transmission temps getting warm

[royster]

hey folks,



under "normal" driving conditions - around town and on the highway - the transmission temps vary between 115F and 150F, depending on ambient temps, the load, etc.



yesterday, i noticed the temps creep over 180F. i was on a steep, wet logging road in 4-hi in first gear with hardly any throttle. the ambient temp was around 65F and the truck was empty. i am not alarmed, although i am concerned about the future. i am imagining myself on a steeper road on a hot summer day with the truck loaded and in 4-lo.



the transmission is a dtt-built 518 hybrid, 91% tc, with a mag hytec deep sump (not double deep) and the stock transmission cooler. might i be looking at a second cooler come the summer camping season (and i don't mean a beer cooler)?



any thoughts welcome,



cheers,



roy

 

[dan brooks]

Idling and low RPMs will really heat the transmission up. The converter is slipping a lot at low RPMs, and that is where the heat comes from. Add steep hills and it will heat up fast.



Before adding the under bed cooler, it wasn't unusual for my temps to hit 180-190* in heavy stop-and-go traffic during the summer (my sensor is on the output line - the hottest the fluid will get). You can see pics of my cooler in the "Reader's Rigs Gallery" (click on the link under my username to the left <------).

 

[cerberusiam]

Tight converter and low rpms will generate a lot of heat. The temps you saw are about right with the trans fluid flow being low. Getting the rpm's up should help with the cooling. The trans temp is going to be somewhat sensitive to engine temp as the main cooling is done with engine coolant. Increase the engine speed and fluid flow will help keep things cool. A secondary cooler is a good idea with the 518 under any circumstances.

 

[royster]

thanks dan and cerberusiam,



i didn't connect the low speeds, reduced fluid flow and tight converter. of course, now it makes sense!



i will investigate an under-bed cooler for the summer.



cheers,



roy