Transmission cooler lines - leaking AGAIN [Archive]

KenR

11-23-2009, 17:14

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.

gophergunner

11-25-2009, 22:52

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.

DickWells

11-26-2009, 09:10

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.

conway

11-26-2009, 11:26

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.

WhiteTruck

11-26-2009, 21:14

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.

DickWells

11-28-2009, 08:30

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 ----------.:)

unclemikefusny

11-29-2009, 19:48

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?

Splitrimz

11-30-2009, 13:49

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>.

KenR

11-30-2009, 20:16

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!

mastertech

11-30-2009, 21:23

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 :eek:

Splitrimz

12-01-2009, 18:09

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>

painthorsemom

12-02-2009, 11:18

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!

conway

12-03-2009, 11:34

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.

gophergunner

12-07-2009, 09:17

DmaxMaverick

12-07-2009, 11:37

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.).

MikeyB

12-07-2009, 13:44

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

conway

12-09-2009, 06:34

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.

madmatt

12-09-2009, 08:51

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

gophergunner

12-09-2009, 12:29

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

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.

KenR

12-09-2009, 21:51

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.

KenR

12-09-2009, 21:53

madmatt

12-10-2009, 06:42

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.

IIRC, it had something to do with the convertor locking up while in neutral and the tranmission cold mode to help warm things up quicker on cold starts.
An Allison engineer and I were talking about this during a traning session last winter. But I can't recall the whole explaination he gave me. It was more then just poor quality lines though.

DmaxMaverick

12-10-2009, 10:58

IIRC, it had something to do with the convertor locking up while in neutral and the tranmission cold mode to help warm things up quicker on cold starts.

Hmmmm. This is interesting....And counterintuitive. During the cold mode (warm up mode), the TC remains open to expedite transmission fluid warming. The open converter allows for more fluid friction. Locking the converter would reduce this effect. Although there is very little TC resistance in neutral, it is still more than none.

An Allison engineer and I were talking about this during a traning session last winter. But I can't recall the whole explaination he gave me. It was more then just poor quality lines though.

Poor line quality. The line components are capable of handling significantly more pressure than the tranny will ever produce. The failure is at the crimps, lending to the likelihood of a question of quality. This isn't new. 6.5/2L oil cooler lines saw the same process. GM went cheap with the lines. Simple as that.

Although we shouldn't have to mess with this, the best solution is to just replace the crimp connection with a known quality repair. I recommend using Aeroquip type hose fittings, with a flare on the line. It is not expensive to do (you can do it yourself, or have any speed shop or AG supplier do it), and will never have this problem if done correctly. A second option is the same for 6.2/5L oil cooler lines. Remove the crimp collar and use hose clamps on the barb. Less permanent, IMO, but better than continually replacing the lines waiting for GM to get it right.

KenR

12-10-2009, 11:55

Just curious...does anyone know what the maximum pressure the transmission cooler lines will ever see?

Stlheadake

12-11-2009, 20:00

...A second option is the same for 6.2/5L oil cooler lines. Remove the crimp collar and use hose clamps on the barb. Less permanent, IMO, but better than continually replacing the lines waiting for GM to get it right.

I dunno about that. I did EXACTLY that on my wife's LeSabre. Lasted for about a year, then blew off. AFTER fixing on the side of the road, I 'permanently' fixed it by re-clamping and WIRING both sides so they can't pull apart.

Then I sold it...

jbplock

12-12-2009, 12:58

I dunno about that. I did EXACTLY that on my wife's LeSabre. Lasted for about a year, then blew off. AFTER fixing on the side of the road, I 'permanently' fixed it by re-clamping and WIRING both sides so they can't pull apart.

Then I sold it...

I've done the same fix (with two clamps side by side on each barb) on my daughters Saturn and Wife's Impala .. haven't had one come off yet but I still keep checking them frequently for any signs of seepage ... Several years ago I used the double clamp fix on a low side AC line for my 85 golf diesel.. a new line from the the dealer was over $100 .. I evacuated and recharged the system and it was still working when I sold the car a few years later..
:)

gophergunner

12-14-2009, 20:06

So here's my attempt at a fix...

