As measured in the hot line...

I get nervous at 220, but it's yet to hit 230, but with the sudden 40* temp rise into the mid 80's, it's getting close in low-speed traffic (saw 220* today)... I'd bet with a trailer on it might get to 230.

I'm thinking to just knock it into neutral, get the revs up to about 1300 or so (get the cooling fan moving faster), and hold it there till the temps come down...

Maybe my cooler has a little restriction in it? My tranny builder did flush it with brake cleaner when he installed the tranny, but perhaps there's something I can do?

3.55 gears and a tight TC don't help. (though I LOVE the TC other than that!)

 

I don't like going over 240° as measured in the hot line. Perhaps if you shift to N when stopped in stop and go traffic the temps will stay down.

 

"I'm thinking to just knock it into neutral, get the revs up to about 1300 or so (get the cooling fan moving faster), and hold it there till the temps come down..." Yes, but why was it hot? What was your engine temp? What load? In what gear? What grade? If driving conditions were not severe enough to cause a hot transmission then you have an internal problem.

"Maybe my cooler has a little restriction in it? My tranny builder did flush it with brake cleaner when he installed the tranny, but perhaps there's something I can do?" What did your tranny builder rebuild? Did he flush out the brake cleaner with trans fluid before reassembling?

"3.55 gears and a tight TC don't help." Please describe your tight TC. Is your (new?) valve body a good match to the TC? Is the TC stall speed a good match to the engine RPM range in "low speed traffic" or is it just churning fluid until it couples at a high RPM? (Some heavy duty TCs have a high stall speed for gassers and are used behind the Cummins regardless by unskilled tranny shops.) Is your lock-up occuring as expected?

Have you been back to the tranny shop to ask their opinion? Did you see these temps before you got your new TC?

 

With just the tight T.C. your going to have higher temps, as you say!

I'm not an Amsoil fanatic, but their Universal ATF is an exceptional product, IMO. It's rated ATF +4, and with a Flash point over 425 * F., I would feel OK up to 250* (300* in a pinch) at the hot Line.

Depending on what fluid your using now...it may run cooler with a higher quality oil/additive package in it

Not the best senario, but at least you would not have to worry about the fluid boiling or coking up and causing other damage.

RJ

 

Rare.. engine temp is normal. it only occurs during in-town (semi-large town) traffic...stop and go type of stuff... once I get up to any appreciable speed (25 or more), it drops quickly down to a normal temp.

The tranny builder did a ground up DTT trans build to replace my ATS transmission that failed due to taiwan-made parts in it coming apart in a big way. The builder is top-notch, and highly regarded. His part was done right.

The TC is a DTT 89%, and is matched perfectly. It's tighter than the ATS triplelock I had before, and drives much better because of it. But, the tradeoff is that it's trying that much harder to move the truck at idle while against the brakes. Lock-up is perfect, but this ONLY happens below the 3rd gear 25mph lock-up.

The temps were close, but not quite as high, with the ATS. The tighter (better IMO) fluid coupling of the DTT converter explains the slight rise.

This transmission works so darn well I know there is nothing "wrong" with it.. However, there have been 2 ATS trannies in this truck prior to my ownership, and who knows how many other stockers.

Infidel (Bill) - yes, going into neutral does help noticably, but it's a pain, and I don't like shocking the driveline like that, going in and out or gear.. But I'm just overly paranoid.

Depending on the temps I see in town with a trailer and load, I may just go to synthetic to better handle the heat... the tinkerer in me wants to mess with bigger coolers, first... (I could buy a VERY nice stacked plate cooler for the price of 1 or 2 fluid flushes with synthetic!)

 

I mounted an in-bed cooler with a fan. This is an addition to the existing.
Works great!

 

I have seen 280-300+ in the hot line and never worried about it. I have heard this is within the normal range, for the HOT line. When the tranny was taken apart we did not find heat related problems. What you need to worry about the temp in the pan, which is probably MUCH lower. You may want to move your sensor to see what's going on in the pan.

Chris

 

Eskimo, thank you for the additional infomation. It appears you have the right equipment. I was not aware that DTT or ATS transmissions run hot in stop and go traffic. I don't know if my ATS does because I don't have a temp gauge, nor do I need one because it is not an around-town truck.

"it's trying that much harder to move the truck at idle while against the brakes"
First, is your idle too high? Second, I believe DTT uses a higher line pressure for a firm lockup. Does this pressure also occur during idle or slow speed driving? If so, it might create more heat. If the heat can't be adjusted out (What does your tranny builder say?) synthetic fluid might be your answer.

 

If anything, my idle is a bit low right now.

Not sure what my pressures are during light throttle operation, but I'd rather have higher pressure than low.

Honestly, besides the thinner wallet, I think this is just about the only drawback to a highly built transmission capable of taking 600hp (with the billet shafts of course).. and I'll gladly take that trade-off.

 

I believe you are quite correct that it is the tighter tc causing the heat for the reason you mentioned. About all you can do is do as infidel said shift to neutral above 230-240, switch to syn to provide better protection for the fluid due to the higher thermal stability, add a cooler but with no airflow when you are having the problem it may not help much unless the cooler has a fan. I do run syn in mine and do shift in to nuetral if needed but that really is not very often.

 

Did not realize you had full, DTT from your original thread. Glad it runs so well...but something sounds not quite right.
I spent over an hour in the left lane, against a concrete divider, on a 4 lane hwy in Dallas, moving 2 miles an hour...due to an accident. It was over 90* outside, with no breeze and 4 deep cars on both sides of me. My DTT (also 89%) climbed to 210* and sat there for the whole time. My only concession was to turn off the A/C. Traffic was moving just enough that I never took it out of gear.
This is the highest I have ever seen with my DTT ??

RJ