Chevy & GMC Vans

LiftedAWDAstro wrote: Now for some aux cooler tests. The test was done on the 2003 AWD and was done when we drove it to trade in on our truck. The tranny was in perfect shape...new Amsoil synthetic fluid and filter, Transgo HD-2 shift kit and Corvette servo. There was NO slip in the tranny!!!! The day was in the mid 70's and wasn't too humid out. With the aux tranny cooler installed the tranny temp would never get above about 150 - 165 no matter where we drove or how fast. This is without towing. The day we traded the van in, I removed the aux cooler and on the drive to get the truck, the tranny easily reached the 180 degree mark within about 10 miles of driving. This was from a cold start! The final temp once we arrived at the dealer (40 mile drive, mostly interstate) was around the coolant temp of 195! This is a 30 to 45 degree difference with just the aux cooler plumbed after the stock cooler. No wonder we would see 210 towing our camper and that was babying it. I can't even imagine how hot the tranny would get with no aux cooler! My final suggestion for long tranny life is synthetic fluid and a massive tranny cooler!

Thanks for that comparative info Dean, those are BIG differences showing the effectiveness of the aux cooler.

LiftedAWDAstro wrote:
Now for some aux cooler tests. The test was done on the 2003 AWD and was done when we drove it to trade in on our truck. The tranny was in perfect shape...new Amsoil synthetic fluid and filter, Transgo HD-2 shift kit and Corvette servo. There was NO slip in the tranny!!!! The day was in the mid 70's and wasn't too humid out. With the aux tranny cooler installed the tranny temp would never get above about 150 - 165 no matter where we drove or how fast. This is without towing. The day we traded the van in, I removed the aux cooler and on the drive to get the truck, the tranny easily reached the 180 degree mark within about 10 miles of driving. This was from a cold start! The final temp once we arrived at the dealer (40 mile drive, mostly interstate) was around the coolant temp of 195! This is a 30 to 45 degree difference with just the aux cooler plumbed after the stock cooler. No wonder we would see 210 towing our camper and that was babying it. I can't even imagine how hot the tranny would get with no aux cooler! My final suggestion for long tranny life is synthetic fluid and a massive tranny cooler!


Thanks for that comparative info Dean, those are BIG differences showing the effectiveness of the aux cooler.

Good stuff. Has there ever been a comparason using the aux. cooler ONLY, compared to aux cooler and rad. tranny cooler working together ? Think this is something I had planned to do and psot but never got around to getting the info.

But even though the transmission temperature gauge doesn't get over 100F, the shifting becomes normal after a few blocks of driving.

Is this still the case Rob and this is running aux. cooler only,,correct ??

There are plate coolers that have a built-in temp regulator.
At low temps, the fluid bypasses most of the plates.
At higher temps the fluid passes thru all plates.

Rebel wrote:

But even though the transmission temperature gauge doesn't get over 100F, the shifting becomes normal after a few blocks of driving.

Is this still the case Rob and this is running aux. cooler only,,correct ??

No, I'm presently running the aftermarket cooler plumbed in before the radiator. When I first installed the cooler, I had it running alone; I didn't plumb in the radiator. This was with the first transmission I had in my 89 and it had slippage problems. I had installed a transmission temperature gauge and freaked out when I saw how hot the ATF was getting--the gauge was pegged at max after a little in-town driving on a hot day. I immediately added the transmission cooler. I bought one for an RV, the biggest cooler I could find. Like I mentioned, I originally just had the transmission connected to it, no path through the radiator at all. That really helped, at least the temperature gauge was pegged, but it was close. So I then added the radiator back into the ATF circuit in the form of transmission--aux cooler--radiator cooler--back to transmission. That got the temperatures down some more, at least I wasn't scared anymore to look at the temperature gauge.
But the real answer was to install a better functioning transmission, which I did. I left the cooler plumbing as I had it for the old transmission. With the rebuilt transmission, I rarely ever see the transmission temperature go above 165F in the summer. But, when I installed the transmission, I also added a B&M deep transmission pan that adds an extra 3 quarts of ATF. Extra capacity has got to help some when it comes to temperatures, but I don't know how much. So I have to think that the aux cooler is what's really doing the job.

I'm not done experimenting with cooling the transmission yet. I still want to see how the transmission does without the radiator in the circuit; I just don't think that the radiator should have to deal with the heat from the transmission. No science to back that up, though, just a personal preference.

