Normal Transmission Temperature?

[nomad297]

I own a 2004 2500HD Silverado with the 6.0 gas engine. They must have run out of the correct instrument clusters while mine was on the line, so I was blessed with a transmission temperature dummy light instead of an analog gauge.

I recently had to replace my cluster due to lighting and gauge problems, and the new OEM cluster (not rebuilt) came with the transmission temperature gauge. Everything on the new cluster works fine, but I don't know where the needle should rest at cold and where it should hover at normal temperature for the transmission. I've searched the web and read many opinions which vary from 160 to 180 degrees for normal temperature, but that 180 seems too high to me. My 2005 3500HD Duramax's transmission temperature always seems to be around 140 degrees.

I just don't know what it should be. Can somebody please let me know?

Thank you,

Bruce

[nomad297]

Dannyabear1 wrote:
Did you switch out the sending unit to the correct one for a gauge?
My '03 1500HD (6.0 & 4l80e) runs around 150 normally and around 200 when towing 7500# camper.

The correct sending unit is already installed. It is the same unit for the light and the gauge.

Bruce

[Dannyabear1]

Did you switch out the sending unit to the correct one for a gauge?
My '03 1500HD (6.0 & 4l80e) runs around 150 normally and around 200 when towing 7500# camper.

[Charlie_D_]

You likely have GM Dexron III fluid in the transmission. Around 05 GM retired Dex III and replaced it with Dexron VI, which is a full synthetic fluid and backwards compatible with all transmissions that used Dex III. If you drop the pan and change the filter, I would recommend refilling with Dex VI.

DEXRON-VI is a mix of Group II and Group III base oils plus additives. A true synthetic will contain Group IV base oils which are called PAO (polyalphaolefins). TranSynd and the other TES-295 fluids all contain PAO only. Base oils are divided into these groups based on sulfur content, viscosity index, and amount of saturates.

To learn more about Base Oil Groups, go to API.org (American Petroleum Institute).

[wintersun]

With my Duramax the trans temp is at least 60 degrees above the ambient air temperature when it peaks. As others have mentioned when the outside air temperature is higher the cooler on the transmission will be less effective and the ATF will be hotter. Same thing with higher elevations where there is less air. The flash point for ATF is over 350 degrees so that is not a concern.

I do check to be sure the ATF level is correct after a fluid change. When I got my truck new from the dealer the prep person had under filled the ATF and I needed to add nearly a pint. I had trouble getting the ATF up to 160 degrees to do the fluid level check as recommended by GM which says to check the level with the ATF between 160 and 200 degrees, or "normal operating temperature".

[BurbMan]

By popular request, here is that outdated chart from the 70's:



Nomad, I have the same 4L80E in the Suburban. Running empty in cool weather, temp is about 150, will get to 175 or so when towing and won't get any hotter than 200 when pulling a long hill with the 8500 lb trailer in the summertime.

You likely have GM Dexron III fluid in the transmission. Around 05 GM retired Dex III and replaced it with Dexron VI, which is a full synthetic fluid and backwards compatible with all transmissions that used Dex III. If you drop the pan and change the filter, I would recommend refilling with Dex VI.

SteveB wrote:
I remember reading somewhere that the GM gauges were really "idiot gauges" in that they give the impression of a gauge but with maybe 3 or 4 positions for the needle.

I believe you are thinking of Ford gauges, many have reported them to be glorified idiot lights.

[Charlie_D_]

CampingN.C. wrote:
Doesn't sound off to me. As I said in my post, I run around 100 over ambient temp while towing. Our rigs are virtually identical.
You're saying your at 150 on a 50 degree day, if yours is off mine is too.
This is my second truck with the 4L80E and I've yet to get either one "hot" with many trips up 421,321 and 221 in the NC mountains.
(knock on wood)
Before the addition of the gauge, when you just had the light, did the light ever come on to warn of a high temp? I'm guessing not.
Remember, the 4l80 was GM"s biggest and baddest before the Allison. It was used in the 3500's

X2-My transmission runs between 80-90 deg. F above ambient.

