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Thread: Transmission cooler lines - leaking AGAIN

  1. #1
    Join Date
    Dec 2001
    Location
    Park City, UT USA
    Posts
    27

    Default Transmission cooler lines - leaking AGAIN

    Did a search and couldn't come up with anything newer than a post from 2008.

    My 07 Duramax/Allison is on its second set of transmission cooler lines and they're leaking again at the crimp. The truck is out of warranty and the dealership won't warrant the lines they replaced. You'd think GM could make a tranny cooler line that'll go longer than 30k miles before leaking, and if not, at least back up the repair. Didn't know these were consumable parts.

    Anyone else have this problem? Anyone have success with custom made lines? I don't want to go through this in perpetuity.
    2007 GMC 2500HD LBZ, 4X4, CC, SB

  2. #2
    Join Date
    Apr 2007
    Location
    Alberta, Canada
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    311

    Default

    I've finally got a decent set for about a year now. My fourth set on my 2006 truck. They say they have 1 year warranty on the parts, but of course they will last long enough to be off that warranty and then they will leak again.

    I was looking for something made up, or aftermarket to replace mine last time...would still consider it just in case I need them in the future, but I haven't had any luck finding any.
    2011 VW Jetta TDI, pretty well loaded without leather.
    2006 GMC Sierra D-max, 4x4, 4 door, bumper, winch, Espar heater, and the HID lights are a nice touch too.....
    1986 GMC 3500, 454 on propane, 4 speed, 4x4, crew cab dually......the welding truck
    1984 Toyota 4x4 pickup, 4.3 V6, 700R4, Toyota t-case.......transforming into 4x4 cage buggy

  3. #3
    Join Date
    Jun 2000
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    Morrisville, VT, USA
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    I've seen enough complaints in here on those lines to make me wonder why mine aren't leaking in my 04 Sierra, with 112 K on the clock?
    I came accross a guy in a truck stop in PA, about 3 years ago, who had leaking lines in a borrowed truck from MA. He had added about 4 quarts of engine oil to the engine, and was swearing at the truck, because he didn't dare to move it! He had started the engine and couldn't find any engine leaks. I had all my tools, and offered to help him and he wouldn't accept any help, so I left. I didn't know about the leaking tranny lines at the time, but I'll bet he put oil in the wrong hole, and that he had trans. fluid all over the ground. I remembered later that the oil on the pavement did look red! Bet he had a fun day ahead of him. He should have accepted my help. With someone to watch while he ran the thing, it wouldn't have taken but a minute to find out where the leak was.
    2008 Jaco Seneca 35' motor home (Kodiak 5500 chassis). Pulling 18' Wells Cargo enclosed trailer, with 2016 Miata in it.

  4. #4
    Join Date
    Jan 2003
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    maui, hawaii
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    I understand that someone installed braided SSteel lines with a teflon inner coating (Titeflex brand SS hose) and silver soldered nuts on the transmission line tubing for the connection. He bought new lines to install the nuts on. Or another option, go to a hydraulic shop and have them make up a replacement with better fittings. Seems that this is a cold weather problem.
    1) '03 GMC 2500HD Dmax/Ali Ext/Short 4x4; 4" exhaust, egt and boost gauges; exhaust brake; Bilsteins; BD exhaust manifold; Oil Guard bypass; Lubrication pre oem fuel filter; Tekonsha Prodigy; Mag-Hytec differential cover; Suncoast V transmission w/deep oil sump
    2) '07 Classic GMC 2500HD Dmax/Ali Ext/Short 4x4'; Bilsteins, Silastic shackles, BD exhaust manifold; Oil Guard bypass; Lubrication pre oem fuel filter; Tekonsha Prodigy; Federico sway bars; Dipricol boost and egt gauges; Transgo Jr,, Mag-Hytec differential and transmission pan

