I did get the old o ring out and install the new one. I took the trans back out to check to see if the TC was fully seated and to inspect the pump for any damage, cracks, or leaking. All was perfect but I didn’t remove it and look beyond the surface. All I’ve done to the transmission outside of the conversion kit (didn’t disassemble the trans) is drain the trans (not the tc) and put in the new filter. I do remember defaulting to manual transmission ways and I filled initially through the line port and not tho dipstick tube. I am used to manual transmissions and automatics are somewhat foreign. However, when I checked the pan, I did get all the fluid out. So I don’t think that caused any issue.

I am trying to figure out why I have no fluid flow to the trans cooler. Everyone I’ve talked to has said that it has to be the pump because it’s mechanical. I was thinking at first it could be a valve body/solenoid issue of some kind, but am unsure as I don’t know automatics. I began taking things back apart but stopped and thought I would ask here and perhaps Clinebarger or someone with more knowledge here can provide some insight. The rpm increase and no movement has me puzzled even though I understand if there’s no flow… there can’t be movement. Just as a side note, everything went in well, there was no whines, grinding, or noises abnormal when running, and I’ve seen no shavings at all in what fluid has come out.
 
Dumb question, on the coolers lines do you have a thermostatic bypass valve? I don't remember a 4R70 coming with one from the factory, but I could be wrong. They will for sure limit flow until the fluid is up to temperature.
 
i have heard some versions did but when I removed my 1997, I didn’t see one externally.
 
Dumb question, on the coolers lines do you have a thermostatic bypass valve? I don't remember a 4R70 coming with one from the factory, but I could be wrong. They will for sure limit flow until the fluid is up to temperature.
Just re-read. There’s not one on that year. I was worried it could be internal.
 
I'm curious as well. OP did a great job of covering all the basics.

Are there flexplate offset issues that might pull the converter TOO far forward? But did you swap flexplates, or just the t-case?
 
I just took measurements the tc can slide 1/4” back. Maybe a hair more which I’ve read is desirable.
 
I'm curious as well. OP did a great job of covering all the basics.

Are there flexplate offset issues that might pull the converter TOO far forward? But did you swap flexplates, or just the t-case?
I just took measurements the tc can slide 1/4” back. Maybe a hair more which I’ve read is desirable. I swapped all the parts from the original setup. Only thing different is in the transfer case. Presently I am 2 bell housing bolts and the cross member bolts away from having the transmission back out. I just can’t believe based on nothing being done inside and the pump surface inspection that the pump is the problem.
 
A modded valve body? ....stuck in relief circuit (fluid just pumped back to the pan)?
Nope. All stock outside of a tail adapter to the Dana 20 transfer case and a different spud adapter inside the transfer case.
 
Pulled the pump today. I’m so used to manuals. I have no idea what I’m looking at or for. The gears themselves look good and like they mate up. Outside of that, I’m not certain
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those pump gears look melted, like they were run without oil. they should be smooth on all sides (no scoring or grooves)
 
those pump gears look melted, like they were run without oil. they should be smooth on all sides (no scoring or grooves)

Correct, The converter hub wasn't engaged in the pump gear....But sitting on top of it forcing the gear into the Stator/Pump Cover.

Me & CrandallMG have been exchanging PM's & didn't know there was a thread.

Pointers for anyone in this situation......
*Fords are a PITA with their studded torque converter. Always make sure you can freely rattle the converter studs against the flexplate as you install the bellhousing bolts evenly.
*Never just force the trans to the engine, Ford units usually go on pretty easy.

The same force that was applied to the pump gear & pump cover was also applied to the Main Thrust Bearings rear thrust surface, Food for thought.

 
Correct, The converter hub wasn't engaged in the pump gear....But sitting on top of it forcing the gear into the Stator/Pump Cover.

Me & CrandallMG have been exchanging PM's & didn't know there was a thread.

Pointers for anyone in this situation......
*Fords are a PITA with their studded torque converter. Always make sure you can freely rattle the converter studs against the flexplate as you install the bellhousing bolts evenly.
*Never just force the trans to the engine, Ford units usually go on pretty easy.

The same force that was applied to the pump gear & pump cover was also applied to the Main Thrust Bearings rear thrust surface, Food for thought.

What's the likely resolution? Complete rebuild or can the affected pump parts just be replaced?

Just trying to learn.....
 
The damage was likely contained to the Pump Body, Pump Cover, Pump Gears, & Torque Converter.

You can start by back flushing the Cooler to see if it got contaminated & see if any debris is in the pan.
 
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