Transmission Temperatures Averaging 185-195 degrees F Unloaded

[CTRice]

I have a 2006 Laramie 4x4, 48RE, Short Box, SRW, Quad Cab. 77,000 miles. Add ons: Extra Capacity Aluminum finned Trans. Pan, Trailer Brakes, Auxiliary Gauges, Screening over Radiator and Intercooler.

Lately, I have been seeing transmission temperatures averaging 185 to 195 degrees unloaded. I changed the trans fluid and filter per the owner manual and frequently clean the screen over the radiator and intercooler.

I am concerned that I may find that my transmission temps will exceed 200 degrees and cause damage or failure when I tow my 26 ft. fiver this spring. What should I do to lower transmission temperatures. I have several new, older model (A-275) trans coolers in my spare parts bin. Could I add one of these to the trans cooling circuit or should I seek another solution??


Another question: Last Winter I got stuck in the snow and had to shift in and out of FWD several times. As a result, now my Four wheel drive indicator light comes on, but the "Lock" light does not illuminate. Does anyone out there have an idea of what could be the problem??

Its been quite a while

 

[jelag]

My BIL tows 15K lbs with his dually... he had to put a larger pan and upgrade the transmission cooler to keep the temperatures in an acceptable level... my guess your going to need to make some changes to keep the temp down... as I remember... he wanted to keep the temperature under 250 *F.... above that number the transmission fluid would break down...

I've also had problems with the lights on my 4x4 system..... I've been under there several times cleaning connections and have finally given up... its always been dirt... and I couldn't keep it clean enough.....

 

[rscurtis]

Where are you measuring the temperature? What was it previously, assuming you made some changes?

 

[cerberusiam]

As was asked, where are you measuring temp? Location, location, location is the key.

A temp of 185-195 is not unusual, its right n the middle of the operating range. How and where you are driving will effect that also. Seeing those temps with slow and go driving even in 30-40 degree temps is not unusual, the TC generates 90% of the heat in the trans when it is unlocked. You have to read trans temp in relationship to driving conditions. Compare temp chnage sin lcokup at road speeds or you will not get a solid reading to judge by.

The stock system of heat exchanger, front cooler and stock pan is more than capable of keeping temps in check at max GCVW in 100+ degree temps. The key is making sure they are working correctly and efficiently. The first thng to do is make sure all the coolers are clean and free of debris, that will raise temps a lot of if it is clear. The second thing you need to do is get rid of the anti-drain back check ball, it will collect trash and spike temps. The 3rd problem area is the thermostat in the front cooler, if it sticks in bypass mode temps climb fast even with light loads.

 

[p-Bar]

installing the sensor before the cooler is scary to monitor . most will install in the pan or after the cooler . Follow Cerb's suggestions that check ball will slow down the flow. I installed a lock up switch which has helped tremendously remember you are generating a lot of heat when you are using the fluid to couple your power. I pull a14k 5er and temps stay down as long as the torque converter is locked up. Here is a thread on a manual over ride switch for the fan this is good for backing up as I really see the temps spike. I will be installing a Derale aux. cooler with the fan to help things.
https://www.turbodieselregister.com...sion-Temperature&highlight=fan+overide+switch

 

[CTRice]

Thanks for the timely replies.
I went through my archives and found that my gauges are BD X-Monitor with an "A" pillar mount display.
I installed this unit in 2006, so I had to review the installation manual in order to answer your questions.

This set up for transmission temperature readings goes through the ECM connector wiring and uses the truck's OEM sensor to measure temperatures.
I have read your replies and plan on exploring some of options thus far.
Please let me know if I should/could add an auxiliary cooler, or if there are more effective methods for checking transmission temps.
Thanks again,
Chuck

 

[cerberusiam]

That means your whole trans tmep is predicated on the ECU interpreting the signal from the temp\pressure transducer on the VB. Those transdcuers are the single biggest problem in the whole transmission and can frequently return erroneous information. Am ECU flash can change what you se eon the monitor and it is hard to tell if it is a real issue or just electronic inteference.

Before even considering an aux cooler you need to vlaidate the trans temperature. The most effective and pro-ative place to read the temp is the cooler output line (front cooler line on the trans) and use a quality analog gauge like ISSPRO. Reading temp in the cooler output line will give you readings for both cooling system efficiency plus TC load, and, will allow you to adjust driving style as needed.

 

[p-Bar]

I agree with Cerb. Do a stand alone monitoring of the fluid. A lot of folks say to monitor after the cooler or in the pan. I believe you should do it pre cooler so you monitor hottest temp and know if you are cooking your fluid. My. 0.02

 

[Ozymandias]

I think 185 is pretty normal, it's close to the engine water temperature. Because of the water/oil heat exchanger and the thermostat in the oil/air cooler the fluid temp will mostly be in this area. Mine does it also, with no load just rolling easy the freeway.


Or am I wrong?

 

[p-Bar]

I agree Ozy

 

[cerberusiam]

Again, it all depends on where the measurment is taken and ambient conditions. 180-185 in the cooler output line in lockup mode with a light load and ambient temps over 70 degrees is perfectly normal. That is usually 10-12 degrees higher than actual pan temp in the same conditions. When the temps drop down to 60 F or lower the cooler line temps will drop also. Anything under 60 F ambient my cooler line temps rarely exceed 170 F.

The heta exchnager will genrally pull the trans output temps down to water temp, it is pretty efficient. The fornt cooler operating at peak efficiency will generally take another 60 degrees off the water temp. Cooler return is usually in the 130-140 degree range. The fluid then lubes an cools the trans drive train and dumps back to the pan to be mixed with overflow from the converter circuit. In lockup mode and normall balmy ambient temps that adds another 30-40 degrees so pan temps are frequently right around 170-175 degrees.

This is all measured using standard analog gauges which can and will differ from the readings obtained by the transducer. They always seem to read higher than the analog equivalents when working correctly, generally 10%. When they go bad that could go way high or way low depending on the failure. What is "normal" has some dependencies.

 

[rscurtis]

I have the same setup as CTrice, and it normally runs 130-145*. Highest I've ever seen is about 165* in summer traffic. It might be worthwhile to confirm that the air cooler is actually working and not just bypassing the fluid due to a stuck thermostat.

 

[CTRice]

Thanks again for the information and direction. I am going to study my Service Manual CD to get a better understanding of the trans cooler thermostat and the anti
drain-back check ball. I am also planning on exploring the installation of an ISSPRO analog gauge. I want to give a special thanks to cerberusium for your ideas.
I'll keep you posted on my progress. I'm sure I will have more questions.