Let's try this tranny temp thing again

[MagikDraggin]

I read where heat is the #1 enemy of automatic transmissions. Yet I cannot get a straight answer as to how much heat is considered to be too much, or even what is considered to be "normal".

My temps have gone as high as 220 degrees from just a little "spirited" driving around. And then often times hang around the 200 mark or maybe 10 deg lower on a reasonably warm day, with just "normal" driving.

As a matter of fact, it seems as though the temps go up when I am actually driving, more than they do when I am sitting still for extended periods of time in heavy traffic with the tranny in drive.

Just where is the "break" point when the temp of the tranny is dangerous to its operation? The reason I'm asking is that I have a 2600 stall converter installed and am wondering if I NEED an aux cooler or not. Not "should" get one, but actually "NEED" one.

 

[Mad-Mic]

yes you "Need" one with a higher stall converter. they heat up the tranny fluid alot more than a stock stall. slippage in the converter adds friction to the fluid which adds extra heat.

where are you seeing your tranny temps? did you add a tranny temp gauge?

you are not looking at the engine oil temps are you? 180-230 is in the norm for oil temps

 

[MagikDraggin]

yes you "Need" one with a higher stall converter. they heat up the tranny fluid alot more than a stock stall. slippage in the converter adds friction to the fluid which adds extra heat.

where are you seeing your tranny temps? did you add a tranny temp gauge?

you are not looking at the engine oil temps are you? 180-230 is in the norm for oil temps

On my '96 one of the digital choices on the "gauges" button is one called "AUTO Temp". I am presuming that means Automatic transmission temp.

The other choices are oil temp, water temp, and alternator output.

Yes, I know that I should have a cooler, but I have heard they are so darned tough to find a place to install them without causing the radiator to start heating up more, that I was just trying to find out when too much heat is really TOO MUCH.

 

[Ken]

Automatic transmission fluid (ATF/Dexron) is designed to operate at high temperatures and under extreme hydraulic pressure. Normal operating temperatures are around 176° F (80° C). If the temperature should get much above 203° F (95° C), the life expectancy of the transmission fluid is almost halved.

The water in your radiator cools transmission fluid. If the water in the radiator is running very hot, then your transmission is also running hot. If your vehicle has a poorly maintained cooling system, and the water temperature gauge often gets up to the red zone, the chances are your automatic transmission will deteriorate that much quicker.

The fluid in your transmission should be bright red. As it deteriorates it turns a light brown with a hint of red. Any fine specks present in the fluid indicates a transmission overhaul is on the horizon, and changing the fluid at this stage is probably too late.

“Normal” operating temperatures are approximately 200° F. Someone here has actually seen a transmission on fire due to overheating! :eek

AMSOIL:

ATF is perhaps the most complex lubricant in existence.

 

[tntcorvette]

I have a tranny temp guage mounted on my pillar and the temp sensor is located in the "out" line from the tranny, which then goes to a B&M racing 28,000 GVW tranny cooler.

Lately it has been cool in Chicago and it takes awhile before the tranny temp moves past 150...usually about 10 minutes.

Definetly get one.

I had my tranny cooler mounted on the opposite side of the air filter but since I installed a TPIS cold air intake I had to to move it. It is now mounted on the a/c condensor.

I hope I do not have cooling issues next summer...but i'm still running the stock radiator and I have bypassed the radiator/tranny fluid cooler and just use the air to air cooler.

 

[MagikDraggin]

Normal operating temperatures are around 176° F (80° C). If the temperature should get much above 203° F (95° C), the life expectancy of the transmission fluid is almost halved.

“Normal” operating temperatures are approximately 200° F. Someone here has actually seen a transmission on fire due to overheating! CAC

Yes, I suppose I should pull the radiator and make certain everything is up to snuff. It only gets up there in temperature (around 230) when I run the A/C and lope around in town on a 90+ degree day.

When the tranny is reading 215, the water is at 195. I have a 160 Tstat and the fan temps altered to come on sooner, but even on a hot day, it's not really enough. Usually, the tranny reads around the 180 to 190 mark and the radiator about the same or maybe 10 deg cooler.

I wish I had looked at the tranny temps BEFORE I had the T/C installed for comparison. I wonder if changing to a synthetic fluid would do any good temperature tolerance wise?

 

[Ken]

... should pull the radiator and make certain everything is up to snuff.

You will be amazed at the amount of debris that collects between the radiator and the a/c condenser. It collects a LOT of stuff! :eek

Synthetic oils won't necessarily lower your operating temperatures, but they do withstand higher temperatures better than petroleum-based oil.

_ken

 

[Mad-Mic]

i run mobil 1 synthetic in my tranny.

i just put a tranny cooler in mine i just got to hook the lines up still. i just don't have any time to finish anything!

it's the biggest hayden tranny cooler they make

 

[MagikDraggin]

Ok, finished R&R'ing the radiator and cleaned the A/C condensor as well. Helped the coolant temps to run lower quite a bit, but no effect on the tranny temps. Coolant now runs 178 deg and the tranny went up to 209 in no time.

I see two potential spots to install a tranny cooler. One is directly in front of the A/C condenser and the other is in front of what looks like a power steering cooler mounted just before the front crossmember.

Which one would you people figure would be the best spot to choose?

And I know it is probably a really stooopid question, but I am presuming when I install an aux tranny cooler, I eliminate the lines that run to the radiator, right?

 

[Ken]

Here's where I placed my aftermarket oil cooler. Don't see why you can't do the same with a tranny cooler.

_ken

 

[MagikDraggin]

Yeah, that's kinda what I meant....right in front of the A/C condenser. Thanks for the cool pics too.

 

[MaineShark]

And I know it is probably a really stooopid question, but I am presuming when I install an aux tranny cooler, I eliminate the lines that run to the radiator, right?

You can go either way. "Divorcing" the tranny cooler from the radiator means than an overheating car can't influence the tranny fluid temp. But it also means that the fluid will take longer to warm up, in cold weather (may or may not be an issue).

Lastly, by eliminating some of the cooling capacity, there is a chance that your external cooling setup, alone, might not be able to handle the heat output of the tranny, particularly if you have a high-stall converter, and a small cooler.

Of course, you can always add a second cooler, if that happens, or re-plumb it to include the radiator cooler (as long as you close up the ends of the radiator fittings so that the insides stay clean).

I went with a very large external cooler, and no cooler in the radiator. If it's really a problem, I'll add a second cooler, since my radiator doesn't have a cooler.

Joe

 

[MagikDraggin]

Thanks Joe.....you brought up some points that I hadn't considered. I don't really seem to have a problem with the coolant system overheating......just that the tranny temps really start rising while driving....not at idle where I figured would be the most "friction" caused by a slipping 2600 stall converter.

Like yesterday for example, the coolant stayed at 178 degrees and after about 20 minutes of driving (at 35 - 50 mph) the tranny temp was up to 211 degrees. After I pulled into the garage and let it idle for a couple minutes, the tranny temp came down a few degrees.

I'll get an external cooler and install it in line between the radiator and the transmission so as to have the benefit of BOTH units aiding in the cooling.

NOW, the question is, do I have the ext cooler in line before the radiator, or after it?

 

[MaineShark]

After. That gives you the best possible efficiency, and keeps you from potentially re-heating the fluid (if your external cooler got it down to 150, say, then running it through a 180-degree radiator after that would actually heat it up, rather than cooling it down).

Joe