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<DIV>OK guys what does your trans temp gauge show for the temp on a normal drive on the highway?</DIV>
<DIV>Also how much hotter does it get when you tow heavy?</DIV></DIV>Edited by: John R
 

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John,


Unloaded, on a 20 mile drive at highway speed, @ 50 deg ambient, the tranny will get to about 110-120 deg.


I just did another test pull of my trailer through various speeds, mostly highway for about 36 miles one way. The ambient temp was 62 deg. and the tranny temp leveled off at 150-155 deg. The trailer is 6000 lbs. and the AC was on. Engine temp stayed at 205-207 deg.


Got to love a diesel, I passed a pickup doing 55mph with the trailer. When I passed him I was doing 75 and still climbing. About 2/3's pedal travel.
 

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Before upgrade 200 to two ticks off 200 in the 90's and humid .... Deep pan and transynd ...


Once it gets HOT it stays hot for awhile .... Will the Mag Hytec shed heat better ?? We'll see ...


Going to be tough to evaluate do to tranny upgrades also.but I'll report as the temps rise in New England ...


Mac
 

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Havent towed yet but 60 degrees outside 115-125 just running around. Takes a long time to run up any trans temp, I believe this is a non issue with an allison.
 

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This is direct from Allison's Website.


In normal duty, transmission sump temp runs in the 175-220°F range (79-104°C). Continuous operation above 220°F can shorten the life of the transmission fluid. TranSynd is recommended for continuous operations at elevated temperatures.
 

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During summer weather running empty 135 - 150 degrees. Pulling 5ver 175 - 190 degrees is what I have logged. Running Mobil 1 ATF with stock pan. Also the faster you drive, the warmer the tranny will get! Just my observations! Edited by: Runaway
 

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So Cal to Nevada in 120*+ heat towing 3500lb boat, a/c on bone stock with afe filter and gauges, 210* trans after hill climbs and 190* down the flats, 70-75mph with brakes slightly dragging on trailer (was wondering why mileage went down
). Normal so cal freeway driving 70-80 mph in 80* weather, 150-175*.
 

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I was having high temps when unloaded in stop n go traffic (220+). Replaced the OEM tranny cooler with a racing stacked plate oil cooler and it doesn't get above 180 now. I have seen very few people that have really high temps when towing. The high temps at idle was addressed by Allison with the upgrades that go along with the LLY. Some things I tried was adding a fan to the OEM tranny cooler, which had little to no effect. Changed to Transynd - little effect.


My father-in-law tows very heavy and never sees much over 200, but stop n go was killing me. That's why I increased the cooler size. The exterior is about twice as long and twice as thick and needed some line modifications and custom made brackets. Worth every penny as I no longer stare at the tranny temp gauge.
 

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this time of year in MI, I run 150*F for a 40-50*F outside. I ran that tempeven in the dead of winter after a 50 mile warm up with the winter cover on. I think that this is the optimum "cold" temp for the trans to run nicely. In the summer I have run her up to ~200*F in those 90* days. I haven't seen her climb much over 230* when summer towing.


HTH


Look below for details...
 

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Transynd in mine, just returned from 1400 mile round trip to TN,, towing 12k 5er never went over 175ish. Only got that hot in the mts of Kentucky. Stayed right around 150 for most of trip, temps were no higher then 75
 

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I have 55,000 miles on the truck, and have seen 200*+ 3 times. 230ish one time in the Mountains of eastern Tenn. last July with a CVGW of around 18,000#


Normal driving without towing/hauling it very seldom will see 170*. in fact it hit 150* last Thursday for the first time sense last October. Deep pan and Transynd helps at least 20*
 

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<TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNABLE="off">150 running empty... 170 the highest towing a 12000 lbs trailer...I got this trailer in Nov. so no real warm temps yet.</TD></TR>
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I rarely see anything over 150F untill i hit stop and go traffic, then my temp will hit 200F and stay there. As Mack has stated it takes a long time before temp comes back down especially if you are not driving fast. Remember guys, there is no airflow through the cooler below 35 mph. The deep sump pans made no difference at all (i tested both). I have heard from Transgo that Transynd and Amsoil have dropped temps although i have not seen these results but i know that synthetics will help alot under heat. We have used Mobil 1 motor oil in the 47RE Dodges with a lot of success and have used it in a lot of Ford Taurus.
 

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I currently don't have any transmission cooling issues, but I don't get the advantage of increased cooling at idle because my '04 is an LB7 and the '04 Allision mods are not activated on the LB7. This summer I will be in stop and go traffic in 100* + weather.


It seems like it would be an effective solution to increase trans cooling at idle by adding an electric fan w/thermostat to the existing trans oil cooler. A fan might be more cost effective and avoid any GM warranty issues compared to adding a deep pan or an upgraded trans oil cooler. There are a number of ATV manufacturers that use small fans like this to move air through the oil coolers at low speeds.


Any thoughts on this?
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I think a fan is a good idea, but i would put a toggle switch on it. I did a bunch of testing on electric fans a few years ago and found that they kick in rather late(too high of a temperature) and the biggest thing was ; electric fans do not play catch-up worth a darn. I would want full controll over the fan and if i even thought i was going to maybe run warm i would turn the fan on. Electric fans are more efficient when kicked on early(before the heat).


mike
 

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GMC2500HD


If you have an LLY the temps should be cooler if you have LB7 i don't think so. We will be playing with the G solenoid and see if we can't make it work.
 
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