The factory transmission cooling lines on Crew Cabs are in a very bad location. If you look under your truck, you will notice that the cooling lines are too close to the exhaust pipe and pre-cat. On my Crew the lines are only 1/4" away from the exhaust pipe. This is a terrible design or flaw on GM's part. What is the point in cooling the transmission fluid only to have it re-heated right as it re-enters the transmission. I have been using a velcro attached heat wrap made by DEI to deal with this problem. I have had this heat wrap on my Crew for at least 1 year and the exhaust is so hot near the cooling lines that I already have a hole burned through where it is closest to the exhaust pipe even though the wrap is rated to 1000*. If the exhaust is hot enough to do this much damage, imagine what the added heat will do to your transmission. Heat is the number 1 killer of transmissions and this factory flaw on the Crew Cab can easily reduce the life of the transmission.
Steve
Last edited by killian96ss on Wed Sep 20, 2006 10:47 am, edited 1 time in total.
Where else are you going to run the lines? Other side of the transmission has a prop-shaft spining nearby, thats not a good idea. Don't want them coming out of the bottom of the trans, to easy to break there. Don't want them on top either, as the might get pinched, and hot fluid is better than no fluid.
Also consider the speed at which the fluid moves through the tubing. I bet you see less than 10 degrees change in fluid temp across that section of the line. A flowing fluid will not collect near the heat that a static fluid will.
Now, with that said, don't get me wrong, I'm all for keeping the lines cool, and safe. However the tone of your post is that it's impending doom if you don't take care of these lines right away. When in reality there are tens of thousands of trucks running around with the stock lines, and they are fairing just fine.......
A highly suggested mod, perhaps, but I really don't see it as a factory flaw.
I still think it's either a flaw that was overlooked or GM was just extremely lazy since there is more than enough room for the tubes to have been bent properly giving adequate clearance. Please note that the heat wrap I am using is rated to 1000* and yet the exhaust pipe was still hot enough to burn through it over a few months of use. I can almost guarantee that the tube closest to the exhaust pipe is getting very hot which would translate into more than just a 10* temperature increase in the tranny fluid. The same tranny lines on my SS were in an even worse location being only 1/2" away from the right side cat. It wouldn't have taken GM much more effort to properly bend the lines on either vehicle so that they would have at least 3/4" or more clearance. GM is just lazy with some things.
Working in an Product Development office I can tell you they weren't lazy....Most likely swamped with a gazillion other things going on.
In the end, they don't melt, they don't kink, and they flow tranny fluid to the cooler.
Hard to tell from the pics, but are you sure that isn't an abrassion on the wrap, and not a melt. I have a hard time believing that 1000* wrap is melting in that location, and you don't ahve other problems like melted floorboards.
I agree there are better places to put them/bend them, however I do think they work just fine where they are.
2kwik4u wrote:Hard to tell from the pics, but are you sure that isn't an abrassion on the wrap, and not a melt. I have a hard time believing that 1000* wrap is melting in that location, and you don't ahve other problems like melted floorboards.
It is possible that the damaged area on the heat wrap was partly due to abrasion, however the wrap itself was very "crispy" in this area which indicates prolonged high temperature exposure. Have you ever looked at the tranny cooling line clearance on your CC? The lines on my CC are only 1/4" away from the exhaust pipe! The floorboards are not going to melt since they are much farther away. If they were only 1/4" from the exhaust pipes then I'm sure they would have problems also.
Haven't looked at mine in particular, but I have been under a couple Syclones with 4L80E transmission in them, which are a much tighter fit, and we've not seen a problem on those running the stock cooling lines to the trans on those. One of the trucks has a 4" downpipe that runs through there, and makes enough power to get the manifolds white hot on the D=dyno
I might crawl under there one of these days and get a look-see. perhaps they are worse than the pictures above, and previous body styles.
I still don't think it's really that detremintal to the tranny temps though. I'm going to refer back to the Syclone's that I've been around, and using stock lines on those tranny temps in the 175-180 range are not uncommon with a larger cooler in front of the radiator. I wouldn't thinking these would be any different, however I don't have any firsthand CC knowledge to back that up with.
The factory transmission cooling lines on Crew Cabs are in a very bad location. If you look under your truck, you will notice that the cooling lines are too close to the exhaust pipe and pre-cat. On my Crew the lines are only 1/4" away from the exhaust pipe. This is a terrible design or flaw on GM's part. What is the point in cooling the transmission fluid only to have it re-heated right as it re-enters the transmission. 
I have been using a velcro attached heat wrap made by DEI to deal with this problem. I have had this heat wrap on my Crew for at least 1 year and the exhaust is so hot near the cooling lines that I already have a hole burned through where it is closest to the exhaust pipe even though the wrap is rated to 1000*. 
If the exhaust is hot enough to do this much damage, imagine what the added heat will do to your transmission. Heat is the number 1 killer of transmissions and this factory flaw on the Crew Cab can easily reduce the life of the transmission. 
It only took me 10 months to post this picture! 
It wouldn't have taken GM much more effort to properly bend the lines on either vehicle so that they would have at least 3/4" or more clearance. 
