Gmt900 Aux Transmission Cooler

bajakid2 · March 19, 2009

Hey, I have searched but did not find anything exactly to what im looking for. Im about to install a transmission cooler onto my 2007 silverado 5.3. Im just curious what would be the easiest way to take off the transmission lines from under the truck near the cats? How do you get them out of the transmission? i haven't played with them yet only took a quick look with a flashlight that's really it.

Is there any little tricks that would make this install a breeze? Haha i know its a really tight squeeze under there.

Thanks again for the help

Travis

remington351 · March 21, 2009

You can do a search in the forum for some more help but I'll give you a rundown of what I did. First, make sure you buy a GM style quick-disconnect tool. The lines are push connect type, like the fuel line, but need a special tool to slide them from the keeper. Your question implies that you will be replacing the entire transmission line. The disconnects are at near the top of the transmission and are a pain to get at. Myself and several others here on the forum found it easier to just cut and splice a new line or some high pressure hose at the cooler connections rather than fight to get a new hardline routed from the trans to the cooler.

Good luck.

CapitalTruck · March 23, 2009

I installed a factory style (from GM accessories) tranny cooler on my GMT-800. It wasn't the easiest job in the world, but it wasn't the hardest either. If it comes with new lines, use the new lines (that's what I did). I was able to use a small screwdriver to undo the quick disconnect fittings. (put small flathead screwdriver under the little metal piece that slides in to lock the line in place). These pieces are supposed to be single use. I was able to buy new ones at the local dealer for super cheap (since they're the consistency of paper clips). Anway, I think you'll find that you'll be able to install the new lines. Just be patient and take your time. Also, if after you re-connect the lines you see any of the yellow paint on the end of the tranny line it isn't in properly. Additionally, the correct routing is from tranny to in-radiator cooler to external cooler to tranny again.

C & A s Dad · March 23, 2009

I do not want to take anything away from the OE cooler and it appears you already have it in hand. I know it sounds like "shade tree technology" when we talk about cutting the lines but this is really no big deal at all. All front wheel drive vehicles have some rubber line in the trans lines. You simply need to be sure you buy a good quality rubber trans line and if you are concerned, you can use 2 clamps per connection. You would identify the line coming from the internal cooler in the radiator, cut it with a tubing cutter, connnect a hose to the end coming from the radiator and route it to the cooler. Then route a line from the cooler back to the metal line going back to the trans. If you have the GM metal lines, you could even use the ends that connect to the trans cooler and let them run back towards the radiator lines and simply use a short piece of rubber line to connect the two.

Good luck.

BTW, you are doing the right thing by adding the aux cooler. IMO, every truck should have an aux trans cooler.

brims · April 24, 2009

I installed a factory style (from GM accessories) tranny cooler on my GMT-800. It wasn't the easiest job in the world, but it wasn't the hardest either. If it comes with new lines, use the new lines (that's what I did). I was able to use a small screwdriver to undo the quick disconnect fittings. (put small flathead screwdriver under the little metal piece that slides in to lock the line in place). These pieces are supposed to be single use. I was able to buy new ones at the local dealer for super cheap (since they're the consistency of paper clips). Anway, I think you'll find that you'll be able to install the new lines. Just be patient and take your time. Also, if after you re-connect the lines you see any of the yellow paint on the end of the tranny line it isn't in properly. Additionally, the correct routing is from tranny to in-radiator cooler to external cooler to tranny again.

That is how the factory system is done? I'm on the fence as to which way would be best. Aux cooler after the in radiator cooler could possibly cool the fluid to much, aux cooler before could let the fluid be up to 210 when going back into the transmission.

nfisherman · April 24, 2009

I added the GM parts tranny cooler to my '08 Yukon. My dealer wanted $200 to do the job. I did it myself to save some money and because I generally enjoy jobs like that. I even replaced the transmission lines all the way back to the transmission. The biggest lesson that I learned was that it would have been worth the $200 to me to have it done. It's a pain. It feels like you're taking half of the truck apart to get the cooler into position. I don't have a lift, so I was using ramps in my driveway. I was crawling around on concrete long after it was comfortable. I got the line connections off of the transmission, but I had to take of the transmission heat shield to get enough room. Even with that, it was a long process and it was quite a wrestling match to get the new lines connected. It got it done and it works great, but I don't think I'd ever do another one myself.

C & A s Dad · April 24, 2009

I installed a factory style (from GM accessories) tranny cooler on my GMT-800. It wasn't the easiest job in the world, but it wasn't the hardest either. If it comes with new lines, use the new lines (that's what I did). I was able to use a small screwdriver to undo the quick disconnect fittings. (put small flathead screwdriver under the little metal piece that slides in to lock the line in place). These pieces are supposed to be single use. I was able to buy new ones at the local dealer for super cheap (since they're the consistency of paper clips). Anway, I think you'll find that you'll be able to install the new lines. Just be patient and take your time. Also, if after you re-connect the lines you see any of the yellow paint on the end of the tranny line it isn't in properly. Additionally, the correct routing is from tranny to in-radiator cooler to external cooler to tranny again.