  5. #5
    Join Date
    Feb 2001
    Location
    WI, USA
    Posts
    125

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    Dick,
    You don't have the problem, and likely never will, because it was rare to see them leak until the '06 model year. They must have changed suppliers, because it is very common now. Like it has already been said, shouldn't be that hard to make a decent line.
    The braided stainless line repair many have done to the 6.5 engine oil cooler lines was very successful. This would be a good fix, if local resources are available to do this.
    Carefully cutting off the existing crimp, and adding a decent constant tension clamp would work too. As conway pointed out, it does seem to mainly occur in cold weather, the hose must relax some then.
    2004 LLY SC LB
    ATS exhaust - BD LH Manifold
    Kennedy Diesel Mega Filter & Lift Pump

  6. #6
    Join Date
    Jun 2000
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    Morrisville, VT, USA
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    Default

    OK, I have Greg's A M lines on my old Sub. Wonder if he makes a set for the DM? Are you there, Greg?
    I don't intend to do anything with mine until they start leaking. If it ain't broke ----------.
    2008 Jaco Seneca 35' motor home (Kodiak 5500 chassis). Pulling 18' Wells Cargo enclosed trailer, with 2016 Miata in it.

  7. #7
    Join Date
    Nov 2009
    Location
    Upstate New York
    Posts
    1

    Angry 2008 Sierra 2500HD Transmission Cooler Lines Leaking

    While under the truck changing the oil this weekend, I noticed a slow leak around the crimps on one of the transmission cooler lines. Very nice, since I am just out of warranty with 38000 miles on it. My wife noticed spots on the driveway, but I couldn't see the drips with just a casual inspection. This, in my mind, is clearly a defective component problem. Have people been seeing this routinely?

  8. #8

    Default 2006 Lbz Transmission Cooler Lines

    Here is another one with the same problem. 1 Month out of warranty. Dealer replaced two lines, 0ver 500 dollars. I will be contacting Chevy, however I don't hold much hope for any satisfaction. I'll be watching for the first set of aftermarket replacements.

    This also started showing up in cold weather, leaking around the crimp on one line.

    Maybe the dealer is looking out for me, knowing that the other line is just waiting to happen. <grin>.
    1994 C3500 6.5TD CREWCAB DUALLY, Heath Turbomaster, cone style cold air intake, PMD cooler mounted under grill, Banks boost and exhaust temp gauges, OPS bypass, Air Lift rear bags.

    2006 LBZ LTD, 4WD, CREW CAB DUALLY.

  9. #9
    Join Date
    Dec 2001
    Location
    Park City, UT USA
    Posts
    27

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    The cold weather theory just might be the cause; mine just started leaking again now that the temps have gotten under 30F at night.

    Either way, completely inexcusable. The dealer said I'm 900 miles past the warranty period on the replacements...900 miles, like they weren't leaking a week and 900 miles before I took it in...and it'll be over $500 to replace them all over again.

    I love these trucks, but spending almost $40,000 dollars on one then dealing with this BS over and over is making me think about ditching it for my old '72 Chevy. Seriously, if you look at cost of ownership over the life of the vehicle they're not even on the same chapter much less page!
    2007 GMC 2500HD LBZ, 4X4, CC, SB

  10. #10
    Join Date
    Nov 2009
    Posts
    19

    Default leaking lines

    this is a common problem that gm is seeing with all the modle years as a gm tech i see at least 10 a month sometimes the same truck. the rubber hose that is connecting the metal parts at the crimps are where it is leaking the hose needs to be longer there it has a hard bend there that pulls on the hose no fix enless you know some one that can make a hose to fit

  11. #11

    Wink Leaking Transmission Lines Lbz 2006

    I picked up my truck from the dealer this evening..$625 for two transmission lines after they tacked on all the shop towels that got dirty etc. Needless to say I am Pzzed. This comes especially after really pursuing the warranty question I got the "Where did you buy the truck from" question.

    I have now read enough on the internet to realize that these transmission lines are a big "hidden" problem with Chevy. I am considering starting an on-line blog to see just how far reaching the problem is. A lot of diesel owners don't know about this or other diesel pages.

