Transmission Coolers..

[{tpc}]

Ok, so here I am trying to search through the forums on this subject. And I keep getting lost in threads, I swear I could read these for hours, lol! Anyways, does anyone have a suggestion on an aux transmission cooler (to go along with the stock one from the factory tow package, I think) that would be fairly easy to bolt on? That won't cost an arm and a leg?

On top of that, would it be better to do this before/after/or during a fluid change? And would one be better served by a dealer fluid change (or the install of the cooler as well?)?

As a side note, I am also interested in some sort of extension that can be added to the side mirrors for towing, but I haven't looked for that yet.

Sorry for all the newb questions, but I want to make sure I do this stuff correctly. The wife drives this truck and if I do something that messes it up, its gonna be my ass lol.

 

[The_Roadie]

Plenty of discussions about tranny coolers. You might have to use a computer to search well instead of a phone, in case that's your access mechanism. Also check the archives many of us contributed to at trailvoy.

I use a Hayden. That should be a good search word.

Use a site-restricted Google search in case our search engine here is lame.

 

[marshall@pcm]

Our kits knock about 30 degrees off the temps.

 

[{tpc}]

Plenty of discussions about tranny coolers. You might have to use a computer to search well instead of a phone, in case that's your access mechanism. Also check the archives many of us contributed to at trailvoy.

I use a Hayden. That should be a good search word.

Use a site-restricted Google search in case our search engine here is lame.

Well I did a search that pulled up a lot of the word "hayden" but nothing specific. I am assuming that unless you specifically "replace" the factory cooler, that any cooler is an auxiliary cooler? That said, I found some hayden ones on ebay for a reasonable price (less than $50) but they have 3 different ones. I guess the difference is the size, and the larger than more it cools?

I also found some derale ones on e-trailer for around $50, again cost was dependent on size and "tube fin" or "plate fin", whatever that means to me I do not know.

The only difference I could tell between the hayden and derale ones were the haydens were shiny and derale were black. At least the e-trailer site allowed me to select my truck and gave suggestions based on that. Ebay isn't as friendly.

No offense marshall, your kit looked nice as well, and I appreciate the response but $220 is a bit out of the range I was looking at.

 

[RedEnvoyDenali]

You will get a lot of divergent opinions, so here goes mine.

I added my Tru-Cool when I pulled the pan, cleaned it out, added a drain for future work and changed ALL the fluid (13-14 quarts).

Here is how I changed my fluid. Some don't like this but it worked for me. Next time I will only do the 5 quarts in the tranny but I wanted to make sure I had a full load of Synthetic Fluid (Amsoil in my case).

Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

Here are some pics of my install. Very little trimming (top left corner) is required and a nice fit. By the way that is a 4589 Tru-Cool is by Long Mfg. I also put compression fittings on the tranny lines I cut (Drivers side), but if you don't like to cut steel lines PCM of NC has a nice fitting you can get that will allow you to spice in the cooler without cutting anything. By the way remember the sequence. Tranny to rad on passenger side, through internal rad cooler and out drivers side, then on to the cooler input, through cooler and out and back to tranny.

Here is why you want to install a cooler. As you see the 30 degrees that Marshall mentioned are very critical to tranny life.

Good luck with this install, it is not difficult but expect to spend an afternoon doing it. You will also need 14-15 quarts of good tranny fluid.

 

[xj2202009]

I had one installed when the transmission was rebuild. before you could feel the heat through the floor, the guy mounted just like the one in the the picture below, if you gonna tow upgrading the "servo" helps a lot and gives the truck a nice pickup.. not sure if I'm spelling it right.

You will get a lot of divergent opinions, so here goes mine.

I added my Tru-Cool when I pulled the pan, cleaned it out, added a drain for future work and changed ALL the fluid (13-14 quarts).

Here is how I changed my fluid. Some don't like this but it worked for me. Next time I will only do the 5 quarts in the tranny but I wanted to make sure I had a full load of Synthetic Fluid (Amsoil in my case).

Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

Here are some pics of my install. Very little trimming (top left corner) is required and a nice fit. By the way that is a 4589 Tru-Cool is by Long Mfg. I also put compression fittings on the tranny lines I cut (Drivers side), but if you don't like to cut steel lines PCM of NC has a nice fitting you can get that will allow you to spice in the cooler without cutting anything. By the way remember the sequence. Tranny to rad on passenger side, through internal rad cooler and out drivers side, then on to the cooler input, through cooler and out and back to tranny.

Here is why you want to install a cooler. As you see the 30 degrees that Marshall mentioned are very critical to tranny life.

Good luck with this install, it is not difficult but expect to spend an afternoon doing it. You will also need 14-15 quarts of good tranny fluid.

 

[glfredrick]

When I am on a restricted budget, I almost always end up shopping the salvage yard instead of the new parts counter.

There are a LOT of really nice plate-style coolers (more efficient than tube and fin types) that factory engineers spent a lot of time and money designing that one can have for $10 or so at most pull-a-part sort of places. Just look for something heavy duty like a 1 ton van, bigger truck, etc., then pull the auxillary cooler. I've done that countless times, especially for my off-road builds which have auxillary coolers on just about everything.

Otherwise, all the major brands have decent stuff, just get what fits and works.

Let me make one additional recommendation... If you are towing, it is adventageous to add an auxillary oil filter to the transmission.

I generally plumb that into the cooler line while I am doing a cooler install. The procedure is rather simple, just procure a universal oil filter remote mount (and they generally take the most common V8 common Ford filter, which is fine for this purpose) and plumb it in the correct direction of flow in either the hot or cold return line of the cooler lines. Make sure you change the filter at about 500 miles the FIRST time, then after that when you normally change engine oil. Why the early first change? I've found that in almost every vehicle I've done this, that the filter will be almost plugged in the first 500 or so miles the first time run. Yes, there is that much crud in the transmission oil! The stock sort-of filter/screen doesn't really remove gunk from the oil like a true filter, so a LOT of smaller particles get caught in the aux filter right away. As the oil gets cleaned it is not as much a problem. Typically, with this mod, shifts get smoother and firmer after a bit, as the valve body and small ports start to clear of built-up gunk.

 

[HARDTRAILZ]

I use a Hayden in addition to the stock cooler as well. Very simplpe to install and keeps the trans much cooler than before.

 

[tbyoda]

You can also access the tranny lines on the passenger side just near the windshield washer reservoir. IIRC the top line goes back to the tranny.

And you could use one of these nifty little gadget to connect to one the female gm fitting on the left so no cutting.

 

[{tpc}]

Thanks for all the info! I do have a couple more questions. I think I have figured out that choosing and installing the aux cooler won't be too much of an issue. It seems like just pick one you like and go, and I will probably choose a medium sized or large sized one, depending on cost. Now the questions.

1. Would one need to add more ATF to accommodate the additional cooler?
2. How does one explain this need to the dealer when getting the fluid changed?
3. Would you change the fluid before or after the cooler install?

The writeup on the fluid change is great, I just finished reading it, and frankly if it was "my" truck and not the "wifes" truck, I would probably tackle it myself. But only because I'm breaking my perfectly good stuff on my own lol. That and I would be driving it the majority of the time, so if anything would go south, I would have an understanding of what is happening and why. This isn't the case though, so likely I will have the dealer change the fluid, unless I can find paperwork somewhere that shows it was recently done. I think I mentioned in another thread that she had some work done on it in the past, and iirc, the last time I looked at the dipstick, the ATF looked nice and pink. I can't imagine the fluid looking ok if she had over 100k miles on it with no service done.

So hopefully someone can answer those questions above. Basically, aside from the need for a TB cleaning and thermostat replaced, the truck is running fine, and isn't throwing any other codes. The 4WD system is in good working order as I put it through its paces recently. I just don't want to mess anything up at this point.

 

[HARDTRAILZ]

1. Would one need to add more ATF to accommodate the additional cooler?
2. How does one explain this need to the dealer when getting the fluid changed?
3. Would you change the fluid before or after the cooler install?

