Automatic Transmisison Temperature

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,128
Reaction score
9,299
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
Here is a Trans Temp Chart that makes understanding of how heat shortens trans life very easy.

attachment.php
 

Attachments

  • transheat.jpg
    transheat.jpg
    79.1 KB · Views: 994

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,128
Reaction score
9,299
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
Whenever possible, if you choose to add a transmission cooler, its highly recommended that you DO NOT bypass your radiator cooler to use an aftermarket cooler. Bare in mind, using your radiator trans cooler is dual purpose. It will also warm your transmisison fluid quicker in cold winter months. Cold thicker trans fluid can actually do as much damage as to much heat. Here is a diagram of how the ideal trans cooling system with an added cooler should be installed.

attachment.php


Out of the feed line of the transmisison, into the radiator cooler.
Out of the radiator cooler, into the aftermarket cooler.
Our of the added fin type/air cooler and return to the transmisison.

You must be registered for see images attach
 
Last edited:

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
30,446
Reaction score
28,349
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
What about intermittent spikes in temp? Will that really hurt it in the long run?
 

Old77

Administrator
Staff member
Admin
Joined
Aug 19, 2010
Posts
28,456
Reaction score
9,431
Location
Kansas City, Mo
First Name
Jacob
Truck Year
1977/1990/1991
Truck Model
C10 longbed/R1500 Burb/R3500 Dually
Engine Size
350/350/454
So who needs a trans cooler and who doesn't?
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,128
Reaction score
9,299
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
Short term spikes are expected for certain situaitions, like towing a heavy trailer and climbing a grade, or your truck is stuck and you are rocking it to get out of a mud hole etc. You certainly want to minimize the spikes to be as short as possible. Its best to add a cooler if you have reasons to have spikes quite often.
A good example of that, I had a buddy that would make a trip to the dump probably 3 times a week to dump a trailer load of roofing material. And to go to the dump, he was climbing probably 4 miles of steep hill to get to the dump site. Doing that 3x week probably pulling 6000lb of trailer and roofing up hill. I told him to add the biggest cooler that he could reasonably fit in front of his radiator. I also told him to change his fluid and filter about every 30,000 miles instead of what I'd normally reccomend of 50,000 miles for average daily driver.
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,128
Reaction score
9,299
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
So who needs a trans cooler and who doesn't?

Anyone who is towing should have a trans cooler period !!! If you frequently carry heavy loads in your truck, if you offroad, as in wheeling, or muddin, you for sure need a trans cooler. Any type of abuse you put a vehicle through, should have a cooler. Also, even to add a small cooler just because isn't a bad idea regardless of the abuse. The cooler the trans, the longer it lasts.
 

89Suburban

Supporting Member
Supporting Member
Joined
Dec 7, 2010
Posts
24,772
Reaction score
6,637
Location
Southeast PA
First Name
Paw Paw
Truck Year
2007
Truck Model
Chevrolet Tahoe LT
Engine Size
5.3, 4WD
Awesome animations dude!!!! :High 5:
 

austinado16

Full Access Member
Joined
May 25, 2012
Posts
611
Reaction score
222
Location
Central Coast, CA
First Name
Todd
Truck Year
1990 w/307k miles on the clock
Truck Model
GMC V1500 Suburban SLE
Engine Size
5.7L TBI/4L60/3.42's
Here's a few shots of how I keep mine cool. This is the 11x11x1.5" Tru-Cool, which is the same as the B&M Super Cooler, just reboxed. Remember, if you had a cooler, the fittings can not be facing downward as you can see in a couple of my photos. With the fittings facing down, an air bubble will form inside the cooler and the ATF will bypass the entire cooler by just going through the first 2 rows.

Additionally, I replaced my transmission pan with the B&M cast aluminum pan that holds an additional 3.5qts. I have a mechanical temp gauge bunged into the pan.
You must be registered for see images attach


You must be registered for see images attach


You must be registered for see images attach


You must be registered for see images attach
 

austinado16

Full Access Member
Joined
May 25, 2012
Posts
611
Reaction score
222
Location
Central Coast, CA
First Name
Todd
Truck Year
1990 w/307k miles on the clock
Truck Model
GMC V1500 Suburban SLE
Engine Size
5.7L TBI/4L60/3.42's
You must be registered for see images attach


