TH400 Temperature

[cjkeeliii]

Does anyone know the TH400's proper operating temperature?

 

[Stonepicker1]

Don't know if this is correct but I did a "google search" and got this info from "rv.net"

Here is a quote from the Orange ($8.95) GM manual:
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"OIL TEMPERATURE MEASURED AT CONVERTER OUTLET TO COOLER.

300F is the maximum temperature. (Workhorse says 350F). This is the normal place to install a temperature gauge or signal. The temperature in this location will vary significantly with each vehicle start-up or hill. If the temperature reaches 300F (350F), reduce throttle. To lower the transmission temperature with the transmission in NEUTRAL, run the engine at 1,200 RPM for 2-3 minutes to cool the oil. Do not allow the converter outlet temperature to exceed 300F (350F).
Keep a close check to prevent the engine cooling system from overheating.

300F would be typical of rocking the vehicle in mud, snow, or sand, or a transmission in stall (full throttle, no vehicle movement). When the transmission is in stall, the transmission will develop heat at a rate of one degree per second of stall.

OIL TEMPERATURES MEASURED IN THE SUMP

150F -- Minimum operating temperature for continuous operation. It is possible in low ambient temperature to overcool the transmission with oil to air-type coolers; it is hard to overcool if used in conjunction with oil to water coolers installed in most standard automotive [COLOR=#0072bc !important][COLOR=#0072bc !important]radiators[/COLOR][/COLOR].

190F-200F -- Maximum oil level checking temperature. Beyond this, readings are not reliable because of expansion.

285F -- Maximum sump/oil pan temperatures for short duration such as a long hill climb.

300F -- Metal parts inside the transmission begin to warp and distort in varying degrees, seals melt rapidly, and transmission fluid life is extremely short due to oxidation and distress.

AUTOMATIC TRANSMISSION FLUID OXIDATION Automatic transmission fluid
can provide up to 100,000 miles of service before oxidation occurs under normal operating temperatures of about 170F. Above normal operating temperatures, the oxidation rate doubles (useful life of the fluid is cut in half) with each 20 degree increase in temperature. The approximate life expectancy at various temperatures is a follows:
Degrees F Miles
175 100,000
195 50,000
212 25,000
235 12,000
255 6,000
275 3,000
295 1,500
315 750
335 325
375 80
390 40
415 Less than 30 minutes

After-market temp gauge should be installed in the lower (hot) line entering the lower fitting of the radiator.

After-market external oil to air cooler should be installed in series. The hot oil line should go first through the aftermarket cooler then into the radiator to maintain proper minimum temp of the trans in low ambient temps.”

End of GM copy from orange manual.
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Note: Later (green) manual says run through radiator heat exchanger first. Don't know why they changed.

My take on this: A converter outlet reading should give the first indication of heat increase. It also lets you know if you are near maximum fluid temp of 300 (or 350 in Workhorse manual). Another reason I like converter out temp is it gives you not only info to save your tranny, but it also tells you how much heat your are putting into your radiator, thereby allowing you to perhaps avoid an engine overheat by shutting off dash air or whatever else you do. Having a pan temp reading allows you to be sure you don't exceed max pan temp of 285F for the TH400 and lets you know if your cooler is big enough for the hill you just climbed. Once you have climbed your biggest hill on your hottest day without an overtemp event, you can forget about watching the tranny temp.

 

[1986Blazerk5]

Thats interesting i think i might install a trans temp gauge, anybody know where to buy one?

 

[319]

Thats interesting i think i might install a trans temp gauge, anybody know where to buy one?

Auto parts store

 

[Westech]

Yeah where dose one find "fuel" for this so called "cucv thing" and where do you get air fresheners? Is there a place where I can get food and loto tickets?

You know some days you guys make me want to

 

[frodobaggins]

No reason to be rude.

 

[cjkeeliii]

Thanks Stonepicker1. Lot of useful info in that post.

 

[cjkeeliii]

1986blazerk5 I'm going to use the same kind of temp setup that I have for the radiator. Seems to me that it'll work for tranny fluid just as well as for antifreeze.

 

[OL AG '89]

300 degrees.... that seems REALLY HOT!!!!
I have a GMC 3500 and it runs at about 175 - 190 depending on load or speed...

I am curious anybody got "proof" of the 300 on a temp gauge.....

 

[1986Blazerk5]

300 degrees.... that seems REALLY HOT!!!!
I have a GMC 3500 and it runs at about 175 - 190 depending on load or speed...

I am curious anybody got "proof" of the 300 on a temp gauge.....

All the trans temp gauge's i have seen only go up to 250 degrees

 

[OL AG '89]

86 you're not looking hard enough here's one from Summit racing.........

 

[biggestc69]

I have my temp sender in the pressure port on the drivers side of the transmission. Is that a good indication of how hot the fluid is before it goes to my aftermarket cooler? I just went ahead and bypassed the factory radiator one. I have an Autometer Trans temp gauge that goes to 250 I think, not very high but this last weekend I had to bust some drifts to get a buddy out and the drifts were frozen. Long story short I would have to build up a run, hit it and then reverse out, not really rocking it because it was never stuck it just wouldnt push anymore but it always reversed out no problem. By the time I got around them the tranny temp was up to a little over 210, highest its every been. Even when towing trailers in 100+ degree temps this summer. Stop and go traffic only got it up to 190. So basically my question is the location of my sending unit for the gauge giving me the max heat the tranny is at on its way to the cooler? And is that a good place to put it, personally I would lik to know how hot it is at its hottest point, but maybe someone else has a different opinion or view they could school me on?

 

[MarcusOReallyus]

After-market external oil to air cooler should be installed in series. The hot oil line should go first through the aftermarket cooler then into the radiator to maintain proper minimum temp of the trans in low ambient temps.”

End of GM copy from orange manual.
------------------------------------------------------------------
Note: Later (green) manual says run through radiator heat exchanger first. Don't know why they changed.

The first info agrees with what I was told on another forum by a trans rebuilder (or at least someone who plays one on the Internet). The idea is to dump the majority of the heat BEFORE it gets to your radiator, THEN run through the radiator to make sure it didn't get TOO cool.

Makes sense to me. If you are working the machine extra hard, why would you want to dump transmission heat into your engine coolant? By going through the external cooler FIRST, you are dumping that heat outside of the engine cooling system, instead of dumping it INTO the engine cooling system.

 

[cliffyp]

Here's some speculation:

Considering varying engine temps in different applications, perhaps when the trans oil goes through the radiator second it can return to the trans hotter than the desired 170ish because it picked up too much engine heat in the radiator.

For example, lets say the vehicle has a 200 engine operating temp. The trans fluid gets staged down. High temp down to 200 ish then from there down to 170. Perhaps in an excessive trans heat situation an aftermarket cooler ahead of the radiator isn't able to throw off enough heat. Say it leaves the cooler at 230 and goes to the radiator where it only comes down to 190.

Just guessing, I have know basis to this thought process.