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Tranny Temp with a cooler?

2K views 19 replies 6 participants last post by  Deuce 
#1 ·
Anyone with a 1/2ton truck running a stand alone tranny cooler without the lines going thru the radiator and have a temp gauge to monitor the temp? If so, what what's the hotest does it get? If you've towed a boat or travel trailer, how hot does it get? I'm just figuring out if I'll need to run a fan on the cooler or not on the 4l60e tranny behind the 5.3 Vortec engine in the '56 Burb :confused: .
 
#2 ·
Use a cooler rated at 18000 GVW or higher and you will be fine. The trans will be happy for a long time running between 180-220 degrees. If you use a temp gauge, mount sender in the pan, not in a cooler line or pressure fitting hole. Make sure the torque converter clutch operates correctly or NO cooler will help. If you are towing, the bigger the cooler the better (24000-30000 GVW). I use coolers manufactured by Long out of Canada ( factory equipment) sold under the trade name Tru-Cool at my shop. Also, take the time to mount the cooler in front of the radiator about 1/2" to 1" away. Those Zip tie do-dads smash the radiator and cooler together and actually cause airflow problems thru both!
 
#3 ·
Chazmac said:
Use a cooler rated at 18000 GVW or higher and you will be fine. The trans will be happy for a long time running between 180-220 degrees. If you use a temp gauge, mount sender in the pan, not in a cooler line or pressure fitting hole. Make sure the torque converter clutch operates correctly or NO cooler will help. If you are towing, the bigger the cooler the better (24000-30000 GVW). I use coolers manufactured by Long out of Canada ( factory equipment) sold under the trade name Tru-Cool at my shop. Also, take the time to mount the cooler in front of the radiator about 1/2" to 1" away. Those Zip tie do-dads smash the radiator and cooler together and actually cause airflow problems thru both!
Would it not be alright to mount the temp sender at the transmission in the output line?
 
#5 ·
It is my opinion, that the temperature you are most concerned with is the oil temp leaving the transmission bound for the cooler. The first indication of transmission overheating will show up there first. Fluid in the pan will be much cooler. Lubricating oil breakdown is the reason most transmissions fail. Watch the oil temp coming from the trans and try to keep it below 240 degrees. IIRC most trans fluids will start to break down around 260 degrees. I think I got those numbers from a B&M rep several years ago. The reason most folks put the thermocouple in the pan is ease of installation, and that includes me.

Merry Christmas!
 
#6 ·
Overdriv said:
It is my opinion, that the temperature you are most concerned with is the oil temp leaving the transmission bound for the cooler. The first indication of transmission overheating will show up there first. Fluid in the pan will be much cooler. Lubricating oil breakdown is the reason most transmissions fail. Watch the oil temp coming from the trans and try to keep it below 240 degrees. IIRC most trans fluids will start to break down around 260 degrees. I think I got those numbers from a B&M rep several years ago. The reason most folks put the thermocouple in the pan is ease of installation, and that includes me.

Merry Christmas!

Right, I agree, That is what I said = quote "Would it not be alright to mount the temp sender at the transmission in the output line?"

Looks to me that is the hottest spot.... At least that is where I have always mounted the temperature sensor.

I have gotten marvelous service from Mobil 1 ATF.
 
#7 ·
Chazmac said:
Make sure the torque converter clutch operates correctly or NO cooler will help. !
Excuse me, you weren't clear......

are you saying that transmissions will burn up if you are NOT driving in lock-up ? or if you ARE driving in lock-up ??

There were no such things as lock-up converters for 20 years, and even today many are eliminating them.....

????????????????
 
#8 ·
Overdriv said:
It is my opinion, that the temperature you are most concerned with is the oil temp leaving the transmission bound for the cooler. The first indication of transmission overheating will show up there first. Fluid in the pan will be much cooler. Lubricating oil breakdown is the reason most transmissions fail. Watch the oil temp coming from the trans and try to keep it below 240 degrees. IIRC most trans fluids will start to break down around 260 degrees. I think I got those numbers from a B&M rep several years ago. The reason most folks put the thermocouple in the pan is ease of installation, and that includes me.

Merry Christmas!

I am glad you have the opinion, although my 3 decades of tranny experience tells me you are incorrect..

The problem is the oil coming out of the tranny is from the converter and will give a false high temp reading. The oil is not at that temp long enough to damage the oil.