By the way, when I initially installed the transmission temperature gauge I used two sensors; one was teed into the output transmission line while the other was teed into the input line. I used a SPDT toggle switch to select which sensor the gauge was connected to. My intention was to see just how much heat was getting dumped by the cooler. It was a good idea, but almost immediately one of the sensors failed (don't remember which one) and caused the gauge to read maximum temperature. I didn't feel like coughing up the bucks for another sensor, so I just deleted it from the plumbing. Someday, I'll get another sensor and connect it all back up again.

If I recall correctly, Darren does have two sensors monitoring the temperature drop across the transmission coolers in his van.

I'm anxious for your next set of updates.

I still want to see how the transmission does without the radiator in the circuit; I just don't think that the radiator should have to deal with the heat from the transmission.

Thanks Rob for the update and I'll also be looking forward to the results you find by taking the rad. of the picture. Thanks again Rob.

Just got done changing the ATF in my Astro. There was only 15,000 miles on the stuff since the rebuild, but I was curious to see what it looked like.
The ATF both looked and smelled good; the magnet in the pan had a very light layer of that silvery 'slime' on it. Maybe 15K miles is too early to tell, but I was pleased at what I saw. I'd like to think that the auxillary cooler really made the difference in the condition of the ATF.

Water Boy wrote:Unless you are an Ice Road Trucker
http://www.history.com/minisite.do?cont ... i_id=54692

Run the TruCool after the radiator.

I'm not sure on the 4L60E it there is a problem or not, but on my 4R70W equipped Crown Vic, the PCM wouldn't allow the convertor to lock unless the fluid was above 100 degrees F. This was to keep from damaging the TC clutch.

Although ambient air temp created a sliding scale, as a general rule in the summer (80F), it would get to over 100F in about 3 miles plumbed trans-rad-cooler, and never got over 180F. I had to switch it in the winter to trans-cooler-rad or it would go the whole 15 mile trip to work unlocked (20-30F). If plumbed like this in the summer, it would reach 220F with the A/C on.

I know that this was a different vehicle, but I can't help but wonder if the lock up clutch in a GM trans could be damaged by inadequate fluid opperating temps.

Having a fan on the cooler is a great idea, since the cooler is ineffective at low speeds unless sealed to the rad/shroud somhow.

For those of you above the Mason-Dixie line........

# Tru-Cool self-regulating coolers - it is the oil that regulates the cooler.
# Thicker oil that is below the ideal operating temperature bypasses the cooler through the upper two plates. When the temperature rises, it becomes thin enough to pass through the entire cooler.

Also, if you have the fan/cooler combo there is this switch.
Automatic electric fan controller activates at 180 and off at 170 degree

Info from http://www.transmissioncoolers.us/

I just spent an hour writing a very dedicated and technical post on this subject, and my Internet Explorer has just wiped it all out...... I`m pissed!

Maybe when I calm down, I may type it all out again...... ?

SoCalli V8 wrote:I just spent an hour writing a very dedicated and technical post on this subject, and my Internet Explorer has just wiped it all out...... I`m pissed!

Maybe when I calm down, I may type it all out again...... ?

Poor baby
Shoulda been using Firefox

http://www.mozilla.com/en-US/firefox/

Darren, I usually compose a long post in a word processor first (like Word) and then copy and paste it into my web browser. I learned to do this the hard way, of course, after having the same thing happen that you just experience.

I have manual control over the torque converter clutch lock up in my Astro and I played around with it during the long run to and from NECO. ATF temperature with TCC locked was typically 150F, with the TCC unlocked the temperature was 180F.
180F isn't bad as far as I'm concerned, but I like to see the ATF temperatures lower.

Yup, I second the word processor approach. My lesson came just recently while trying to write my steering column disertation. SoCalli you have my sympothies.

Thanks guys, yes I will do that in the future......

150-180*f is the good temp range to be in. If you can achieve this in your most harsh driving conditions ( worst example driving up grades, towing 4000lbs + ) you are doing good.

200*f should be considered as max temp.

Fit a trans cooler designed for a full sized motorhome, mine is 12inches X 12inches X 1inch thick, do not affix it to the a/c condensor because it will transfer heat and may cause your condensor to leak / crack/ loose freon.