That is how the factory system is done? I'm on the fence as to which way would be best. Aux cooler after the in radiator cooler could possibly cool the fluid to much, aux cooler before could let the fluid be up to 210 when going back into the transmission.

Chris, I have never seen anyone (OE or aftermarket) route the fluid through the Aux cooler first. I would not recommend this. Go from the trans to the in radiator cooler to the aux cooler and back to the trans. If you are worried about overcooling in the winter months, add a thermostat or cover part of your cooler in the winter.

Just my .02.

Rat4go · April 24, 2009

I installed a factory style (from GM accessories) tranny cooler on my GMT-800. It wasn't the easiest job in the world, but it wasn't the hardest either. If it comes with new lines, use the new lines (that's what I did). I was able to use a small screwdriver to undo the quick disconnect fittings. (put small flathead screwdriver under the little metal piece that slides in to lock the line in place). These pieces are supposed to be single use. I was able to buy new ones at the local dealer for super cheap (since they're the consistency of paper clips). Anway, I think you'll find that you'll be able to install the new lines. Just be patient and take your time. Also, if after you re-connect the lines you see any of the yellow paint on the end of the tranny line it isn't in properly. Additionally, the correct routing is from tranny to in-radiator cooler to external cooler to tranny again.

That is how the factory system is done? I'm on the fence as to which way would be best. Aux cooler after the in radiator cooler could possibly cool the fluid to much, aux cooler before could let the fluid be up to 210 when going back into the transmission.

Chris, I have never seen anyone (OE or aftermarket) route the fluid through the Aux cooler first. I would not recommend this. Go from the trans to the in radiator cooler to the aux cooler and back to the trans. If you are worried about overcooling in the winter months, add a thermostat or cover part of your cooler in the winter.

Just my .02.

From what I've found, I agree with Trey on routing the aux cooler downstream of the radiator cooler. From what I remember of heat transfer, this will maximize the cooling effectiveness of both the radiator cooler and the aux cooler.

One more thing...another alternative to covering the cooler or finding a thermostatic bypass for cold winter operation (especially if you're using rubber hoses and clamps) is to just disconnect the rubber hoses at the aux cooler and connect them to each other using the proper barbed fitting during the winter. Quick, cheap, easy "Aux cooler bypass", and the radiator cooler probably has enough capacity in the winter unless you're running in the mountains with a big load.

I'd put caps on the aux cooler fittings to keep water and other winter junk from getting in the cooler during the winter if you do this.

CapitalTruck · April 26, 2009

Yeah, mine wasn't a real peach either. But after replacing all those lines I had to wonder if I would have even trusted the dealer to it anyway.

I added the GM parts tranny cooler to my '08 Yukon. My dealer wanted $200 to do the job. I did it myself to save some money and because I generally enjoy jobs like that. I even replaced the transmission lines all the way back to the transmission. The biggest lesson that I learned was that it would have been worth the $200 to me to have it done. It's a pain. It feels like you're taking half of the truck apart to get the cooler into position. I don't have a lift, so I was using ramps in my driveway. I was crawling around on concrete long after it was comfortable. I got the line connections off of the transmission, but I had to take of the transmission heat shield to get enough room. Even with that, it was a long process and it was quite a wrestling match to get the new lines connected. It got it done and it works great, but I don't think I'd ever do another one myself.

brims · April 26, 2009

That is how the factory system is done? I'm on the fence as to which way would be best. Aux cooler after the in radiator cooler could possibly cool the fluid to much, aux cooler before could let the fluid be up to 210 when going back into the transmission.

Chris, I have never seen anyone (OE or aftermarket) route the fluid through the Aux cooler first. I would not recommend this. Go from the trans to the in radiator cooler to the aux cooler and back to the trans. If you are worried about overcooling in the winter months, add a thermostat or cover part of your cooler in the winter.

Just my .02.

If no OE or aftermarket systems say to do it then there must be an advantage to it. When I install a larger cooler I do plan on using a thermostat. Before deciding to upgrade my aux cooler, I had thought about covering all or part of it.

kdogg · April 29, 2009

Hey, I have searched but did not find anything exactly to what im looking for. Im about to install a transmission cooler onto my 2007 silverado 5.3. Im just curious what would be the easiest way to take off the transmission lines from under the truck near the cats? How do you get them out of the transmission? i haven't played with them yet only took a quick look with a flashlight that's really it.
Is there any little tricks that would make this install a breeze? Haha i know its a really tight squeeze under there.

Thanks again for the help

Travis

What's the part number for the cooler you got?

C & A s Dad · April 29, 2009

"One more thing...another alternative to covering the cooler or finding a thermostatic bypass for cold winter operation (especially if you're using rubber hoses and clamps) is to just disconnect the rubber hoses at the aux cooler and connect them to each other using the proper barbed fitting during the winter. Quick, cheap, easy "Aux cooler bypass", and the radiator cooler probably has enough capacity in the winter unless you're running in the mountains with a big load.

I'd put caps on the aux cooler fittings to keep water and other winter junk from getting in the cooler during the winter if you do this. "

Rat4go,

This is a great idea for guys running in colder climates. You could even use an inline trans filter to connect the two lines instead of a barbed fitting. These inline filters are non restrictive and have a magnet in them as well to catch any metal.