So hopefully someone can answer those questions above. Basically, aside from the need for a TB cleaning and thermostat replaced, the truck is running fine, and isn't throwing any other codes. The 4WD system is in good working order as I put it through its paces recently. I just don't want to mess anything up at this point.

1. Of Course, the system now holds more volume.
2. Tell the dealer...I want to add an aux transmission cooler.
3. Does not really matter, but you will likely lose a bit of fluid on install, so before would be a bit better to do it.

---4WD...You have proof of TC fluid being serviced every 50K with AUTOTRAK II??? More important than trans service on these. The TC fails more often than Trans with lack of service.

 

[DocBrown]

I mentioned this in a previous thread to you, but I think it merits a repeat. Your 2003 had Dex III fluid. Depending on who changed fluid last, it might have Dex III or the new improved Dex VI. What ever you do, when you do the fluid change use Dex VI. It's synthetic, it's backward compatible, and it runs cooler than the Dex III. I have 160k on my trans. I had the valve body off last summer and it's in amazingly good condition. I did not use an axillary cooler with my 3500# travel trailer and I towed it through mountains with my TB.

 

[glfredrick]

I mentioned this in a previous thread to you, but I think it merits a repeat. Your 2003 had Dex III fluid. Depending on who changed fluid last, it might have Dex III or the new improved Dex VI. What ever you do, when you do the fluid change use Dex VI. It's synthetic, it's backward compatible, and it runs cooler than the Dex III. I have 160k on my trans. I had the valve body off last summer and it's in amazingly good condition. I did not use an axillary cooler with my 3500# travel trailer and I towed it through mountains with my TB.

It is, unfortunately, not the valve body that gets burned up from high transmission temps, or poor fluid management (though the ports and passages can get clogged). It is the clutch plates that one cannot see until full disasembly of the transmission that are effected. The valve body is basically just a slug of aluminum with channels to move oil from point A to point B on command by using a handful of poppet valves held against pressure by springs, and or as a holder for the couple of electrical solenoid valves that the PCM directs to change fluid direction or pressure. Looks complicated but it is just the valve... The real operation are the clutch plates and bands that transmit the power!

 

[DocBrown]

It is, unfortunately, not the valve body that gets burned up from high transmission temps, or poor fluid management (though the ports and passages can get clogged). It is the clutch plates that one cannot see until full disasembly of the transmission that are effected. The valve body is basically just a slug of aluminum with channels to move oil from point A to point B on command by using a handful of poppet valves held against pressure by springs, and or as a holder for the couple of electrical solenoid valves that the PCM directs to change fluid direction or pressure. Looks complicated but it is just the valve... The real operation are the clutch plates and bands that transmit the power!

I wasn't referring specifically to the valve body, as you said just a slug of aluminum, rather the separator plate and actuator pistons. If you have a cracked actuator piston or a check ball that blew through the separator plate it affects fluid flow, which affects performance, which causes excessive wear on the clutch plates. If all those parts are in good condition, the fluid isn't burned, and the transmission is operating perfectly, there is no real need to dig deeper and look at the clutches and bands to determine the overall health of the transmission. If its to the point that you are taking it apart to inspect at that level, you're already experiencing slippage or smelling badly burned fluid. A transmission can take short bursts of high temps without damage.

 

[CajunWon]

This is a new-to-me GMC Envoy '06.
Since I'll be towing in the Summer have been looking into adding an Aux.Tranny Cooler. BUT today I found it has an OEM AUX Tranny cooler. It is in the front, about 3ft long and 2.5" square mounted under the radiator. A rather simple fin/tube design. The fins are a bit rusty, enough that it surely impacts its' ability to perform. This could be a better cooler than a 7"x9" I had in my old Jeep.

What's a safe way to take rust off these fins? Thinking about using a steel brush followed by Naval Jelly & wash.

 

[djthumper]

This is a new-to-me GMC Envoy '06.
Since I'll be towing in the Summer have been looking into adding an Aux.Tranny Cooler. BUT today I found it has an OEM AUX Tranny cooler. It is in the front, about 3ft long and 2.5" square mounted under the radiator. A rather simple fin/tube design. The fins are a bit rusty, enough that it surely impacts its' ability to perform. This could be a better cooler than a 7"x9" I had in my old Jeep.

