After finishing all my reliability mods (head studs new oil cooler, welded up egr cooler, cleaned turbo, stand pipes and dummy plugs, and others). I added an SCT ITSX. Running around empty or pulling my 5er I get EOT &ECT of 8-10*. On the first long trip with it running empty on the street tune, we drove to Gatlinburg Tn. And as usual anytime I go there we drive up to the big look out close to the top. While climbing the hill at about 30mph at one point the coolant temps got up to 215* so I pulled off the road to let it cool a bit and it only took a couple of seconds to come down and never got that high the rest of the way up. All the way an 8-10* spread.

Last weekend we took our 5er to the in-laws. I put in the 55 hp tow tune. As soon as I got on the interstate and climbed the first hill accelerating and the ECT got up to 220* and went back down to about 205* quickly and never got above 210* after that for the rest of the 2 1/2 hr drive. Even with a lot more and even bigger hills.

Before we came home I wanted to see if stock would keep the temps from jumping that high and to see if there was any other differences. As soon as I get on the interstate, anther big hill accelerating. Temp shot up to 222* and quickly back down and stayed below 210-215*. And I really missed those ponies.

My conclusion after the round trip was that the ECM had to learn the new strategy and driving demands and once it did that it was able to keep everything at a good level. Does this sound correct to you or do I have anything to concern me?

Ps. The highest deltas I seen was about 12-13* temp spead and that was while coasting down hill and it only took a couple of seconds for the EOT to drop to within 4* of ECT

 

Those temps sound somewhat fine. Only thing I will add is that my old 6.0 and my current 6.4 have never seen coolant temps that high unless there is a trailer hooked up. But if you were working it hard while empty, I guess that would be possible.

 

On the interstate empty at 70-75 mph the highest I ever seen was 202. But climbing the mountains I would say its putting the engine under a good bit of load constantly on and off the peddle going around those hair pin turns.

 

You are fine at this point. If you just want to do something, maybe see if a thermostat changeout brings them down some, but it really isn't necessary.

 

In the mountains it is not unusual to hit 220 towing.... did you hear the fan come on strong then? That thing MOVES the air!!!

 

Yeah, the fan was blowing good. But like I said the truck only got that hot one time during the each trip. Even after stopping to fuel up and getting back on the interstate it never even came close to those temps when getting back up to speed.

 

Kinda sounds how a sticky thermostat would act

change thermostat

 

Well that's 2 for a new thermostat so I guess that's what I'll do. I can't remember if changed it when I did the coolant flush last. " I know I took it out, but did I put in a new one?" getting old sucks.

 

Put me down as +3 for the thermostat being suspect. Especially with a 6 year old truck with over 100k miles on it. It's a mechanical part that will quite working at some point.Just in case your wondering, the part number is 3C3Z-8575-AA and should be $20-$25 at your local dealership. Assuming they want your business and not just your money.It beats the alternative

 

"I'd rather die while I'm living than live while I'm dying" JB

 

"I'd rather die while I'm living than live while I'm dying" JB

Thanks for the part #

 

Did you use Tow/Haul mode when going up some of the steeper grades? I've noticed on my ride that if I don't use Tow/Haul mode for steeper grades the EGT's go higher and take ECT and EOT along with it. If I hit Tow/Haul the torque converter unlocks raising the RPMs, increasing the boost, and dropping the EGTs along with the ECT and EOT. When going up steep grades, RPM and boost is your friend as they help move more air through the engine and help keep you temps down. That's if you're trying to maintain 55 mph. At slower speeds on extended pulls empty, I've gotten as high as 210-212 degrees ECT.

 

Tow/Haul doesn't unlock the torque converter...it changes the shift points of the tranny. If you stomp down on the skinny pedal you can/will cause the TC to unlock. With that said, indeed the higher RPM's will keep your EGT down...which isn't that big of a deal if your not exceeding 1100F for long periods of time (several minutes). Staying above 1200F isn't healthy...but for short periods isn't the end of the world either. When your hitting 1300F and up...the longer your on that side of the heat range...the more damage your doing to aluminum parts (pistons).

 

Thanks for the correction Z.