The oil returning from the cooler to the tranny goes into the lube circuit. This oil lubes and removes heat from the internal tranny parts, then the oil falls into the pan for reuse.

that is where the temp reading needs to be taken from since it has removed the heat from the internal parts and remains at this temp for long periods of driving which can break down the oil IF the temp is too high.

:cool:
 
#10 ·
I am not a trans guy so maybe you guys can help me.

If high stall or loaded converters are what cause most of the heat problems, why do you NOT measure the point of highest temperature coming out of the transmission?

Are you saying that the pan temp needs to be at least 212* to evaporate the condensation in the oil, and beyond that point (212* F) shouldn't a trans run as cool as possible ??

And this also. I have asked this 3 times on this site and I have even written some car mags and asked...and never gotten an answer.
Why do people measure engine oil temperature at the coldest point rather than the hottest point in the system?? People seem to insist that the temp must be measured at the INPUT to the engine AFTER the aux. cooler or after the filter at the oil pressure hole...... How do you know how hot it really is?? There have been mag articles about this.

I don't get it?

Thanks for helping me understand.
 
#11 ·
xntrik said:
I am not a trans guy so maybe you guys can help me.

If high stall or loaded converters are what cause most of the heat problems, why do you NOT measure the point of highest temperature coming out of the transmission?

Are you saying that the pan temp needs to be at least 212* to evaporate the condensation in the oil, and beyond that point (212* F) shouldn't a trans run as cool as possible ??

And this also. I have asked this 3 times on this site and I have even written some car mags and asked...and never gotten an answer.
Why do people measure engine oil temperature at the coldest point rather than the hottest point in the system?? People seem to insist that the temp must be measured at the INPUT to the engine AFTER the aux. cooler or after the filter at the oil pressure hole...... How do you know how hot it really is?? There have been mag articles about this.

I don't get it?

Thanks for helping me understand.
1. I explained why the tranny oil temp is taken at the pan ( previous post) , not the fluid temperature out of the converter. Some drag race cars do not run coolers, they run a loop or tube connecting the ports on the tranny case.

2. Trans oil does not need to be 212*F to evaporate moisture from the oil. Water boils at 212*F, it evaporates at lower temps. Tranny oil in the area of 150 - 180*F is fine for moisture removal and operation of the trans

3. Ask the engine oil temp questions in the engine section of this board
 
#12 ·
Crosley said:
I am glad you have the opinion, although my 3 decades of tranny experience tells me you are incorrect..

The problem is the oil coming out of the tranny is from the converter and will give a false high temp reading. The oil is not at that temp long enough to damage the oil.

The oil returning from the cooler to the tranny goes into the lube circuit. This oil lubes and removes heat from the internal tranny parts, then the oil falls into the pan for reuse.

that is where the temp reading needs to be taken from since it has removed the heat from the internal parts and remains at this temp for long periods of driving which can break down the oil IF the temp is too high.

:cool:

I have been around automatic transmissions since the late 60s and have witnessed the effects of overheated trans fluid. My experience is mainly with 4 wheel drive trucks for play and farm trucks for work. If you are consistantly working your fluid above 250 degrees it will breakdown soon. When you see a steady 250 degrees in the pan, it's probably to late. It's the breakdown of the fluid, the loss of lubrication, that does the most damage, not neccessarily the temp of the parts.

The pan is the easy place to monitor fluid temp, not the best place. It's certainly better to monitor it there as oposed to not at all.
 
#13 ·
Overdriv said:
I have been around automatic transmissions since the late 60s and have witnessed the effects of overheated trans fluid. My experience is mainly with 4 wheel drive trucks for play and farm trucks for work. If you are consistantly working your fluid above 250 degrees it will breakdown soon. When you see a steady 250 degrees in the pan, it's probably to late. It's the breakdown of the fluid, the loss of lubrication, that does the most damage, not neccessarily the temp of the parts.

The pan is the easy place to monitor fluid temp, not the best place. It's certainly better to monitor it there as oposed to not at all.
The rise in oil temp is seen quickly in the trans pan. I test trannys on dynos every day at my work place.

have you tested oil coolers for oil temps before the oil enters and after the cooler? You would be surprised by the results if you have not.
 