What's a safe way to take rust off these fins? Thinking about using a steel brush followed by Naval Jelly & wash.

To the best of my knowledge they all came with a transmission cooler. If it was added in I don't believe there was an OEM option for that.

 

[Mark20]

This is a new-to-me GMC Envoy '06.
Since I'll be towing in the Summer have been looking into adding an Aux.Tranny Cooler. BUT today I found it has an OEM AUX Tranny cooler. It is in the front, about 3ft long and 2.5" square mounted under the radiator. A rather simple fin/tube design. The fins are a bit rusty, enough that it surely impacts its' ability to perform. This could be a better cooler than a 7"x9" I had in my old Jeep.

What's a safe way to take rust off these fins? Thinking about using a steel brush followed by Naval Jelly & wash.

That is the power steering cooler. The OEM one is IN the bottom of the radiator. The one in the radiator is surprisingly large but the going recommendation is to add an external cooler.

 

[CajunWon]

That is the power steering cooler. The OEM one is IN the bottom of the radiator. The one in the radiator is surprisingly large but the going recommendation is to add an external cooler.

Drat! Thought I was in the clear.
I'll continue to look for a WriteUp on this addition. I've got the Radiator Adapter and Hayden 678 in my "Wish List" for when the weather warms. I think an inline filter is a good idea, but does it need to be a motor oil filter? Was thinking a fuel line filter would be less restrictive.

 

[IllogicTC]

Drat! Thought I was in the clear.
I'll continue to look for a WriteUp on this addition. I've got the Radiator Adapter and Hayden 678 in my "Wish List" for when the weather warms. I think an inline filter is a good idea, but does it need to be a motor oil filter? Was thinking a fuel line filter would be less restrictive.

Here you go. I'm sure there's more around here, and likely more at our sister site offroadtb.com.

http://gmtnation.com/f79/installing-external-transmission-cooler-6348/

 

[CajunWon]

Here is a video of the procedure:
Accessories and Parts by Derale for 2006 Envoy - D13035

Now that I see this should be no different than one I did for my Jeep, except for the radiator adapter.

 

[CajunWon]

Use 2nd Power Steering Cooler as an AT Cooler?
Mounted just below the OEM PS Cooler?

Mounting an AT Cooler is normally positioned forward of the radiator. This position introduces additional heated air to the radiator, but further cools the AT fluid as intended. Maybe our radiator is oversized enough where this is a non issue. But my last vehicle did heat up when towing the boat in near 100* weather, esp in our rolling hills. & I never tow the boat in cool weather.

Doorman sells a matching PS Cooler #918-300
Thinking PS fluid is under higher pressure than transmission fluid.

 

[glfredrick]

Use 2nd Power Steering Cooler as an AT Cooler?
Mounted just below the OEM PS Cooler?

Mounting an AT Cooler is normally positioned forward of the radiator. This position introduces additional heated air to the radiator, but further cools the AT fluid as intended. Maybe our radiator is oversized enough where this is a non issue. But my last vehicle did heat up when towing the boat in near 100* weather, esp in our rolling hills. & I never tow the boat in cool weather.

Doorman sells a matching PS Cooler #918-300
Thinking PS fluid is under higher pressure than transmission fluid.

Two thoughts...

First, it was not the transmission cooler mounting location that caused your vehicle to heat up while towing on a 100* day. It was TOWING on a 100* day! It would have heated up whether or not you had a transmission cooler in front of the radiator.

Second, you already have a transmission cooler mounted INSIDE your radiator that would have heated up your engine even MORE than not having an external cooler in place to cool the transmission oil as much as it does!

Oh, and the TB already has a PS cooler in place. It is mounted under the bottom of the radiator.

 

[CajunWon]

So, no harm in using a PS Cooler as an AT cooler.

btw: did you post of a spare K&N air filer? $25 shipped?

