Just recently installed a set of isspro guages and am a bit shocked by my trans temp readings. While driving around town (slow stop and go) the trans quickly gets up to 190-200 deg (haven't seen much over 200). As soon as I hit the highway it drops down to ~150 deg.

Temp sender is installed in the hot line right as it comes out of the trans. Truck is an '05 2500 CTD, auto, with no mods (yet).

Any ideas?

Thanks.

 

where are ya from. i thought mine was running hot until i thought about the ambient air temps. mine would bet to the 200-210s when driving around town too until i realized that the outside air temp was 100. might be something like that. but from what i read, 200 for a little bit isnt all that bad. just my .02

brett

 

mine has been running at that temp since may. I'm in the houston area. i've heard that as long as you don't go over 220 you should be ok. i talked to the dealer and they said that was normal. i wish i knew for sure.

 

Normal normal normal......and the "drop" in temp while crusing is when the torque convertor is in lockup. FYI I towed my race rig with a 1500 for around four years. I would see temps in the summer of 240-260 with that little 46rh while pulling steep grades (couldn't get going fast enough to keep it in drive and lockup. Granted that trans was built by a knowledgable trans tech I worked with, but even at those temps it gave me no probs.

 

The real issue is how much time spent at those temperatures.

Rule of thumb:
Trans fluid is generally designed to last 100k miles at 170F. Every 20F rise in temperature is a half life:
170F = 100k miles
190F = 50K
210F = 25K
230F = 12.5k
250F = 6.5k

Check your fluid reasonably frequently; somewhere between every fill up to every oil change. I would opt for every fill up.

I think the manual states fluid change at 30k; if the fluid looks discolored, I'd change it more frequently as it indicates it is getting cooked.

HTH

Tony

 

I'm in NM, about 5500 ft elevation. This morning it was mid-40s and ran at the exact same temps as it has on 80-90 deg days.

I agree that once the TC locks up, the reduction in friction is a large contributor to the dropping temps but I've never seen such a drastic difference in trans temps with mild temps, no A/C running, etc. I am considering putting an electric fan up front...anyone ever tried that?

Thanks.

 

When you're in slow city traffic and the temps get up to 190 to 200, try turning on the A/C. I think it will turn on the fan and drop your tranny temp.

 

hey, does anybody know at what temp the trans temp dash light comes on? would be good to know. thx

 

I can't answer that with certainty, but IIRC it was 260 degrees or so. Much higher than you would want it to be!! By the time you are warned, you are already burning it up.

I would recommend installing a tranny temp gauge and watch it closely when pulling in the heat.


This summer when it was averaging about 105 degrees here in N. Texas, my tranny temp would reach 180-185 just running empty.