First I used a tube cutter to cut the tubing as close to the hose crimps as possible to get the hose section out of the line.

http://i50.photobucket.com/albums/f350/gophergunner/IMG_0069.jpg

Then I went to town and got a piece of braided hydraulic hose made up with compression fittings. And just for the record, I was told these compression fittings are supposed to be able to handle 3000 psi or more, as they are regularly used with agricultural equipment. Thats what the guy at the parts store tells me anyways.

http://i50.photobucket.com/albums/f350/gophergunner/IMG_0073.jpg

http://i50.photobucket.com/albums/f350/gophergunner/IMG_0070.jpg

And here it is just loosely assembled, I won't tighten the fittings up until its all in place and fits properly into the truck.

http://i50.photobucket.com/albums/f350/gophergunner/IMG_0072.jpg

I hope these work, well I'm quite positive they will hold, I just hope they fit in properly. I just need to go to a hunting store and get a wire brush for cleaning shotguns and scrub out the new hydraulic hose to make sure I get the loose bits out of it. Shortly after I install them, I will be taking my truck to the dealer for transmission service.

I do have another line to do, just took pictures of the one though.

jbplock

12-15-2009, 16:31

Looks Great .. excellent idea! http://www.thedieselpageforums.com/tdpforum/images/icons/icon14.gif

Splitrimz

12-19-2009, 09:15

Excellent job, great photos. Please update and let us know how it is progressing.

Splitrimz

KenR

12-19-2009, 20:58

+1. I need to do a permanent fix for mine and like the way this looks.

Ambient temps here have warmed up a bit and my leaks are not nearly as bad. (Before you ask, yes, I did check the fluid level). Drove the truck to Vegas this week where it was in the 60's and had no leaks at all. I think the cold temperature theory has legs.

JohnC

12-20-2009, 09:30

Any reason you didn't go with flare fittings? Seems to me the aluminum tubing is the softest thing in the mix, which, I'd think, would make flares preferable to compression fittings.

DmaxMaverick

12-20-2009, 13:04

Any reason you didn't go with flare fittings? Seems to me the aluminum tubing is the softest thing in the mix, which, I'd think, would make flares preferable to compression fittings.

This is why I remain skeptical. The fittings are certainly rated and capable of 3,000 PSI. That is, if they are used with compatible line, which should be annealed steel tubing. Using compression fittings on aluminum lines (or soft steel) in a high-vibration application (like anything automotive) is not advisable. Swaged or flare fittings are always the preferred method in this case. It looks good, but I think it'll leak, and perhaps be worse than the current option from GM. I'd be concerned with a blow-out, compared to the minimal leak you are having now.

Quack_Addict

01-05-2010, 13:18

I think the cold temperature theory has legs.

I have heard GM issued a bulletin last year relative to leaky transmission lines on our trucks, specifically identifying 2006-2009 model year vehicles. Within that bulletin, they indicate the concern (line leaks) are more prevalent in the cold.

GM released new transmission lines in service that are supposed to be better than the old ones.

20759971 - Pipe Assy, Upper / outlet ($28.07)
20759972 - Pipe Assy, Lower / inlet ($25.60)
20759973 - Hose Assy, Trans Fluid Aux Inlet ($20.46)

My 2006 has developed a line leak with 45k miles on it. I went around the bush with the stealership yesterday about this and the service manager said the best they can do is get GM to pay for the parts if I pay the estimated $270 to R&R the effected lines. What a deal (sarchasm)... I suspect the dealer was going to eat the cost of the line/s just to get some billable labor on the clock.

Funny how a powertrain leak isn't covered by a powertrain warranty... but hey, they finally 'fixed' my intermediate steering shaft the 4'th time in for the same issue. If this is the way of 'the new GM', my `06 was my last new GM purchase.

mmcm267

01-05-2010, 14:54

Would you know if those part #s are good for an 07 Classic

Quack_Addict

01-05-2010, 16:33

Would you know if those part #s are good for an 07 Classic

As far as I know, the part numbers I listed should work for 06-09 model year trucks. The prices I have listed are stealership cost, so expect a hefty markup if calling your local parts department. Or you can get them for the indicated price at gmpartsdirect, if you pay shipping and don't mind waiting until they get around to shipping them out. I had one order from gmpartsdirect take about 3 months to show up last year; luckily I wasn't in a hurry for the parts and (for what it's worth) you're better off using a Ouija board to figure out when the stuff will show up because if you call them you pretty much get the "It will get there when it gets there" response.

IF any of you guys have the stealership do the work on your rig, make sure they use these part numbers and NOT the previous vintage lines. Sometimes changes go through where dealer inventory of old / obsolete stock can be exhausted before they start using the replacement part. If they use the old / obsolete part, you'll just find yourself going back to the well later to do it all over again...