 

[Mark20]

You don't want to lose the PS cooler. Now that I realize cars have one, I see them under every hood I look. I guess that system generates a lot of heat and needs to get rid of it.

 

[{tpc}]

Ok back to question time for me again.

I am about to plunge into ordering this as the weather finally seems to be approaching a workable temperature for this weekend, despite the "snow showers" I am hearing about for tomorrow. I am likely going to go with a Derale unit that is 11W x 8-3/4T x 7/8D Inch in size, as opposed to the one that is 11W x 12T x 7/8D Inch in size. Basically, my thought process on this isn't in relation to cost (its a $17 difference) but rather my ability to mount it. Most of the threads I have read say bigger is better, but a lot of them seem to be using a 11 x 8.5 (or thereabouts) size cooler. So in general I am thinking I will have more difficulty with the 11 x 12 unit.

Oh so on the the question. Derale has the nice adapter for no cutting. My question is, should this be only installed on the stock aux cooler, or is it ok for it to be installed on the lines on the passenger side? The video I watched on etrailer showed it installed on an avalanche but the fitting was on the side of the radiator not the bottom. My worry is that if installed where the line enters the stock aux cooler, the bend in the line there is going to give trouble and possibly hit into something.

My other question is placement of the cooler. From what I have seen, it would make sense to place the cooler on the drivers side if one was using the fittings coming out of the bottom of the stock aux cooler (and/or cutting method with the lines). Would it be better or acceptable to place the cooler on the passenger side, if it was ok to the use the adapter on the lines on that side (the ones nearest the washer fluid bottle)?

Lastly, here is what I am thinking I should purchase:

Derale Transmission Coolers for the 2003 GMC Envoy

Derale Snap-In Radiator Adapter Fitting for GM

Derale High-Temperature Replacement Hose for Transmission Applications - 4' Long

Derale Universal Bendable Metal Mount Kit

Again I appreciate all the help and guidance thus far. To add to my questions above just a little, does anything I have listed here seem unnecessary? Like maybe the hose? Or is just a better to be safe than sorry? I am not with the vehicle at the moment nor do I have the kit yet to even try to confirm if any additional hose would be needed or not.

The universal kit seems like I could just buy it at lowes in necessary pieces, but for $5, was just easier to get. The thought of pushing rods though the radiator to attached the cooler did not put my mind at ease. Seems a bit better of a mount to use a bracket of some sort.

 

[CajunWon]

fwiw: I did pickup a 2nd power steering cooler. matches the oem ps cooler and plan to install as my tranny cooler just below the oem ps cooler. The mfg replied it meets spec for use as a tranny cooler. Weekends tied-up for several weeks, though hope to install in May.

 

[RedEnvoyDenali]

Ok back to question time for me again.

I am about to plunge into ordering this as the weather finally seems to be approaching a workable temperature for this weekend, despite the "snow showers" I am hearing about for tomorrow. I am likely going to go with a Derale unit that is 11W x 8-3/4T x 7/8D Inch in size, as opposed to the one that is 11W x 12T x 7/8D Inch in size. Basically, my thought process on this isn't in relation to cost (its a $17 difference) but rather my ability to mount it. Most of the threads I have read say bigger is better, but a lot of them seem to be using a 11 x 8.5 (or thereabouts) size cooler. So in general I am thinking I will have more difficulty with the 11 x 12 unit.

Oh so on the the question. Derale has the nice adapter for no cutting. My question is, should this be only installed on the stock aux cooler, or is it ok for it to be installed on the lines on the passenger side? The video I watched on etrailer showed it installed on an avalanche but the fitting was on the side of the radiator not the bottom. My worry is that if installed where the line enters the stock aux cooler, the bend in the line there is going to give trouble and possibly hit into something.

My other question is placement of the cooler. From what I have seen, it would make sense to place the cooler on the drivers side if one was using the fittings coming out of the bottom of the stock aux cooler (and/or cutting method with the lines). Would it be better or acceptable to place the cooler on the passenger side, if it was ok to the use the adapter on the lines on that side (the ones nearest the washer fluid bottle)?

