Hello Hummer Fam.
2009 Hummer H3x 3.7L I5
137k miles
35" tires, OEM 18" Chrome Hummer Wheels

I recently changed my Transmission cooler Hoses, highlighted in yellow in the picture attached by following instructions listed in other posts for example.

The Rubber hoses which were leaking that I replaced.

The install went well enough, no issues, things looked peachy. I MADE SURE to use Oil Cooler Hose, like went out of my way to a shop that had the 3/8" Oil Cooler hose for peace of mind.


Completed Install. Nice and Pretty!

Little did I know, a few days later while I was on the Highway headed back home, going 70-75ish MPH on hwy59 in Houston, disaster struck. There is suddenly smoke all in my cabin, smell of burning oil, the motorcyclist beside me telling me that my piece of sheet is smoking and I hurriedly pulled over to the shoulder to asses the situation. There was a pool of oil under my car and I immediately knew what had happened. Here's a gif for the people who decided to read this far. Exciting.

Just another lovely day
https://imgur.com/7QZVXRu

After this fun experience, I turned off the car and enjoyed my tow ride home.

So, now, I reach out to you, the community for help and advice.
1. Did I use the wrong hose? If yes, what should I have used here?
2. Did I do something wrong, did something in the install look off?
3. Considering that I stopped maybe 30 seconds after things started smoking, I do not believe that I have grenaded my transmission, what do you guys think?
4. Most Transmissions operate at a max 150PSI (google searching), and these hoses are supposedly rated for 400PSI and 300F temp. What would have caused it to rupture like that?

Thank you all!

 

Your hose is marked "not for fuel injection" low burst pressure. Also, I do NOT recommend gear clamps on high pressure hose. Hose & Clamps to use:
Gates Oil Cooler Hose 400psi +300°F

 

I do not know who sold you the Hose "NOT For Fuel" to use with an auto cooler transmission line. That was in part good, because fuel line will also die from ATF attack..... but that doesn't mean it is hydraulic fluid compatible.

Transmission Fluid is not oil, it is basically hydraulic fluid. You need a hose that can handle trans fluid, they make trans cooler hose, buy that in the same size SAE J1019 or better. I would upgrade your worm clamps to #8 SS 1/2" wide bands while you are in there.

 

According to Marine Safety Standards (far exceeds the auto standards because your car can't sink if it busts a hose clamp), double worm gear clamps are required.... you did that, just get wider bands.

 

looks like it is fuel line not transmission hose. says so right on it in blue letters. probably not rated for high pressure fuel might be for low pressure like for carburetors

 

You got it. Fuel hose can be used when rated 30r9 =180psi. When you see "not for fuel injection" that sets you to burst pressure of 50psi. Transmission cooler lines pressure 30-50psi, yet spike to 85psi+. Don't be cheap here, consider the cost of the transmission replacement if you destroy it! Get the recommended hose and install with high pressure clamps! LIVE & LEARN.

 

So looks like the hose that was sold to me was NOT a high pressure hose, that is a mistake on my part for not double checking what I actually purchased. I will take your advice and recommendations and apply the fix asap, this time TRIPPLE CHECKING that the hose is the correct one.

I have my fingers crossed that this instance has not done any permanent damage to my transmission.

Thank you all for your input, it is very much appreciated!

 

Your still good driving off the highway. Btw, you partially flushed the transmission. Get some dexvi and don't forget to 86 those gear clamps. Instead double clamp with High pressure hose clamps.

 

Finally got around to replacing the hoses. This is how it looks, I couldn’t get it past the bubble flare far enough to get a clamp on. What do you guys think?

 

Flares are to prevent the clamp from sliding. Looks like you have it secured with high pressure clamps, yet you can back it up with those worm gear clamps you previously used. Open them up all the way so you don't have to disconnect the hose and install them on the furthest part of the hose to the line.
I recommend to clamp past a flare! Easy to add with a flaring tool.