blown trans cooler line

[HawkTown28]

I had noticed my transmission was not shifting quite right at certain times(it would kinda like slip as I got back on the gas after turning into a neighborhood), and I was about to go upnorth so I checked the trans fluid level. It was low, so I filled it up, it took a little less than 2 quarts, and then I did a little inspection, and found that the cooler line had corroded near the power steering pump and had sprung a leak. So I cut the corroded section out and replaced it with rubber trans cooler hose and 2 clamps on each end. Everything seemed good to go, so I drove upnorth, towing my boat(only about 2000 pounds), and it made it up no problem and survived the entire time upnorth offroading and what not no problem. then on my way home(about 150 miles into the trip), I started seeing like steam in my rearview mirror. So I got off the freeway and found a gas station. the entire passenger side of my TB and boat were coated in fluid. Come to find out the rubber hose I installed split right open, almost like it was sliced with a razor blade. the hole was about an inch long. I was able to cut the hose shorter and reinstall it, and the gas station luckily had the proper trans fluid, and it took about 2 quarts again to fill it back up. After I fixed it, it made it another 100 miles home no problems. So my question is why would the rubber trans line split like this if it's designed to be a trans line. It was not rubbing on anything where it split. Or is this not a recommended way to fix a leaking cooler line? And should I try buying an entire new factory metal line and replace the entire thing? I ended up buying trans cooler line from a different store and replaced the original rubber line I put in, but both hoses look like they're the same, so I'm afraid this new hose will just split again. Also where the cooler line enters both the transmission and the radiator seem to be very loose, but they are not leaking at all at those points, is this normal? I don't think I need to be afraid of transmission damage, I think I caught it quick enough, since it was only 2 quarts low, but I could be wrong?

[v7guy]

Moots blew his trans line 3 or 4 times, one of the times it split just like you're describing, he eventually went to some braided line.

[Trail X]

I have two rubber transmission lines spliced into my system for my cooler. I have them wrapped in braided stainless, just to prevent rubbing and as a strain relief of sorts. I went through 2 hoses before this because it turns out they were not rated for transmission use, despite being high pressure hydraulic lines.

I do know that rubber hoses are very susceptible to twist. Did the lay-line of the hose possibly get twisted upon installation? A 10 degree twist in a line can decrease it's service life by 90%. Was there a tight bend in the area? They also don't like tight bends. Was the failure near one of your tubing cut ends? Is it possible there was a small burr on that end?

[v7guy]

Interesting, I wasn't aware that twisting the hose can cause that kinda issue. Makes sense though now that you mention it.
I do know Moots issues are atypical, most people don't seem to have any issues with the rubber hoses.

[HawkTown28]

It is possible that the line was twisted a bit, but the new one I installed isn't twisted at all. And the line had a slight bend in it, but no where near enough to kink it or put to much stress on it. also the line split like right in the middle. But it was only split on the outer rubber layer which I found wierd. The inner rubber layer and fabric mesh seemed in tact. Also does anyone know if it is normal for the line connections at the transmission and radiator to be kinda loose. They don't leak at all but they do wiggle around freely.

[Trail X]

As long as your retaining pin/ring is in place at the transmission line connections, and they are not leaking, there's nothing to be worried about.

Your line failure seems odd. Any pictures of the failure?

[HawkTown28]

As long as your retaining pin/ring is in place at the transmission line connections, and they are not leaking, there's nothing to be worried about.

Your line failure seems odd. Any pictures of the failure?

Okay I'll keep an eye on the connections to be sure they don't start leaking. Unfortunately I don't have the split line anymore. But I guess to better describe it is that it was spilt lengthwise along the linE, on the bottom side of the line. The split was about 1 inch long. The only thing I can think is the line was not actually trans line because even though the guy at autozone said it was, it didn't say anywhere on the actual line that it was. The new lone I got at O'Reilly actually says "trans cooler line" on it. But they both looked very similar so I'm not sure. Kinda makes me weary to drive it upnorth again. So far it's been fine around town and the transmission is shifting normally, but idk if the extra load of a boat on the freeway for several hours will blow the line again. I now keep extra fluid and a spare length of line in my truck.

[Trail X]

The difference between the right hose and the wrong hose isn't noticeable with your 5 senses. It has to do with the rubber compounds used. I'd write it off as an anomaly or a bad line or an incorrect line. You've got the proper preparations just incase. I'd assume its fixed at this point. If it does fail again, I'd replace the hose again, but this time use compression fittings on the steel hydraulic line, and use the proper hose nipples for transition to the hose section.

[onebigburb]

Just because you didn't say any where. You state you cut out old metal line and used rubber trans. line? When you do something like that you should deburr the metal line and flare it so it doesn't slip/cut. If your truck has body lift that may have caused stress on line. Me personaly I would say the rubber is temp. fix it was aluminium for a reason. You can buy short section and fitting cut/flare as needed to fit new metal line in place.

[Opeth]

Why not just replace the hard lines with new ones from the tranny all the way up to radiator? Gives a good reason to need a body lift and you'd still be cheaper than having a shop install them

[Chango]

Anyone have part numbers for the line(s)that runs from the tranny to the fitting just short of the cooler... Righ inside the passenger wheel well?
Doing the diff swap tonight, noticed one of mine is leaking pretty good

Edit:
Ended up calling the dealer this morning.
15817500
15817501
15817514
15817515

[Trail X]

I'd check nalleygmc's parts website.

Maybe this link will work:
http://parts.nalleygmc.com/showAssembly ... evel=25306