Transmission temperatures seem high

[JValdez]

So is it best to put a temp sensor in the pan or in the cooler line? In reading this post and according to y-knot everyone hear has either a bad gauge, bad sensor placing, or a transmission cooling problem. If this is such an issue why didn't DC put a temp gauge in the cluster?



I'm not slamming y-knot. I've seen his transmission cooler and I will one day install one. I'm sure he has alot of knowledge through his testing but it seems everyone is near the same temp on their gauges so I was just trying to figure where the problem is or if there is one.

 

[rgreen]

Have noticed about the same here. Speaking of high trans temps. Have learned to go easy in city driving and shift to neutral for any extended stops. Long lights included.

 

[NLeach]

we shouldnt have to do any of that. $40k+ truck that needs to be shifted to neutral to circulate transmission fluid because it begins to overheat,not in the manual. I got an extended warranty and no mods til its over so DC can replace the transmission when it goes.

 

[rgreen]

High trans temps are not good. That being said those of us that have the temp sensor in the hot line know that it can spike quickly and descend just as quick. Stop and go driving with a heavy trailer is certainly a challenge. The one thing I did not mention was to turn OD off in the city so the TC can lock up. Notice that as soon as it does the temp drops. If I was doing much driving in the city I would certainly go for the powered trans cooler. As it is I am carefull and aware that if I find the stress too much I can put the sensor in the pan where it probably belongs and would give a better indication of actual trans temps.

I use it though as an indicator and have learnt to drive carefull. No you do not have to but it will last longer.

 

[cerberusiam]

So is it best to put a temp sensor in the pan or in the cooler line? In reading this post and according to y-knot everyone hear has either a bad gauge, bad sensor placing, or a transmission cooling problem. If this is such an issue why didn't DC put a temp gauge in the cluster?



I'm not slamming y-knot. I've seen his transmission cooler and I will one day install one. I'm sure he has alot of knowledge through his testing but it seems everyone is near the same temp on their gauges so I was just trying to figure where the problem is or if there is one.

Sensor goes in the hot line of the trans cooler for best results.





While y-not's info is pretty good it is a bit dated for the newer trucks and fluids. Two different inividuals that build diesel transmissions for a living assure me the ATF+4 is capable of with standing short spikes into the 320 degree range with no issues. That is not saying you can run at that temp frequently. If you are consistently seeing those temps then an accelerated maintenance schedule is required.



Trans hard parts are not as effected by the temps as was previously stated. We are measuring fluid temps not trans temps. Even though the fluid temp may hit 300, measured at the output line, that fluid is cooled before it is routed back to the trans. It will generally be at or slightly above engine temp which should fall within its range of operation.



While extra coolers are needed at times, unless there is no otherway to keep the trans cool they are really a waste of money. Around 90% of the heat is generated in the TC while not locked up. The fluid goes directly from the TC to the cooler so as long as the overall trans temps remain in check extra coolers are not needed. While the TC is locked heat generation drops dramatically so it follows that achieving lockup more often would be a better and more desirable choice. A TC with better effiiciency will also help as it spends less time spinning in fluid coupling to generate the speed and thus reduces the amount of heat generation.



Extra coolers are really addressing the symptoms and not the root cause. It will cost more to address the root issues but in the long run you will have a better performing trans and truck as an end result.

 

[JordanB]

That makes sense, Cerberusium. Or maybe I just want to believe everything is working fine. :-laf