So I was towing my tractor to a job today and I starting noticing my trans temp was going up higher than usual (82F out side, tractor and trailer are about 12k and I was towing with OD off as usual). The temps jumped up to 210-215 after I got off the interstate and was hitting stop lights and driving on curvy backroads. I started noticing that the torque converter wouldn’t lock up unless I threw more throttle to it and let off, once I could get it to lock you could watch the trans temps start falling off. On the way home on the highway I could cruise at 60-65 and and was running 165 on my trans temp gauge. I have a stock cooler still but I’ve never had this issue with over heating pulling this load. I have a transgo tugger HD shift kit input in 2 years ago and a bigger trans pan. I just change out my 2-3 shift valve about a month ago after it got stuck with the steel transgo valve with no issues until today. Fluid is on the crosshatch and look nice and red and doesn’t smell burnt. So what could my issue be? I feel like it’s a torque converter problem. Truck has 140k miles but I don’t think this is the original trans cause when I did the shift kit it had the newer solinoid pack in it. Thanks in advance.

 

Btw it’s a 99.5 f350 with 3.73 gears and 35” tires.

 

I see where you say it reached 215°F. Normal operating temperature is up to 220°F, so this is normal.

Do you have a transmission cooler inside the radiator? Ford didn't install one in the 1999 models (early or late) and that turned out to be a big mistake. The radiator cooler is absolutely needed to keep the trans cool. Many trucks had the radiator updated to one with a cooler.

 

No I don’t have the oil to water cooler in the rad. Soon as I posted I went to look and I don’t. My 03 I sold 2 years ago did and I guess that’s y I’m not used to having this problem. I bought a Hayden 11”x12” auxillary cooler on the way home cause I have to haul this same load 200 miles this weekend and I have been wanting to drop in the 6.0 cooler but haven’t had the time and really wasn’t having problems till today also. I’m gonna mount it right up front under my push bar/winch and hope that that will keep it cool till I can do something better. My 03 with the same size auxiliary cooler never got above 190 towing this same load and I was actually running a hot tube on it all the time I was in my 40hp tow tube on my hydra today.

 

It's smart that you're vigilant about the trans temp, but 215 isn't dangerous and seems pretty acceptable for the load & driving conditions, especially with big tires.

 

It totally blows my mind that ford was so ignorant to not put the oil to water cooler on these. Every ford I own and have owned has had the trans run through the radiator.

 

Mark, what’s the normal operating range for temps on the 4R100 and what temp should we start worrying about?

 

Normal temps are between 160 and 220°F. You can go as high as 250°F for no more than a half hour at a time.

If it does get too hot idle or fast idle in park or neutral. Do NOT shut the engine off when the trans is overheated. That will trap heat inside the transmission and cause damage.

 

So I found a dorman 918-216 6.0 cooler at the Autozone hub and picked it up today after deciding I didn’t like the idea of throwing that cheesy Hayden auxiliary cooler on my truck. Bought some 1/2” power steering hose and stopped by the hardware store and bought a some 3/8 barb to NPT male and a 1/2 barb to NPT female for the change from 3/8 to 1/2. Finished it in just over an hour. I didn’t really get to take pics during the install cause I’ve got so much to get ready before towing the tractor and tools over to our lake property to work. But I snapped a couple of the final product. Took a 30 min drive and drove her kinda hard and my trans temp was just barely beginning to even register so I think this should have me fixed up.

 

Not bad man..good job. A word of advise though...either, loom or get heater hose and splice, to cover any trans soft lines that have ANY vontact with metal..etc. Doesnt take long for the constant rubbing to wear a hole.

 

already wrapped them up this morning. I was to tired to go digging through the shop for hose scraps last night. I’ll let y’all know how my temps do on sat.

 

Glad to see you think you have this figured out. Good luck.

 

Problem solved! 6.0 cooler makes a big difference, better than the Hayden. Just be sure to get the later radiator with the transmission oil cooler when it comes time to replace.

Given that you mentioned curvy backroads; when towing with the stock cooler, road speed is a big factor. The OE cooler can get the job done only if it gets plenty of air over it.

 

Sry I’m just getting back with the results of the new cooler been out of town a week and have **** poor service where I was. 6.0 cooler did wonders 12k pounds was nothing for it ran 160 in the flats hit 175 in the hills only cause I couldn’t roll on cause I was following my dad in his 82 F100 that was towing way more than it should and his was struggling a bit. Was nice being able to drive the truck however I wanted without constantly staring at the trans temp.







Cleaned her up good tonight at work.

 

I have the exact same gauge setup, just in a different order.