[captnjack]

Your truck will probably go into "limp" mode once the fluid gets too hot. I think it happens up around 275 degrees or so. My 2002 Suburban has this feature so I assume your newer truck has it too. No one wants to run steady above 250 I'm sure. But I think some people worry too much about this temperature. I towed about 6000 pounds up Wolf Creek Pass last summer. I got to around 235 degrees. I did pull over for peace of mind. Normal range (flat ground) was 180-190 when towing.

[SteveB]

Bruce,
If your original sending unit was not replaced then the gauge would not work properly. I remember reading somewhere that the GM gauges were really "idiot gauges" in that they give the impression of a gauge but with maybe 3 or 4 positions for the needle. I'll see if I can find it.

[nomad297]

CampingN.C. wrote:
Doesn't sound off to me. As I said in my post, I run around 100 over ambient temp while towing. Our rigs are virtually identical.
You're saying your at 150 on a 50 degree day, if yours is off mine is too.
This is my second truck with the 4L80E and I've yet to get either one "hot" with many trips up 421,321 and 221 in the NC mountains.
(knock on wood)
Before the addition of the gauge, when you just had the light, did the light ever come on to warn of a high temp? I'm guessing not.
Remember, the 4l80 was GM"s biggest and baddest before the Allison. It was used in the 3500's

Thanks for the reply.

You are correct -- the high temp light never did come on. I will hold off on changing anything until I know for sure it is off.

Bruce

[CampingN_C_]

Doesn't sound off to me. As I said in my post, I run around 100 over ambient temp while towing. Our rigs are virtually identical.
You're saying your at 150 on a 50 degree day, if yours is off mine is too.
This is my second truck with the 4L80E and I've yet to get either one "hot" with many trips up 421,321 and 221 in the NC mountains.
(knock on wood)
Before the addition of the gauge, when you just had the light, did the light ever come on to warn of a high temp? I'm guessing not.
Remember, the 4l80 was GM"s biggest and baddest before the Allison. It was used in the 3500's

[nomad297]

Thanks, everybody. Based on your comments, it is obvious to me that my new transmission temperature gauge is inaccurate. I will have to buy a Scanguage to get an accurate reading and reset the analog gauge needle to reflect the correct temperature.

My gauge is showing 120 on the highway at 60mph with an ambient temperature of 50 degrees without a trailer. After adding the 8,000lb trailer and driving the same relatively level highway at 60mph with the same ambient temperature, the gauge shows just less than 150 degrees.

Thank you all,

Bruce

[cdlaine]

Nomad...

Not sure if this is relevant... I own the truck in my sig. .
I went to the Allison manual for series 1000 transmissions.
Here is what the my manual indicates:

3.18 OPERATING TEMPERATURES
To properly operate the transmission, adhere to the following minimum
and maximum transmission operating temperatures:

Sump, minimum continuous 40°C (100°F)
Sump, maximum intermittent 121°C (250°F)
To cooler, maximum intermittent 149°C (300°F)

Your transmission may have a converter out
transmission temperature gauge near the “to cooler”
port on the transmission converter housing.

Charles

[gat75]

DW & I traveled 8000+ miles with our 2009 D/A 2500 little over a year ago. Pulled a 34' full profile Blue Ridge 5V. If I remember correctly, Truck & 5V weighed 19,300 on CAT scales.

The digital Tran temp climbed to 225 dgs while pulling steep grades on I-90 across Montana & upon west entrance of Yosemite. Ambient temp was still hot driving across I-90 in mid-September, (at least 95dgs during middle of day).

I chose to stop & allow rig to cool when it approached 225 dgs, (it seemed that the engine temp would likewise be around the same range).

Doing this gave a great piece of mind, (plus allowed DW & I to stretch & enjoy scenery).

I am sure that truck is probably designed to run hotter than my 225 max point, however, it is a known fact that the BIGGEST ENEMY OF TRANNYS IS HEAT.

[Old-Biscuit]

Where is that tranny temp being sensed??

Pan, return, cooler input etc.

Where it is sensed will have impact on what temp is 'normal'

On mine.....return line
Cool days---130*F/140*F routinely
Warm/hot days-----160*F/190*F
HOT days......180*F/200*F short excursions into 205*/210*F range (hard pull)