    I have read about various fixes but most run in the range of $500-600. I never tried to get a hose made at NAPA, I may just look into that when the weather gets more accommodating.

    Whomever comes up with a solution at half the cost is going to do well.

    There, I now fell better! <grin>
    1994 C3500 6.5TD CREWCAB DUALLY, Heath Turbomaster, cone style cold air intake, PMD cooler mounted under grill, Banks boost and exhaust temp gauges, OPS bypass, Air Lift rear bags.

    2006 LBZ LTD, 4WD, CREW CAB DUALLY.

  12. #12
    Join Date
    Nov 2009
    Location
    Eastern PA
    Posts
    15

    Default

    We just bought a used '06 that had leaking lines while it was on the lot. I had read about the problem before I bought it so I knew to look for it. The dealer just replaced them yesterday for us and the truck has less than 38, 000 miles on it. Now that it's getting much colder up here in NE PA, I hope I don't have the same problem again for a while. You would think that GM would do a permanent fix for this. It wouldn't be very hard to do!

  13. #13
    Join Date
    Jan 2003
    Location
    maui, hawaii
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    93

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    The temperature dropped to a cold 60 degree F. I got the dreaded leaking lines on my 07 but they are being covered by warranty. Waiting for the parts to come in.
    1) '03 GMC 2500HD Dmax/Ali Ext/Short 4x4; 4" exhaust, egt and boost gauges; exhaust brake; Bilsteins; BD exhaust manifold; Oil Guard bypass; Lubrication pre oem fuel filter; Tekonsha Prodigy; Mag-Hytec differential cover; Suncoast V transmission w/deep oil sump
    2) '07 Classic GMC 2500HD Dmax/Ali Ext/Short 4x4'; Bilsteins, Silastic shackles, BD exhaust manifold; Oil Guard bypass; Lubrication pre oem fuel filter; Tekonsha Prodigy; Federico sway bars; Dipricol boost and egt gauges; Transgo Jr,, Mag-Hytec differential and transmission pan

  14. #14
    Join Date
    Apr 2007
    Location
    Alberta, Canada
    Posts
    311

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    I'm not sure if the lines are steel or not....the colour always made me think they were aluminum but I have never actually checked for sure.

    But I've had leaky power steering lines for a while now. About $500 in hoses just to replace them all.....just the cost of hoses.

    Now I figure I will replace them once, take my old ones and cut the tubing where the rubber hose is crimped to it, then have a new hose made with compression fittings. It worked very well on my off-road Toyota, I don't see why it won't work on the Duramax.

    And if it works for the power steering lines, why shouldn't it work for the tranny cooler lines? They probably see much less pressure anyways. Only problem I can see is if the tubing is some goofy metric size that makes it difficult to find compression fittings for.
    2011 VW Jetta TDI, pretty well loaded without leather.
    2006 GMC Sierra D-max, 4x4, 4 door, bumper, winch, Espar heater, and the HID lights are a nice touch too.....
    1986 GMC 3500, 454 on propane, 4 speed, 4x4, crew cab dually......the welding truck
    1984 Toyota 4x4 pickup, 4.3 V6, 700R4, Toyota t-case.......transforming into 4x4 cage buggy

  15. #15
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    Apr 2001
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    CA
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    13,573

    Arrow

    Quote Originally Posted by gophergunner View Post
    I'm not sure if the lines are steel or not....the colour always made me think they were aluminum but I have never actually checked for sure.

    But I've had leaky power steering lines for a while now. About $500 in hoses just to replace them all.....just the cost of hoses.

    Now I figure I will replace them once, take my old ones and cut the tubing where the rubber hose is crimped to it, then have a new hose made with compression fittings. It worked very well on my off-road Toyota, I don't see why it won't work on the Duramax.