Stlheadake

01-05-2010, 20:27

Funny how a powertrain leak isn't covered by a powertrain warranty... but hey, they finally 'fixed' my intermediate steering shaft the 4'th time in for the same issue. If this is the way of 'the new GM', my `06 was my last new GM purchase.

I was FURIOUS when I had mine in the shop for this two years ago. Less than 20K on the thing and the lines were leaking! The lines are 'consumable' and therefore not covered was the story I got.

Almost $600 bucks for the fix (THAT I SHOULD HAVE DONE MYSELF). If it wouldn't have been in the 20's outside, I'd have done it myself! Fortunately mine aren't leaking (YET!). My buddy has an 06, and his were leaking when he bought it last year. They were replaced then. They are leaking again. I'm going to give him those numbers so he can make sure that they are fixed 'correctly', or at least with the correct parts.

gophergunner

01-05-2010, 21:21

The lines are steel of some sort, magnet sticks to them anyways, so I'm not too scared of using the compression fittings.

I've used these compression fittings before on higher pressure lines, they work well for agricultural equipment so I know they will hold the pressure and vibration.

One other fix, as recommended by an aircraft mechanic, was to weld a JIC fitting onto the tubing and then simply have a couple short hoses made up with the appropriate fittings.

I have not put them on my truck yet, waiting until the next oil change. Then shortly after I am taking my truck in for tranny fluid/filter change.

daequitz

01-08-2010, 20:38

Stlheadake

01-08-2010, 22:02

Hell, when are they going to step up and fix them? 500 bucks and mine still leak!!!

Mark Rinker

01-09-2010, 09:14

My '06 is leaking - again...:mad:

EdHale

01-09-2010, 20:53

It must be the cold air. We don't have those leaks in Georgia, so far anyway.

Ed

mmcm267

01-10-2010, 04:54

With the weather we have been having for the last few days:eek: I check mine every day.;)

This morning it is 18*F and with the wind chill it is 8*. Yesterday at 7 AM with the wind chill it was 0*. I have my fingers crossed that mine will not start leaking.:(

EdHale

01-23-2010, 09:29

Well I lied in my earlier post. While under the right front of my truck a bit ago looking for a dropped wrench that didn't come out, I saw a red fluid leak. I guess I'm in the same boat as the rest of you now. @#$%%$#@

georgenmel

02-03-2010, 08:21

HELP!!!

Thanks for any help- Just found this sight and its really been helpful!- Just got my truck back from estimate at dealership - 35,000 miles & cooler lines leaking again- Had 1 changed while under warrty - Not so lucky now- They say it will be $760. to change all 3 lines -Anybody know what is involved in the fix - I'll fix myself using the updated hoses!! - Are the lines ends standard or do you need special GM tools - 1st time fix on my own, so any help would be REALLY appreciated --- Thanks,, George

cafritz

01-31-2011, 17:08

after today i think it is time for a class action lawsuit against gm.

i have had my truck for just over four years, love the truck. today my lines are leaking again, this is the fourth time. the first two times they were replaced under warrenty. last year the mechanic told us new and improved lines were used. i fought with gm and finally i had to pay for the parts and they covered the labor, we will see what tomorrow brings. i only have 117 kms on this truck and it has never been driven hard, but find it a little much that everytime it gets cold i am forking out a pile more money for something that has supposedly been fixed before. i think this is a problem with gm., they need to stand up to the line and fix what they sell. i paid 62 thousand for this truck and have had nothing but headaches with this line. when i talked to gm today the question i got was what do you want us to do.

JohnC

01-31-2011, 19:07

the question i got was what do you want us to do.

If you paid for the parts and the dealer installed them (regardless of who paid the labor) they should be guaranteed for one year or 12000 miles.

I suspect that if you cut the swedged sleeve off and put a $1 hose clamp on instead the leak would stop.

cafritz

01-31-2011, 21:42

If you paid for the parts and the dealer installed them (regardless of who paid the labor) they should be guaranteed for one year or 12000 miles.

