GM Transmission Cooler Lines Leaking, Home Fix Recommendations

DanMan_S · December 19, 2012

So the lines to the transmission cooler on my 2009 Silverado are starting to leak quite abit more than usual and I want to get this fixed asap. It's definitely not going to the dealership as they quoted me ~ 1000 CAD to make the repair...they want to replace the entire lines front to back, etc, etc. Seeing as the problem is only with the crimps at the small sections of hydraulic hose, I want to save myself the hassle and fix it properly. Especially since I've been hearing that the GM fix still has the same faulty crimps that will eventually leak again.

What did everyone use as their home fix for this problem? Any recommendations?

I've seen that a few people have used fittings such as the below.

http://www.etrailer.com/Accessories-and-Parts/Derale/D13032.html

8.1HD/ALLISON · December 20, 2012

I'm assuming its not under warranty anymore? You could cut the crimps off, flare the lines and attach needed connector like you have in link.

DanMan_S · December 20, 2012

I'm assuming its not under warranty anymore? You could cut the crimps off, flare the lines and attach needed connector like you have in link.

Definitely not under warranty. The connectors I linked don't even need to be flared as they are compression connectors. That's why I was mainly curious what others had done as I've seen arguments for using flared connectors and arguments using the compression connectors. The big concern is that the compression connectors shouldn't be used in high pressure applications but does anyone know what the transmission oil coolant line pressure even gets up to?

Badass69 · December 20, 2012

I wouldn't use that single ferrule brass junk. Use a fitting like this:

http://www.swagelok....s/fittings.aspx

Yes they are a lot more money but there is a reason for that. And don't even try and compare them to the stuff you linked at e-trailer. Too anyone that wants to run their mouth about these type of fittings...... they are clueless. Myself and all my coworkers trust our lives to them. I work in a steam generation plant and they survive for years at upwards of 350 degrees C with around 15000-16000 KPA behind them. This style of fitting is rated to whatever the wall thickness of tubing connecting them is. So if the tube is good to 30000 kpa, so is the fitting. I personally got to play with a burst chamber where we ruptured some standard .035" 3/8" tubing and it let go at 15300 PSI or roughly 105489 KPA........They will last on your truck forever. Now that engine cooler lines are leaking on my one truck again I am replacing the rubber section with braided stainless flex hose with 1/2" unions.

Edited December 20, 2012 by Notamember

DanMan_S · December 20, 2012

For an application such as this, a Swagelok is extreme overkill. I'm in the energy industry, specifically natural gas and oil transmission and we use Swagelok fittings quite often as well. But they are definitely not needed for an application like this. Keep in mind that the typical hose sections of the transmission oil lines are rated for a burst pressure of roughly 1000 psi and a working pressure of only 250 - 500 psi. If there was any concern about the pressure strength of the current components, we'd be having much, much bigger problems than the lines simply sweating when they start to leak. This is more of a longevity, convenience repair than trying to make sure that the components are absolutely bomb proof. We also need to keep in mind that this isn't a hydraulic system like the brakes that can see MASSIVE increases in the line pressure.

Edit:

Based on quick research, it seems that 30 - 50 psi should be the maximum pressure typically seen in the transmission oil cooler lines. The transmission coolers themselves are only tested to a max pressure of 150 - 200 psi. That makes sense since i've seen instances where guys have repaired the lines by simply cutting the hose, jamming the line into the hole, and tightening the piss out of one or two gear clamps...without flaring the ends of the tube.

Edited December 20, 2012 by DanMan_S

8.1HD/ALLISON · December 20, 2012

Yes i've seen that done too. You can go your way. If it were mine I would flare it at the minumun for peace of mind. Few dollars worth of fittings is much better than buying a new tranny cause your clamp came loose. JMO

Gurrzt · December 20, 2012

replace the stock hoses or lines with braided SS hose, they are good for over 300lbs pressure, and use either aluminum or dura-aluminum fittings.

DanMan_S · December 20, 2012

Yes i've seen that done too. You can go your way. If it were mine I would flare it at the minumun for peace of mind. Few dollars worth of fittings is much better than buying a new tranny cause your clamp came loose. JMO

I definitely intend to properly fix it, just thought it was funny that guys were able to get away with only hose/gear clamps. I just don't want to go to the other side of the spectrum and do an overly excessive fix on a system that won't ever see insane fluid conditions when in use.