    And if it works for the power steering lines, why shouldn't it work for the tranny cooler lines? They probably see much less pressure anyways. Only problem I can see is if the tubing is some goofy metric size that makes it difficult to find compression fittings for.
    Do not use compression fittings on the PS/PB lines! The pressure can be too great (can peak over 2K PSI). Flare or swage only. You could use compression fittings on the return line, though. You can DIY with a flare kit and some Aeroquip AN fittings (any speed shop should have them, as well as Summit or Jegs). Measure the inside diameter of the hoses, and the outside diameter of the hard lines for the correct size. If they are metric, use the next inch size up for the tubing, but the hose should match, regardless if inch/metric (just make sure the couplers are the same size). Flares are very forgiving when it comes to matching sizes (which you can't do with compression fittings), and you can get "adapter" hose fittings with different hose to flare sizes (example: fit #6 hose to #5 tubing, which is common). AN number sizes represent 1/6ths of an inch (a #4 is 1/4", #6 is 3/8", etc.).
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  16. #16
    Join Date
    Dec 2004
    Location
    Colorado
    Posts
    73

    Default

    AN number sizes represent 1/6ths of an inch (a #4 is 1/4", #6 is 3/8", etc.).

    Just so there is no confusion. I think you mean each an number is 1/16th of an inch.
    Dang fractions!

    Mike
    Mike
    2001 2500HD
    "Are you gonna pull those pistols or whistle Dixie?"

  17. #17
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    Jan 2003
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    maui, hawaii
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    I am curious if the leaking cooler lines can be pinpointed to 6 speed trannys and ones that have had work done on them (e.g. TransGo Jr.). I understand that the phenomenon strikes newer trucks so maybe the six speed trannys have a slightly higher pressure that is causing the crimp to let go.
    1) '03 GMC 2500HD Dmax/Ali Ext/Short 4x4; 4" exhaust, egt and boost gauges; exhaust brake; Bilsteins; BD exhaust manifold; Oil Guard bypass; Lubrication pre oem fuel filter; Tekonsha Prodigy; Mag-Hytec differential cover; Suncoast V transmission w/deep oil sump
    2) '07 Classic GMC 2500HD Dmax/Ali Ext/Short 4x4'; Bilsteins, Silastic shackles, BD exhaust manifold; Oil Guard bypass; Lubrication pre oem fuel filter; Tekonsha Prodigy; Federico sway bars; Dipricol boost and egt gauges; Transgo Jr,, Mag-Hytec differential and transmission pan

  18. #18
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    Jan 2005
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    Southern Indiana
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    1,177

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    I've been told this issuse has something to do with cold weather idling.

  19. #19
    Join Date
    Apr 2007
    Location
    Alberta, Canada
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    311

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    Well its about that time again, time to replace transmission lines once more....

    Doing an oil change and I was just having a look to see whats going on under the truck, and sure enough the tranny lines are leaking. Must have just recently started as none of the fluid has hit the ground yet.

    So about 45000 km's on my 4th set of lines...has been just over a year so no more parts warranty for me.

    So if I can't (or shouldn't) use compression fittings on the power steering lines, can I use the compression fittings on the transmission lines? Or should I just flare the lines like was suggested for the power steering lines? I dug up my last set of tranny lines, so I will attempt to make a new set for myself using the tubing from the old set.

    This is seriously frustrating and annoying. I'm not even on my 4th set of tires yet.
    2011 VW Jetta TDI, pretty well loaded without leather.
    2006 GMC Sierra D-max, 4x4, 4 door, bumper, winch, Espar heater, and the HID lights are a nice touch too.....
    1986 GMC 3500, 454 on propane, 4 speed, 4x4, crew cab dually......the welding truck
    1984 Toyota 4x4 pickup, 4.3 V6, 700R4, Toyota t-case.......transforming into 4x4 cage buggy

  20. #20
    Join Date
    Dec 2001
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    Park City, UT USA
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    Quote Originally Posted by madmatt View Post
    I've been told this issuse has something to do with cold weather idling.
    I dunno - Mine started leaking again right when the weather started cooling off a bit, but I wasn't idling the truck any more than usual.
    2007 GMC 2500HD LBZ, 4X4, CC, SB

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