Failed Transmission Cooler

[R Hood]

Has anyone else had a transmission cooler failure?

I took my 01 in for the new fuel filter change and they found that the transmission cooler (Allison) was leaking due to a split seam. They said that this has been a common failure but there had been no recall and it would not be warranty.

That will be $350.00, thank you very much!

Any info available?

[DmaxMaverick]

If it's common, they can really keep a secret.

These things happen, but hardly common. I get suspicious when a dealer makes statements like that. One dealer shouldn't have a rash of similar repairs when others don't. I don't think a tranny cooler would be a regional thing. Excessive corrosion in the salt belt, or heat issues in the S/W is one thing, tranny coolers shouldn't be in the same category.

[R Hood]

I agree with your logic, it seemed like a strange comment to me, also.

This truck has been a problem ever since my engine replacement last year (Dead Duramax-Warranty Fight). It makes me wonder if this failure is related to the sloppy workmanship that was done during the engine swap.

Even though this truck is an 01, it only has 58,000 mi on it. 13,000 on the factory re-man engine.

Another funny thing, when this dealer did a vehicle history, the engine replacement is not in the records!! What do you make of that?

[DmaxMaverick]

Interesting. Could be the dealer only listed the initial complaint, and that it was repaired. Who knows? There should be some reference to it. I would ask them. But, better yet, you may want to keep it a secret if you are planning to trade it in somewhere else later.

[FrankA]

I had a dealer do work on my 2001 max and one of the hoses they replaced burst after only a month. Coolant everywhere. Could not take the little problems that began to pop up so decided to give Gm another chance and bought a 2005 Dmax. Love it-- but it does seem to run hotter as others at this site have pointed out.

[JeepSJ]

I think I'd tell the dealer to stuff it and spend less than $100 on the biggest aftermarket unit I could find.

[DmaxMaverick]

Originally posted by JeepSJ:
I think I'd tell the dealer to stuff it and spend less than $100 on the biggest aftermarket unit I could find. There's nothing wrong with the OEM cooler. It's plenty big, and of the correct design. Most of the aftermarket "high performance" coolers are not so. They may be bigger, but in many cases, less efficient. A stacked plate design, like the OEM, is considerably more efficient than a larger coil type. $100 will likely get you a coil type cooler.

The problem is.... Location... Location... Location... Where have you heard that before?

[a bear]

Originally posted by DmaxMaverick:
</font><blockquote>quote:</font><hr />Originally posted by JeepSJ:
I think I'd tell the dealer to stuff it and spend less than $100 on the biggest aftermarket unit I could find. There's nothing wrong with the OEM cooler. It's plenty big, and of the correct design. Most of the aftermarket "high performance" coolers are not so. They may be bigger, but in many cases, less efficient. A stacked plate design, like the OEM, is considerably more efficient than a larger coil type. $100 will likely get you a coil type cooler.

The problem is.... Location... Location... Location... Where have you heard that before? </font>[/QUOTE]Big enough for most users. When working the truck hard in certain conditions (mostly stop and go driving) I've seen the limitations of the OEM cooler. Somewhere to the tune of 240 degrees. If you fall into the later catagory and decide on aftermarket I also agree that stacked plate is the way to go. Just be sure flow is sufficient as the Allison circulates a lot of volume.

[Ranch55]

I replaced the OEM cooler on my '02 and again on my '05 with an aftermarket stacked plate cooler made by the same manufacturer (Long's out of Canada) that supplies the OEM cooler to GM. It's more than twice the cooling capacity of the stock cooler. I mounted it in the same location using the stock connector fittings, no cutting or splicing lines. I did need to make my own mounting brackets, which was a very minor task using some 1/8" aluminum flat bar you can get at any hardware supply. It worked out great and dropped my tranmission temperatures about 30 degrees. I got it on-line at....... http://www.bulkpart.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=2&Category_Code=tru-cool-ind
Look at the price. Quality is very good. Been running it for 3 years now in an '02 model, and this year in an '05 Duramax.

[Ranch55]

I used the maxium cooling capacity model ... HB7

[jjackson]

Ranch55, I sent an email to the site you included in your post regarding the H7B cooler. Their response was that they do not recommend that cooler for the Allison, as they said the H7B has 1/2inch lines and our vehicles have 5/8th inch lines, so they are concerned about flow restriction. I haven't looked at mine recently, but I do seem to recall that they appeared larger than 1/2 inch. They said it would likely work, but in their words "it is your transmission, so do what you want", but they certainly sent me a CYA note of caution..????? Glad yours is working well for you. I pull a 13.5K 5th wheel, and haven't had much trouble, but have gotten close to 200 degree's on a couple mountain pulls.

John

[JeepSJ]

Originally posted by DmaxMaverick:
</font><blockquote>quote:</font><hr />Originally posted by JeepSJ:
I think I'd tell the dealer to stuff it and spend less than $100 on the biggest aftermarket unit I could find. There's nothing wrong with the OEM cooler. It's plenty big, and of the correct design. