Transmission temps - with / without external cooler when towing

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footy14

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The reason for this post is to get some factual data from users regarding transmission temperatures with and without an external cooler installed.

The reason im asking, is because I recently purchased an off road tent trailer that im going to be towing this year. The trailer has a dry weight of 2800lbs and is equipped with electric brakes.

My 4runner is a 99 ltd, NO external trans cooler, airbags installed with 266k kms (165k miles). I still need to install a 7 way connector and electric brake controller.

I want to see some measured data comparing the temperature differences between towing with or without a tranny cooler. I'm still undecided whether or not I am going to install one. I have read up on tranny coolers, and the consensus from most people is 'just install it, you wont regret it'......but I have yet to come across a discussion, where actual facts and data have been compared.

I recently got the torque pro app (best $14 spent), and have been monitoring temps around town. The highest i have seen, is around 205 fahrenheit and that was unloaded with 1 passenger going up to the local ski hill.

So, does anyone have any measured data of their transmission temps. I want to compare with and without an external transmission cooler while towing.

Consider the following: what were you towing? (the weight), how many passengers and gear did you have in the truck? What were the ambient temperatures outside? Did you have to tow over any large passes?....etc.

I look forward to your responses, which will hopefully help me to make the decision on whether i install an aux cooler.
 
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I wasn't going to respond because I do not tow anything, but wanted to let you know here in 70+ degree winter in AZ, I'm getting about 150-165 degrees off my scanguage, unloaded, no passengers. 205 seems high.
 
Right now it's around -10F out, so my trans temps are in the 120's around town. On the highway in the 110's. Normal winter day, 140-160. Summer time i was in the 170-190 range.

It was 21 degrees and I was climbing through mountains, O/D locking and unlocking and even kicking down into third It got into the 180's. That was with 4 people, plus a ton of gear.

I'll be installing a cooler this summer for sure to prevent the milkshake.
 
I have a massive cooler.In 70* temps I am right about 120-140 In 100* heat daily i sit right around 150-160, up to 180 when towing around 2klbs. I have to really try to get mine hot.
 
For Canada get one that has a LPD (low pressure drop) in it (B&M 70264 or Tru Cool 4454), bypassing most of the cooler until about 170, then fully opening about 180.

In 90 degree temps, 60% humidity, towing 4500lbs with another person, 185F.

Mount the cooler in front of the fan and as close to the condenser as possible. Change the fan clutch if need be.
 
Great replies. Thanks. Does anyone have any comparisons without a trans cooler?

LittleCaeser, do you tow that 4500lbs up and over any passes? Or is it mainly flat?

Im thinking that I shouldnt have too many issues towing 3000lbs....until I get to some of the larger climbs here in BC....and then gearing down and slowing down will probably be a must to avoid burning up the ATF.
 
footy14 said:
Great replies. Thanks. Does anyone have any comparisons without a trans cooler?

LittleCaeser, do you tow that 4500lbs up and over any passes? Or is it mainly flat?

Im thinking that I shouldnt have too many issues towing 3000lbs....until I get to some of the larger climbs here in BC....and then gearing down and slowing down will probably be a must to avoid burning up the ATF.
Click to expand...

You may want to switch to full synthetic ATF, it can survive higher temps, where regular ATF will get destroyed.

There was a thread somewhere around here that said full syn will still be OK for a little while if your trans temp hit 300 and once regular ATF hits 2 hundred something, it's shot.
 
Mainly flat. It is a boat that I was towing. I have a Tundra now that works better in towing it.

If the ATF has not been changed in some time, a drain and fill of some new fluid would be good. A complete flush would be better.

Something else to consider would be the Tundra upgrade, depending on what rims you have.
 
Can anyone answer this please ? Does a 4runner really need a tranny cooler ? Has anyone actually messed the tranny up from towing ? Has there actually been evidence that it helps ? Evidence about the milkshake looking oil ? Because one of my friends said its a waist of money.
 
footy14 said:
The reason for this post is to get some factual data from users regarding transmission temperatures with and without an external cooler installed.

The reason im asking, is because I recently purchased an off road tent trailer that im going to be towing this year. The trailer has a dry weight of 2800lbs and is equipped with electric brakes.

My 4runner is a 99 ltd, NO external trans cooler, airbags installed with 266k kms (165k miles). I still need to install a 7 way connector and electric brake controller.

I want to see some measured data comparing the temperature differences between towing with or without a tranny cooler. I'm still undecided whether or not I am going to install one. I have read up on tranny coolers, and the consensus from most people is 'just install it, you wont regret it'......but I have yet to come across a discussion, where actual facts and data have been compared.

I recently got the torque pro app (best $14 spent), and have been monitoring temps around town. The highest i have seen, is around 205 fahrenheit and that was unloaded with 1 passenger going up to the local ski hill.

So, does anyone have any measured data of their transmission temps. I want to compare with and without an external transmission cooler while towing.

Consider the following: what were you towing? (the weight), how many passengers and gear did you have in the truck? What were the ambient temperatures outside? Did you have to tow over any large passes?....etc.

I look forward to your responses, which will hopefully help me to make the decision on whether i install an aux cooler.
Click to expand...

OP, I have the Engine Link app on my iPhone, and have just started monitoring transmission temps on my '99 Limited as well. I've had my stock (in the radiator) trans cooler bypassed, and am only using the B&M external cooler to cool the transmission fluid. I never got to monitor temps before I bypassed the radiator (and I have no intention of going back, risking a pink milkshake), but I'll post relevant data when I can.

For now, I've only used my 4Runner to go back and forth to work... Which for me, is a five minute drive on city streets. With the radiator trans cooler bypassed, and only using the external, my transmission is slow to warm up. Ambient temperature lately has been in the 40's, and the max temp I'll see for my trans fluid is about 120 degrees. This is just city driving. I'll post up more findings as they come.

kolelt said:
Can anyone answer this please ? Does a 4runner really need a tranny cooler ? Has anyone actually messed the tranny up from towing ? Has there actually been evidence that it helps ? Evidence about the milkshake looking oil ? Because one of my friends said its a waist of money.
Click to expand...

I don't think it's a waste of money. Search for "pink milkshake" and you'll find all the evidence you need.
 
Typical readings when driving casually around town.

vy4uha9e.jpg
 
I have the torque pro app. My trans temp readings seemed to run a little higher as well for no reason. I will plug it in tomorrow and report back.

Before you go adding a trans cooler, consider that the torque app may be incorrect. I don't know how it would be but it might be better to rule that out first.

Anyone else using torque pro?
 
I used torque for a while, but never monitored trans temps with it.

I think the "error" is because the sensor for trans temp is in or near the pan, so it is hotter than if you measure with a real gauge at the cooler or along the intake line from the cooler.
 
kernel.panik said:
I used torque for a while, but never monitored trans temps with it.

I think the "error" is because the sensor for trans temp is in or near the pan, so it is hotter than if you measure with a real gauge at the cooler or along the intake line from the cooler.
Click to expand...

Regardless, if we're all taking temps at the same location, we should all have a pretty good idea if we're running hot / cold / normal relative to each other.
 
kolelt said:
Can anyone answer this please ? Does a 4runner really need a tranny cooler ? Has anyone actually messed the tranny up from towing ? Has there actually been evidence that it helps ? Evidence about the milkshake looking oil ? Because one of my friends said its a waist of money.
Click to expand...

Still seems like we havent answered the initial question. Does anyone else have any input regarding towing with or without a tranny cooler.......and I'm not looking for the "just install it...it's cheap insurance" answer, which seems to be a common reply.

I'm more concerned about the facts.

Anyone have experience towing without an external transmission cooler?
 
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