How do you feel that performs? I've always heard that the stacked plate design, like the ones in my photo (the one on the driver's side is the factory engine oil cooler) are more efficient.
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,128
Reaction score
9,299
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
I've been told, and it seems to make sense to me, that the stacked ones like the OEM coolers work best for dropping the temp, but they cool much less fluid. The ones like the aftermarket one you posted just above this post, work well and drop the fluid a few degrees but they also cool a much larger volume of fluid because the tubes are much bigger and circulate more fluid quicker. I guess the only way to really know is to try both using Temp gauge and see for ourselves.
 

gpmorgan

Full Access Member
Joined
Nov 9, 2013
Posts
562
Reaction score
105
Location
Tupelo Ms.
First Name
greg
Truck Year
1992
Truck Model
1500
Engine Size
632
How do you feel that performs? I've always heard that the stacked plate design, like the ones in my photo (the one on the driver's side is the factory engine oil cooler) are more efficient.[/QUOTE]



While the one you have probably works better, I'm sure the one I have has to have some cooling ability.(10 1/2 x 21 x 1 !/2) It's marketed as an oil cooler and I've seen this type on numerous applications.
 
Last edited:

Sublime

Full Access Member
Joined
Oct 7, 2016
Posts
169
Reaction score
60
Location
usa
First Name
m
Truck Year
1978
Truck Model
k10
Engine Size
350
I am adding an aux transmission cooler. I have a TH350. The instructions state to route the hot transmission fluid line to the radiator cooler, then to the aux. cooler, back to the transmission. There are two ports on the transmission, one above the other. My question is which port on the transmission is the "pump / hot" and which is the return/cool port? My research found a 50/50 split. Currently I have the trans pan down and the torque converter is out. I am also replacing the trans cooling lines from the trans to radiator so I decided to blow thru them from the radiator end to remove any remaining trans fluid from them. The lines were still connected to the transmission. Nothing came out of the top port but fluid came out of the input shaft (converter shaft) when blowing thru the bottom port. Can i assume the bottom port is connected directly to the pump and the pump is feeding the hot fluid to the cooler? Or is the returning "cooler" fluid going to the pump (this does not sound logical)?
And while we are on the subject, should the hot fluid from the trans go to the top of the radiator cooler or bottom - does it even matter?
Thanks much
 

77 K20

Full Access Member
Joined
Nov 9, 2012
Posts
3,101
Reaction score
3,119
Location
Montana
First Name
Mike
Truck Year
1977
Truck Model
K20 5" lift
Engine Size
HT383 fuel injected
I've always read and heard that if you live in a cold climate route from the transmission to the aux cooler then through the radiator cooler. Why? In winter when it is very cold the ATF will go thru the aux cooler, get colder but then "warm" up a bit in the radiator before going into the transmission.
Summer time the aux cooler will still do a majority of the cooling and then the radiator cooler will not do much to change it one way of another. (My thermostat/radiator runs at 180*).
 

mtnmankev

Full Access Member
Joined
Jun 10, 2014
Posts
1,623
Reaction score
3,293
Location
Ash Fork, Arizona
First Name
Kevin
Truck Year
1984, 1983
Truck Model
K10, C20
Engine Size
383 Stroker, 350
I am adding an aux transmission cooler. I have a TH350. The instructions state to route the hot transmission fluid line to the radiator cooler, then to the aux. cooler, back to the transmission. There are two ports on the transmission, one above the other. My question is which port on the transmission is the "pump / hot" and which is the return/cool port? My research found a 50/50 split. Currently I have the trans pan down and the torque converter is out. I am also replacing the trans cooling lines from the trans to radiator so I decided to blow thru them from the radiator end to remove any remaining trans fluid from them. The lines were still connected to the transmission. Nothing came out of the top port but fluid came out of the input shaft (converter shaft) when blowing thru the bottom port. Can i assume the bottom port is connected directly to the pump and the pump is feeding the hot fluid to the cooler? Or is the returning "cooler" fluid going to the pump (this does not sound logical)?
And while we are on the subject, should the hot fluid from the trans go to the top of the radiator cooler or bottom - does it even matter?
Thanks much

I too am curious as to which port in the radiator should get the fluid from the hot side.
It would seem logical to me to have the flow from top to bottom, as the radiator coolant is "colder" towards the bottom instead of pumping the ATF in at the bottom only to retain as much heat as possible before it exits.

As to which line from the trans is hot, that should be easy to figure out, disconnect both lines at the radiator/cooler, and have an assistant start the engine for a brief second and watch to see which line has pressure shooting out.
Unless I am wrong .........
 

Forum statistics

Threads
44,173
Posts
950,832
Members
36,287
Latest member
goodwrenchca
Top