Tranny temps

Ken / Claudia · 06-28-2015, 09:40 AM

I just did some before and after tests on cooling of my transmission when towing and thought I would let you know. To start with I spend big money in 2007 to have a custom transmission built so I could pull anything the truck is made for without tranny failure. In doing so they took out the factory cooler and installed a bigger one(2x's bigger) and placed it in the center of the grill area with a electric fan and a cab controlled on/off switch. I did not realize they disconnected the tranny cooling lines thru the radiator until a short time ago.
I was running temps of about 125 without towing. Towing the boat or TT it was normal to be at 190, higher, up to around 210 when pulling the 6% grades.
I had a shop put the lines back thru the radiator and than continue thru to the cooler. Without towing it is still around 125 but, takes longer to get to that temp. I towed the TT to the same place in the same temps of about 70 (outside air) as before with tranny temps right at 190. I now have tranny temps of 165-170 range. I did not have the electric fan on during either test pull. So far I have not pulled any 6% grades since the change.

shane772 · 06-28-2015, 03:49 PM

Sounds similar to mine except I still have the factory cooler. I bought the 6.0 cooler and lines to upgrade but my temps don't seem to warrant it.

Are you at all concerned that the trans temp never get truly "up to temp"? I was told w/o it getting up to or above 190℉ it could have problems? Something to do with the condensation not being evaporated???

bsmith0404 · 06-28-2015, 05:50 PM

I've seen similar info about the operating temps on the Allison, but mine seldom gets above 165, even in the mountains or going across AZ with outside temps in triple digits. I don't think it has as much to do with condensation as it does viscosity. trans fluids, just like engine oil, are rated for a specific viscosity at operating temps. Your engine oil is not at the proper viscosity for proper lubrication until it reaches 212. I'm assuming trans fluid reaches that at 190ish since that seems to be the recommended operating temps for most transmissions. I figured if it's running cool there isn't much I can do about it.

Ken / Claudia · 06-28-2015, 09:10 PM

I know that the tranny fliuds should be warmed up. But, to what temp I do not know. Mine is at 100 fairly quick than to 125 in a few minutes of driving. I will do some checking. I have seen a chart at the shop and only paid attention to the hot, to hot and burned up tranny temps.

Seabee · 06-29-2015, 03:34 AM

I do believe this is the chart that should go with this conversation:
http://www.bing.com/images/search?q=...jLA&ajaxhist=0

If I ever see 200 degrees while towing, the first thing I do when I get home is change the trans fluid. The fluid breaks down very quickly beyond that temperature.

jkoons · 06-29-2015, 05:48 AM

We have an 09 Chevy 2500HD,6.0,pulling 7500# TT,our temp generally runs what ever the outside air temp is (+-) 10* plus 100 (70*= 160*-180*)

**JRTJH** · 06-29-2015, 07:12 AM

Way back when (1972) in Southern California (Lancaster) our Dodge PU, 360 4bbl, D727 LoadFlight automatic transmission did well carrying a camper. When we switched to towing a 20' trailer, the transmission hump in the cab would get extremely hot. The service department at our Dodge dealer installed a larger transmission cooler in front of the radiator and all was good.

When we moved to Denver, CO, the first winter, the Dodge started "slipping" and "shifting erratically". I took it in, the problem was that when the service department in California installed the larger "external" cooler, they rerouted the return line to the transmission without including the "radiator portion" of the transmission cooling system. That never allowed the transmission to warm up. By including the radiator cooler, effectively, the radiator "leached" heat into the transmission fluid to help it warm up to operating temperature. In the "temperate" climate in SoCal, we never had an issue, but in the much colder temps in Colorado, the transmission seldom reached operating temperature without that "added warmth" from the radiator. Once they reattached the radiator cooler into the system and changed the filter/fluid, we never had any further slipping/erratic shifting. Coincidence? Maybe, but I think it illustrates that warming up to the "preferred operating temp" is just as important as not overheating the transmission fluid.

With my current tow vehicles, I've noticed on both my 2013 and now my 2015 SuperDuty, that the transmission is very VERY slow to warm up. The engine (gas and diesel) warm up much faster than the transmission. As an example, using the "oil/trans" gauges in the display, in about 5 minutes, the engine oil will be at 190 and the transmission will be at 80. After 15-20 minutes of operation, the oil will be at 210 and the transmission will be at 160. I'm not concerned with "normal distance driving" but wonder what the effect of short trips will have on the durability of the transmission if it seldom warms up to operating temperature for months on end. I never had any problems with my 2013, but that was only during a 2 year time frame. I wonder how it would have held up over the long haul without reaching operating temps regularly.

Ken / Claudia · 07-02-2015, 04:02 PM

John you bring up some good questions. This is what I found looking thru ford diesel owner sites about my tranny. It has a valve in it that is closed until the fluid warms up and than fluid goes thru the coolers. Others said their low temps are 125-130 normal driving. Others said as high as 170 normal driving without towing.
I just did a 350 mile trip without towing, highway speeds 60-70. Air temps 80-100 the tranny was running from about 150 to 170. For only about an hour air temps were near 60, speed was 45-55 and tranny dropped down to near 125. I did not find what ford has to say about the tranny temps.

roadglide · 07-02-2015, 08:19 PM

I have 2013 2500 duramax GVW is 21500 with 2015 Impact . I set instruments where it shows the transmission temp, coming home yesterday with 102 temperature 8 % grade was showing 172 is the highest I have seen it but going down hill it dropped to 167 fairly quick.

BirchyBoy · 07-02-2015, 11:05 PM

My GC Hemi has the factory towing kit. Normal temps with the trailer were 165-180. It spent a fair amount at 190 but did hit 220 a few times on long uphill pulls. I'm going to take it in for service next week and will have the transmission flushed and filled. I'm doing this more because the electrical snafu kept me from using the tow mode for 80% of my trip. I do need to see what Jeep says is an acceptable range.

gearhead · 07-03-2015, 05:11 AM

In my refinery days we had transmission fluid in some high speed (15-25,000RPM) gearboxes and most hydraulic governors. From memory (and it's fading) I think we considered 165 the ideal temp. Too cold and response would be affected, too hot would damage the fluid.
Our previous 2007 Chevy Avalanche ran 210+ when towing about anything. I had the Chevy dealer add the GM cooler that utilized the factory fittings and mountings, and went through the radiator. Cooled it down good.

Ken / Claudia · 07-04-2015, 10:45 AM

Here's what I found looking at what ford says. Normal tranny operating temps range from 150 to 170. The temps should/could be 60 to 90 degrees above outside air temps. So, with the later example outside air 60-70 and tranny temps at 125 are close. I read that lower than normal temps cause slightly higher fuel use but, none mentioned failure. I think the winter low air temps will be the test. There is something called a t stat that some use in winter to help bring tranny temps up faster than normal.

bsmith0404 · 07-05-2015, 07:08 AM

I noticed a big difference in tranny temps during the winter when using the winter grill cover. My problem is that it is not recommended to use the grill cover in temps above 40 (going off of memory) and I often travel where temps can vary from 10 to 50+ over the course of a day. I have also read about dramatic fuel pump temp increases when using the grill cover. Kind of a catch 22. I guess the best thing is to just take it as easy as possible and not apply too much torque to the transmission until it gets some heat into it.

Ken / Claudia · 07-06-2015, 09:15 AM

Good point, I see grill covers on pickups and trucks around here in winter or late season elk hunting. My tranny has been this way, (low temps without towing) since the new one was installed in 08 so, not real worried. I have a aftermarket torque convertor and 16 clutch plates instead of 8 now, also some type of master HD shift kit. maybe that helps.

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