#14 ·
Crosley said:
The rise in oil temp is seen quickly in the trans pan. I test trannys on dynos every day at my work place.

have you tested oil coolers for oil temps before the oil enters and after the cooler? You would be surprised by the results if you have not.
Crosley, I bow to you as the expert, and value your participation on this site. On this though, I will have to disaggree. I am not trying to change your mind or anyone elses. I have not dynoed anything. My only experience is through real world applications, 4X4 pickups in the mudpit, 4X4 pickups pulling 250-300 bushel gravity flow wagons, ETC. I have indeed watched the temp rise in the pan and the line to the cooler, but never at the same time. I have found that if you keep the fluid to the cooler below 260 degrees, the trans fluid will survive most anything, day in and day out, and usually if the fluid does not breakdown the trans will survive, temp wise anyway.

Merry Christmas!
 
#15 ·
Overdriv said:
Crosley, I bow to you as the expert, and value your participation on this site. On this though, I will have to disaggree. I am not trying to change your mind or anyone elses. I have not dynoed anything. My only experience is through real world applications, 4X4 pickups in the mudpit, 4X4 pickups pulling 250-300 bushel gravity flow wagons, ETC. I have indeed watched the temp rise in the pan and the line to the cooler, but never at the same time. I have found that if you keep the fluid to the cooler below 260 degrees, the trans fluid will survive most anything, day in and day out, and usually if the fluid does not breakdown the trans will survive, temp wise anyway.

Merry Christmas!
I do not think I am expert. I've just banged my head on the work bench with these trannys more than some.

I am posting the same thing you are posting , real world things I have seen happen and testing that I have performed.

I just happen to work on these auto trannys for a living...... less than 8 years till retirement. :thumbup:
 
#17 · (Edited)
Chazmac said:
I am continually stumped by how many of you will not listen to those who know of what they speak and do this for a living....
We ARE here to help, not fight. Sometimes this gets to be too much...
Remember the boy who cried wolf?
Chazmac, I really don't know what you are talking about?? I really don't think we are fighting???

Just because someone has done something one way for 30 years does not make it the only way to do it. Sensing the trans temp in the pan is the easiest place to do it. And I stated that I have and continue to sense it there also. But when I have had the chance to sample the fluid temp in the hot line to the cooler, I found it to be a better indication of the real temp the oil was being worked at. And that is the most important piece of information to have, the temperature at which the oil is being worked. If that temp is so high as to cause the oil to oxidize it will begin to loose it's lubricating properties. I think it's clear what happens then.

I am certainly not an expert like Crosley. I have not worked on them for a living for 20 years. But I have stayed active and done a few from time to time. One thing I have learned over the years is there are always new ways to do things, some better, some not. Having an open mind to analyze a new procedure or idea is very important.

In the mid to late 60s, I wouldn't have given you a nickel for a powerglide transmission. They had a very high failure rate. And it was caused by high temp more times than not. About 5-6 years ago a friends son came to me and wanted me to build a powerglide for his race Vega. Of course I was aware of the racing being done with the PGs and aggreed to do it so I could see what it would take to build a good PG. He raced with it for two seasons and in the third race of the third season it finally gave up, 330 runs later. That PG had all stock parts except for the band, a hardened input shaft, the converter, and a Coan brake & valve body. I was amazed it lasted that long.

Lighten up guys, there is a lot I don't know but that does not make me inexperienced. I'm here to learn and contribute if that's ok?

BTW, Crosley, I'll start my retirement in 7 years if all goes as planned.

This is a great BB!
Merry Christmas to you all.
 
#19 ·
I do not think there was a p--ing match here.

Overdrv is posting his experience..... I posted mine.

The reason I do not suggest the "out line" from the tranny for temps is the false 'high ' reading and the fact I delt with a customer 20+ years on a C-6 with this.

He called me about "high temps" from his tranny guage. He had a cooler , even added a second with a fan. After a couple of weeks of calls, his fluid was still red , yet still operating at a high temp.

When I saw the car in person his temp probe was on the "out line" of the tranny. The car is ( he still owns it) a Ford Torino with a 351C and C-6. This car has a factory hi-stall converter and the car ran like stink bone stock.

After the temp probe was moved to the pan , the operating temps were at 160 to 180...... not the 220 - 240 range.

Second eggzample:

A customer had a turbo diesel Ford truck. He installed one of our towing converter . He calls real upset that the tranny is running 'hotter' now....... after an investigation of the vehicle we find he had changed the converter AND moved his temp probe to the ' cooler out line' from the tranny pan. After the temp probe was moved back to the pan the tranny was shown to be operating in a normal temp range
 
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