Edited December 20, 2012 by DanMan_S

Badass69 · December 21, 2012

Overkill....completely. As are the guys that have hydraulic hoses made for their trucks as well. Do I ever want to look at them again in my life of the truck with me? No. So if I install something that is pretty well guaranteed to not fail because it's "bombproof" so to speak it's a pretty simple decision. I don't see the Swagelok stuff as a large investment by any stretch of the imagination, it's cheap in fact compared to the garbage GM will sell you.... We have pressure systems tubed in in 0.049" wall 1/2 tubing that sees pressure you measure in millimeters of water column..... that's overkill. I like the fact these handle massive temperature swings, vibration and corrosion resistance without a hitch.

Hose clamps do work just fine and I have done it a few times in the past. In fact the mickey mouse brass will likely work as well but you are the one seeming concerned about longevity with them.

It's not a difficult thing to fix, put it that way. You seem to have already figured out what you want so let us know how it works for you.

Edited December 21, 2012 by Notamember

ujtruck · December 21, 2012

hose clamps here, good to go - mine is a truck not an Air Craft

JrocK817 · December 21, 2012

For an application such as this, a Swagelok is extreme overkill. I'm in the energy industry, specifically natural gas and oil transmission and we use Swagelok fittings quite often as well. But they are definitely not needed for an application like this. Keep in mind that the typical hose sections of the transmission oil lines are rated for a burst pressure of roughly 1000 psi and a working pressure of only 250 - 500 psi. If there was any concern about the pressure strength of the current components, we'd be having much, much bigger problems than the lines simply sweating when they start to leak. This is more of a longevity, convenience repair than trying to make sure that the components are absolutely bomb proof. We also need to keep in mind that this isn't a hydraulic system like the brakes that can see MASSIVE increases in the line pressure.

Edit:

Based on quick research, it seems that 30 - 50 psi should be the maximum pressure typically seen in the transmission oil cooler lines. The transmission coolers themselves are only tested to a max pressure of 150 - 200 psi. That makes sense since i've seen instances where guys have repaired the lines by simply cutting the hose, jamming the line into the hole, and tightening the piss out of one or two gear clamps...without flaring the ends of the tube.

I just fixed a leak on my wife's trailblazer. I cut the stainless line out, replaced that section with a rubber tranny line, same diameter. Clamped it down with high pressure hose clamps. <~ the ones used for fuel lines. Its been at least 5,000 miles with no problems at all. Like you said, there is barely any pressure going through them lines.

Just make sure it does not rub on any exhaust parts (obviously) not sure where your lines run because i havent looked but on the TB it was a tight fit to get me hands in there.

sport20 · March 30, 2013

hi guys

do anyone have a list of exactly what size and what parts are needed to fix this issue. i need to do mine also

CapitalTruck · March 31, 2013

Mine crapped out on my GMT-800. They lasted about 120k miles. I just replaced them with factory OEM ones. If they go another 120 I'll be okay with that. There weren't that expensive. Though replacing the long section of line that runs to the transmission is a biatch.

yahoo hickaboo · May 26, 2020

On 12/19/2012 at 2:21 PM, DanMan_S said:

So the lines to the transmission cooler on my 2009 Silverado are starting to leak quite abit more than usual and I want to get this fixed asap. It's definitely not going to the dealership as they quoted me ~ 1000 CAD to make the repair...they want to replace the entire lines front to back, etc, etc. Seeing as the problem is only with the crimps at the small sections of hydraulic hose, I want to save myself the hassle and fix it properly. Especially since I've been hearing that the GM fix still has the same faulty crimps that will eventually leak again.

What did everyone use as their home fix for this problem? Any recommendations?

I've seen that a few people have used fittings such as the below.

http://www.etrailer.com/Accessories-and-Parts/Derale/D13032.html

Back in the 80's all we did as pro mech's was use GOOD hose clamps and DOUBLE them opposed, 50 years, and never a problem on CUT line, NO BARBS. Have a good day. 400 Hydramatic, Powerglide, 350 Hydramatic.