Cooling lines not flowing

[R&T Babich]

I was changing transmission fluid, like I have done several times before.
Trans has been working fine, just time for a fluid change.
I pulled a cooler hose and added a drain hose.
I was pumping fluid into a container while replacing fluid via the filler tube.
The hose got kinked and the fluid stopped flowing into the container.
After stopping the engine and cleaning up the mess I set up to resume.
Now the trans fluid is not flowing out thru the cooler hose.
Did I blow some sort of pressure valve in the trans?
The trans shifts into gears, but now no fluid is flowing thru the cooler line.

 

[R&T Babich]

Oops, new to this forum, thought the info would show on my ID.
I have a 2003 Expedition XLT 5.4L with the 4R70W trans.

 

[stamp11127]

Check to see if you have a cooler bypass valve. The shop manual shows one with the aux cooler if installed. Location is on the right side of the transmission.

 

[R&T Babich]

Just crawled under the car and I don't see anything that might be a cooler bypass.
The 2 cooler tubes come out of the right side of the trans, one right above the other, and go straight up to the radiator/aux coolers (towing package).
There's no cooler bypass tube or any type of bypass block in the lines.
The trans has been working great - 146k (knock wood).
I just took a short/slow trip around the block and it seems fine.
Took the cooler line off again and there is no fluid flowing in the line.
I won't be driving it until I get this figured out, really strange.
Tomorrow I'll try taking the tubes off the trans and blow some air thru the tubes/coolers.

 

[stamp11127]

Check the trans fluid level - take three readings. Make sure you are level ground also.

 

[R&T Babich]

There are 2 places I can hook up a drain hose.
I must have used the connection before the coolers in the past.
I have new hose fittings/drain lines and for the original post I connected after the coolers.
When I connect before the coolers there is normal fluid flow - a bit faster than I can pour in quart bottles.
When I connect after the radiator/tow package coolers the flow is a trickle.
If I select reverse gear the trickle increases, back to park and it slows down.
Does anyone know if there is a thermal flow restrictor in the tow package cooler?
I can blow lots of air thru the coolers.
I can't see the tow package cooler very well, but it doesn't look like there is a thermal flow valve in there.
Maybe the cooler has some sort of internal restriction.
The fluid has always looked fine when I change it.

 

[R&T Babich]

After many tests and gallons of fluid I think I have a handle on the problem. I don't think the hose kinking was any problem. It wasn't that way for long. I do have a flow problem. The fluid did look a bit darker than usual, not enough was coming out at first to really tell. I isolated the radiator cooler from the tow package cooler and tested the flow thru a clear hose into 5 gal jugs - my usual setup. With just the tow package cooler in the line the fluid flow is normal - a little faster than I can pour in quart bottles. Switching over to just the radiator cooler the flow is very slow, about as slow as you can pour syrup on pancakes. I can let the engine run for several minutes and maybe half a quart has come out. With the tow package cooler I have to start adding fluid right away. Blowing air thru the radiator cooler both directions sounds like a lot of air is flowing, but I tested the fluid flow 3 times and every time it is very slow. The radiator cooler is restricted somehow.

 

[Mediamonkey11]

Depending on whether the radiator is original and how many miles are on it, I'd cheange it out ASAP. Could be rotted and just dying to dump coolant into the trans rendering a much larger repair than just a rad...

 

[R&T Babich]

I'm not going to change out a perfectly good working original radiator just to replace the trans cooler in the lower tank. I've never liked the idea of having the trans cooler in a radiator tank because I know a couple of people who have had their trans ruined by a cracked radiator cooler. So time for an upgrade. Actually I already did something similar on a '75 E-150 C-6 that I used for towing our boat and never had a problem with the trans until 185k when the output shaft bushing spun.
The setup I'm testing is trans fluid goes thru the tow package cooler, a TG8A filter, a large Borg Warner flat plate cooler and back to the pan. Currently a temp gauge sensor is installed in the filter mount between the coolers. Ideally I should move the sensor to after the coolers. I'm thinking of adding the same temp gauge to another car so I might put it in after the flat plate cooler, test for awhile, then take the other sensor out. I really did not want a large 2" gauge sticking out on the dash and found a Koso BA024B11 on Amazon for $38. Works great and uses a small rectangular digital display that velcroes to the dash. Got the cooler at U-Pick Parts for $15, flushed it out and pressure tested - working great, it's twice the size of the tow package cooler.
Took the car out for a road test - 90 deg ambient, no trailer, flat, 65 mph - temp gauge 120 deg (gauge read 88 when started engine).
Remember the temp sensor is between the coolers. I want to get a second gauge and see what the temp drop is after the second cooler. I'll get more readings on some hills and with a trailer soon.

 

[Mediamonkey11]

Aah, didn't even think of bypassing it, way better!!


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