I suspect that if you cut the swedged sleeve off and put a $1 hose clamp on instead the leak would stop.

amazingly i am three weeks over the one year warrenty period. i will repost tomorrow after i have had the truck to the shop and let everyone know what they say. thanks for the hint tho

SoTxPollock

03-02-2011, 20:29

How outragious to buy a truck costing more than double my first house cost and you're all having leaking transmission lines. Bet their supplier is China. I remember reading an article by Parker Hannifins talking about all the junk hoses flooding the market a few years back and no quality control whatsoever. They were cautioning people to be very careful where they purchased their made up hoses and lines from. Perhaps GM wasn't listening. Makes me glad I'm hanging on to my 02 dmax. Got 170,000 or so miles was in 8 degrees F cold a few months back for a couple of weeks. Never has a hose or line leaked. I think Parker is making some of the best hoses.

Stlheadake

03-03-2011, 00:26

Took the wife out looking for a new/used Tahoe past weekend. We looked at about 6-8 trucks. All from 05-08 EVERY ONE of them had leaking hoses! Some were leaking worse than others, but they all were leaking too.

To my untrained eye, these are different hoses than the Dmax, but they are leaking too. What gives? Though I haven't done it yet, I'm going to make the compression fittings for mine and try that. Not going to pay for inferior parts again!

mmcm267

03-03-2011, 06:15

Well mine finally started leaking:eek: It was never a thought that they wouldn't start leaking it was always when.:( I have decided to use a new kit out. I don't know if it is inappropriate on this forum to name the vender. I have the kit it looks great and I will be installing it this afternoon.;)

EdSpaek

03-03-2011, 07:11

If your repair kit is from all seasons by chance I installed the aluminun line repair kits over a month ago and have been in some -20 temps with no issues. So far they have worked great. You do have to remove the existing lines from the radiator and aux transmission cooler- suggest getting an extra line retaining clip or two from the dealer before you begin the install they are easy to lose

mmcm267

03-03-2011, 08:12

Ed, it is not Tony's kit. This is the Alligator kit and includes all new hoses and fittings.

Enigma

04-06-2011, 21:14

I have heard GM issued a bulletin last year relative to leaky transmission lines on our trucks, specifically identifying 2006-2009 model year vehicles. Within that bulletin, they indicate the concern (line leaks) are more prevalent in the cold.

GM released new transmission lines in service that are supposed to be better than the old ones.

20759971 - Pipe Assy, Upper / outlet ($28.07)
20759972 - Pipe Assy, Lower / inlet ($25.60)
20759973 - Hose Assy, Trans Fluid Aux Inlet ($20.46)

My 2006 has developed a line leak with 45k miles on it. I went around the bush with the stealership yesterday about this and the service manager said the best they can do is get GM to pay for the parts if I pay the estimated $270 to R&R the effected lines. What a deal (sarchasm)... I suspect the dealer was going to eat the cost of the line/s just to get some billable labor on the clock.

Funny how a powertrain leak isn't covered by a powertrain warranty... but hey, they finally 'fixed' my intermediate steering shaft the 4'th time in for the same issue. If this is the way of 'the new GM', my `06 was my last new GM purchase.

I have one hose leaking. I emailed gmpartsdirect cause I could not figure out the microfiche. They sent me these numbers for the 3 lines.

Thank you for your emailed inquiry to us at www.GmPartsDirect.com (http://www.gmpartsdirect.com/). We look forward to receiving your order. I have entered your supplied information into our licensed GM parts catalog and below are the part numbers requested.
20835127 Automatic transmission fluid auxiliary cooler inlet hose.
20835123 Automatic transmission fluid lower cooler inlet hose.
20759971 Automatic transmission fluid upper cooler outlet hose.

Quack, these differ from your part numbers. Are they giving me the old part numbers instead of the new and improved version?

BTW: It's only like $80 for all 3 lines at gmpartsdirect. The local Allison service center said they would install them 1 1/2 hr labor @ $90 / hr

mmcm267

04-07-2011, 03:37

Here is a DIY write up (http://www.duramaxforum.com/forum/how-tos-diy-write-ups/87933-how-alligator-tranny-coolant-hoses-kit-install.html) I did on another forum and you can see the Alligator kit.

It has been installed now for about 2500 miles and I have towed about 1200 mi with it. No leaks, works great.

JohnC

04-07-2011, 19:06

They sent me these numbers for the 3 lines.

20835127 Automatic transmission fluid auxiliary cooler inlet hose.
20835123 Automatic transmission fluid lower cooler inlet hose.
20759971 Automatic transmission fluid upper cooler outlet hose.

The 3 numbers I got late last fall were:
20835123
20835125
20835127

Your third number has been superseded.

I paid under $100 including shipping. If you can get them installed for $90, that's a bargain in my book.

gimpyhauler

04-16-2016, 14:16