I know there are plenty of threads on this subject but I wasn’t sure where to start. It’s a 2001 F250 V10 130,000ish miles. It seems to heat up when towing the travel trailer. The trailer only weighs 6600 dry. So loaded up, I don’t have a guess. But it’s not a giant load, the truck should handle it fine. I have a tranny temp gauge and it seems to heat up pretty quickly up any grade at all. I live and travel in oregon. Any body who has been to Oregon knows there is always another hill to climb, so it’s always up there on the temps and I don’t like it. So I was originally just going to replace the tranny cooler to a larger unit. But through my research found that may not be the issue. It may be the tranny fluid bypass line is stuck open and so no fluid Is going through the cooler at all. But have also read that those bypass lines don’t fail. Yes and everything on the internet is true. I climbed under the truck yesterday and followed the tranny cooler lines back and found that they go into what I believe is the bottom of the coolant radiator? is this the case? If so, and I wanted to put in a real tranny cooler could I just disconnect those lines and plug them into the new tranny cooler? That was quite the rant. Sorry for the long winded post just wanted to get it all out there.

 

First you need to tell us what the temps are to determine if you have a problem or not.

 

I am actually out right now testing empty city driving normal operating temps. Towing it seems to hover around 190-200. Hit a hill and it goes up to 210, that’s when I back waaaay off and maybe pull over to let it cool. I have had this tranny rebuilt once and I would like to not do again.

 

Ok. Drove around for 30 minutes and it got up to about 160. Empty, mostly city driving some hilly terrain and 50mph back to the house. That seems relatively normal correct?

 

Mark will be along shortly i'm sure to give his advice but he is going to tell you those temps are exactly where they should be.

 

What about towing. 210 seems close enough to the edge that it makes sense to try to get those down. The around town stuff doesn’t bother me it’s the towing. I have read a lot of marks posts and hope he does chime in. He seems well respected on this forum and others. Does my current cooler setup go through the coolant radiator somehow?

 

Temperatures are totally fine!

Steve

 

I have a 2004 F250 V10 and my old camper weighed ~6500 empty. I towed a couple times before I installed a Scangauge II on it. After the SG, I monitored trans temps. Climbing a hill/grade temps would rise into the 220's. I installed a 31 row trans cooler from a 6.0l and temps have never hit 200 since, even towing in 110+ degree summer heat.

 

Yes, your hot ATF leaves the trans then enters the bottom tank of the engine coolant radiator, then it goes to its own oil to air cooler in front of the radiator, then once cooled off goes back to the trans to start all over again.
With my stock cooling system I towed heavy TTs (9,500 then 12K lbs) for 40K miles and only ever saw 200+ a handful of times which cooled right back down when the climb was over, I also upgraded to the big 6.0 cooler and now it doesn't even get to 200 under any situation.

 

@WE3ZS if I was to install the 6.0 cooler or equivalent would I bypass the coolant radiator part or put it inline like the current setup is?

 

Put it inline like the current (stock) set up is. Replace the stock oil to air cooler with the new 6.0L oil to air cooler. DO NOT BYPASS THE OIL TO WATER COOLER IN THE RADIATOR.

Water is a more efficient heat transfer medium than air, so let the oil to water cooler in the radiator knock the brunt of the heat out of the fluid before it heads off into the oil to air cooler.

Make CERTAIN to perform a fluid flow test, incorporating both coolers and any other filters, thermostats, or as seen on TV doo dads in the transmission cooling circuit. Separate the return line entering into the sump of the transmission, from the transmission itself, and direct that separated line into a container having volume measurement demarcations that graduate in pints or quarts. The 4R100 return fluid flow spec is an easy to remember 1 gallon per minute, so if your return flow produces a quart in your container in 15 seconds, or a half gallon in 30 seconds, you can stop the test, as your flow is within spec. Replace the fluid you lost in the test to restore the transmission fluid level to proper spec.

 

Thank you all very much for the help. Anything else I should know before I go for it? Any recommendation for brand of cooler?

 

I found a 6.0 Ford cooler on eBay. Very simple install with lots of how-t0-do-its online.

Steve

 

How hot did it get? It will get hotter climbing a grade. You can go up to 220°F all day long with no problem at all. You can go up to 250°F for up to a half hour at a time with no problems.

They do fail. Summit has a rebuild kit for the bypass for around $25. It's really easy to install.

Yes, that's true. From there it goes to a small air to oil cooler out front.

If you bypass the excellent cooler in the radiator I guarantee that you will have a hot transmission. What you want to do is replace the small air to oil cooler with a cooler from a 2003-2007 F-Series with a 6.0L. That's a really big cooler and will keep your trans cooler. DO NOT remove the cooler inside the radiator.

 

It got up over 220 once or twice not to 230 though. I won’t bypass the radiator cooler. So go from the radiator to the new tranny cooler then back to the tranny. I found a mishimoto on Amazon for $336 that says it’s a direct fit for to 99-03 superdutys and is the same ish size as the factory 6.0 cooler. It comes with hoses that are 3/8” on one end to 1/2” on the other so no splices in the lines as other write-ups have done. If my temps are where I have previously mentioned would you say that the cooler bypass is currently working? Is it worth replacing anyways?