Lastly, here is what I am thinking I should purchase:

Derale Transmission Coolers for the 2003 GMC Envoy

Derale Snap-In Radiator Adapter Fitting for GM

Derale High-Temperature Replacement Hose for Transmission Applications - 4' Long

Derale Universal Bendable Metal Mount Kit

Again I appreciate all the help and guidance thus far. To add to my questions above just a little, does anything I have listed here seem unnecessary? Like maybe the hose? Or is just a better to be safe than sorry? I am not with the vehicle at the moment nor do I have the kit yet to even try to confirm if any additional hose would be needed or not.

The universal kit seems like I could just buy it at lowes in necessary pieces, but for $5, was just easier to get. The thought of pushing rods though the radiator to attached the cooler did not put my mind at ease. Seems a bit better of a mount to use a bracket of some sort.

here are some pics of my Tru-Cool 4589 cooler (8x11x1 1/2) you can see the fit.

LPD4589

36

8 x 11 x 1 1/2

24.000K lbs capacity My tranny cooler hook up with pics - Page 3 - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum Hope this helps with your project.

Note the 24000lb capacity. Yes bigger is better but this should be enough for anything we can attach

 

[IllogicTC]

Note the 24000lb capacity. Yes bigger is better but this should be enough for anything we can attach

It's all about the BTUs man! This model is capable of dispersing of up to 21,000 BTUs. Not bad.

 

[{tpc}]

Thanks for the links. I actually went ahead and ordered the stuff the other day. According to derale's site the unit I got is "22000 GVW rated" so hopefully it should do the job. I am really more concerned about anything negative about placing it on the passenger side, and using the fittings that run along that side nearest the washer fluid bottle along with the "adapter", as I really don't want to have to cut any lines.

I suppose it really doesn't matter which side, nor which line, as long as the correct line in used. From as many times and threads I have read, I shouldn't have any issue figuring it out (I hope lol).

Its funny, but I almost feel more confident about doing this install than about doing the thermostat and throttle body cleaning that I will be tackling first. I suppose its more because I am afraid of some issue with having the battery removed while doing this, and the truck having to relearn everything. And the actuators for the venting system crapping out or whatever it is that happens...though I know the truck has had the battery replaced and nothing happened when that was done. Still I worry.

Maybe I need to go read more about the thermostat now hehe.

 

[glfredrick]

So, no harm in using a PS Cooler as an AT cooler.

btw: did you post of a spare K&N air filer? $25 shipped?

Yup... Let me know. It is a drop in model for the stock air box, but could be stand alone as well. Just not as sexy looking as a cone, but still a coffee-can style.

 

[RedEnvoyDenali]

It's all about the BTUs man! This model is capable of dispersing of up to 21,000 BTUs. Not bad.

Couldn't agree more. However not sure how many folks can relate to Btu's. Is 10,000 enough or not, and of course 20,000 is better but what is a good number. If we use gross weight everyone can relate to that since most people have an idea what their vehicle weights. Since transmissions generate their own heat i have always believed you should put the biggest (translated highest heat transfer) cooler in you can fit. I run my Tru-cool 4589 year round and it gets to -40 (C or F take your pick) for way too many times during the course of a winter.

 

[{tpc}]

Well I got this installed finally today. Not anywhere as near a pita as the thermostat and coolant sensor was but man those hoses are tight to get on, even with a little trans fluid to lubricate them.

Cut out a little more if the truck than I thought I would have to, but I didn't like the idea of the trans cooler resting on the radiator, so I made the opening a bit larger to make the install easier. Used the passenger side and the fittings nearest the washer fluid reservoir. This allowed for no cutting which was nice.

The hardest part was getting the one hose onto the existing trans line. It was so tight that I had to take out the washer fluid reservoir and set it on top the engine so I could get my hands in there and work it on. But at the end if the day it's done, no leaks, and I lost very little fluid at all. Still need to add maybe 1/4 quart I think, was near the bottom if the hash marks for "hot".

Thank you everyone for the help here, I appreciate it!