Transmission running hot with new 6.0 cooler
 

I bought this truck a year ago, and put guages on last month and notice after cursing on the highway for 30 minutes not towing, the temps would hit 220 degrees on a 90 degree day, I pull over and cool down when this happens. I installed a new by pass valve line on the side of the transmission, thinking it was open, but it did not fix the issue. Today I installed a brand new 6.0 31 row tranny cooler, 1/2 inch lines to connect to the 3/8 metal lines, new Magnafine filter, (old one looked old as hell). Drained torque converter, dropped trans pan, cleaned it, and magnet. Filled with Mobil 1 Synthetic ATF. Went on test drive after 30 mins at 70mph, 100 degree day, trans temp hit 198*EDIT (typed 189 by accident) degrees, this is still to hot. What should I do next? If I tow I bet the temps will shoot super high. Should I replace the metal Transmission lines next? Maybe they are blocked up? Truck has 203,xxxx miles, I can tell that a refurbished trans has been installed from ford. (who knows when)

1999 (late year) 7.3L turbo 4x4.

You don't provide year, model, engine, transmission of truck. If you did, maybe Mark Kovalsky (retired Ford transmission engineer) could post and give you some help.
If I recall correctly from a forum that I used to be on (as did Mark), the 189 degree temp may not be bad depending on which transmission and the conditions you're operating it in.
That's why it's good to have a signature on these forums with your particular equipment noted.

There's no way thats normal temp. If I tow it will go to hot right away. I messaged Mark. Hopefully he replies. I cant find the signature option...

According to Mark.....my 01 F350/V-10 and 4R00 trans and 6.o coller I am sake running at my temps. Tow a 36' 5th wheel sna sometimes the temp is 210 degrees....running normally down the road towing it is still at about 190 to 200.

I don't know what to tell you. 189°F is normal.

You can check cooler flow. Get two containers, each at least a gallon. You'll also need several feet of hose, 7/16" seems to work well.

Remove the cooler line at the rear of the trans. Put the hose over this line and aim the other end of the hose into container #1. Have a helper start the engine. In a few seconds the flow of fluid will be steady. Once it is move the hose to container #2 and keep it there for EXACTLY 15 seconds, then put it back in container #1 and shut the engine off.

If fluid sprayed out of the trans where the cooler line was removed, the test fails. If there is less than a quart of fluid in container #2, the test fails.

If fluid sprays out, not just a dribble, then either the bypass is stuck open or the cooler lines or coolers themselves are plugged.

Mark,

First off I really appreciate your response. MY BAD!!!! it hits 198 DEGREES! not 189....You mentioned the by pass maybe stuck open, but I have a brand new one on the transmission. I had a feeling you would say the temp is in range, but based off other posts it seems maybe 20 degrees + more than the average, but I take your word over anyone else. I will do that test this up coming Saturday and report back.

Two things come to mind first is does you cooler lines go through the radiator or just the cooler and second it may be a good idea to get a scan gauge to check to make sure your gauge you installed is reading accurately. Also where did you install the sending unit for the gauge..

There are no lines running to the radiator, they were running only to the stock Tranny cooler. That's how I have it set up right now with the new 6.0 cooler. I Just realized this may not be correct?? could this be the issue?

The sending unit screws into the port hole on the side of the transmission.

That temp seems pretty normal. I know with Allison transmissions, they like to run between 180*-210* (I run an Allison dealership). If anyone knows whats up, itll be Mark. His info is always spot on and very helpful.

Yes it could. The cooler inside the radiator is very effective. It removes a lot of heat. Without that cooler you're at a distinct disadvantage.

What are the temps outside?

I will do flow test this Saturday, I am guessing it will flow fine. If it doesn't ill install new lines. But regardless, I will also route the lines to go through the radiator as well, I will report back on results from both.

This is one of the transmission line inlet/outlet connections on the radiator.. Do I replace this connection with a different one? it looks blocked off..

https://cimg6.ibsrv.net/gimg/www.for...dfe8fe5403.jpg

Mark will know more on this but I think the 99 with the 7.3 didn't have the lines running through the radiator but most guys replace it and run the lines to make it work. By the looks of that fitting you might need to replace the radiator to make this work..

If it puts things into perspective better, I've got a 6.0L cooler and with a total weight I was a bit over 30,000lbs this weekend, hottest I saw the trans was 200* in 85* weather...

I've got it setup to go from the trans into a spin on filter, than a rad cooler into the 6.0L cooler.

PSDs build from January 1998 thru February 8, 2000, had only the oil-to-air (OTA) cooler in front of the radiator. Ford added the oil-to-water (OTW) cooler in the bottom of the radiator beginning with production on Feb 8, 2000. I'm guessing the previous owner replaced that radiator, and that's why the connections are there.

I stuck a flat head screw driver in the rusty ports and scraped a hole appeared... They look in bad shape I wonder if I can find replacement ones instead of buying a whole new Radiator.
https://cimg1.ibsrv.net/gimg/www.for...98789c947b.jpg

https://cimg3.ibsrv.net/gimg/www.for...b53f7dcd7f.jpg




http://shop.advanceautoparts.com/p/d...FQcxaQodKVgDVw

Or I could just go to a salvage yard pull the connectors and OTW lines off a truck..