Transmission Temps?

[Big White Beast]

Just got my temp sender installed in the transmission line. Now the question would be what temperature ranges should I be looking at?



Truck is roughly 10,500 GVW.



No freeway today and temp ranges were around 150º to 200º.



Also the gauge maxes out at 250º. Is it safe to go near that or what is the max temp I should allow?



As a side note, I just noticed how filthy my keyboard has become since my BOMBing started (Frequent trips to the PC to see if I'm doing it right!!)



Garrett

 

[SlyBones]

Your gonna get varying opinions here. with the temp gauge in the hot line, here is what I see. Remember the auto makes heat while the TC is doing fluid coupling mode, and no or little heat while the lockup clutch is engaged.



1. I live only mile from the freeway and in the morning the gauge hardly moves of the peg until I get close to work.



2. Empty driving around town, stop and go, stop light traffic, will typically see 160-180.



3. Sometimes I see 200 empty if there is a lot of stop and stop driving and I never get up to any speed where there is any air flow through the cooler. Takes time.



4. With an 8K load ( 15K gcvw ) I can see 230 if I am driving a lot of in town stop and stop like #3 OR if I have to grind up a hill in second where the transmission is in fluid coupling the entire way.



5. I think about 260-275 is max you should ever see, with a large load, in fluid coupling, grinding up a large grade.



6. I think 300+ for a line temp is pull over and stop immediately.



7. Temps with the sender mounted on the pan are different than this.





The key thing is to learn when and how autos make heat. Know what your transmission is doing when looking at the gauge. And where the sender is mounted. Depending on circumstances 230 may be darn good or 230 may mean a call to Bill K. is in order.

 

[Fireman Dave]

I have mine in the line too, and I see similar temps to Slybones. I'm at about 14k with my trailer, and I saw up to 230 in slow traffic - when I was stuck in second gear - on my California trip in June. Watching that gauge on long mountain roads behind slow traffic with no chance to pass them was excruciating. As long as I could keep it locked up, it stayed around 150-170. I did see 250 a couple of times for a short distance. That worried me, but no problems and the fluid looked, felt, smelt, and tasted just fine afterward so I didn't worry about it.

 

[Gary - K7GLD]

HUH!



WHAT a bunch of wimps!



I just put a new temp guage in the outgoing line on my 727 3-speed... First HARD pull put the temp up past the 280* max, and burnt that sending unit to the GROUND!



transmission works fine, fluid looks and smells fine - guage is SHOT!





I *still* think that's the best place for the sensor, but might have to look into a aftermarket transmission cooler and a BIGGER temp range for my guage...

 

[Extreme1]

There have been posts regarding trans fluid temps and the effect it has on the life of both the trans and the fluid.



I recently pegged my temp guage on MY trip to California! (320!!) It was a stop and pull over, let it cool situation. But, pulling a heavy load up a long, steep hill will do that. The fluid looks and smells OK but I haven't had Fireman Dave taste it for me yet.



I wouldn't worry about up to 250. I have seen that on a hot day in traffic with a trailer in tow. The warning light on my '94 comes on at 265.

 

[SlyBones]

Big White,



Extreme1 is correct about the fluid life and temps. Find one of those charts. Dont worry about seeing 250 temps. But if you tow often and see these temps often, you had better be doing the fluid change intervals like recommented in the manuals for heavy duty service. Switch to synthetic fluids, etc.

 

[Midnite]

The service manual for my '92 says to put the transmission (in my case a 518) in either neutral or park if you stop for any length of time. Is this because of heat issues?



I really need to get a set of gauges...



Mike

 

[Fireman Dave]

Midnite,



It cools a little better in neutral than in park. I don't know if it does much cooling in park. Shutting down is the best way to cool it when it's in the danger zone. In stop and go traffic, I'll put it in neutral, though, to keep it a little cooler. TC lock-up cools it the fastest of them all!



Extreme1,



Save me a taste!



Dave

 

[Big White Beast]

Great info, Thanks

Talked to Bill K. Saving up for the TC/VB. (Injectors in mind already) When I install those I'll probably switch to synthetic. Too hard to drain the TC to change over now.



Only have 11k miles and did my first filter & fluid change. Had em raise the pressure and cut in my tap for the sender at the same time Save me from getting that mess in the drive. They had to work on it on the ground too. Their lifts couldn't raise it.



I don't tow much but when I do its heavy equipment. I'll be more careful then.



Again thanks for the info, now I know where I should be running around.



Garrett

 

[SnoKing]

I have two senders on one gauge with a switch. Outlet temp up to around 265 is OK. Pan up to around 180 is OK. Like others have said, lockup and a little speed brings temp right back down. I posted under towing forum "3rd tow" my recent traffic jam numbers. Snow King

 

[WyoJim]

Bill Kondolay says

This is a post of Bill's on the subject:



As a basic guideline i tell my customers 275 degrees is getting on the high side, when reading your trans temp from the front cooler line, ( the line that goes from the transmission to the heat exchanger) Keep in mind if you see temps going above that you should consider a secondary cooler

for your application.



When reading trans temps in the pan, Chrysler has their panic level between 230-240 degrees.



I usually consider 210-220 high in the pan. If you are seeing temps above that you should consider a cooler for your application.



Normal operating temps between 180-190 out of lock up in the cooler lines , heavy traffic, (stop and go) In the pan, normal operating temps should be 140-150 .



Bill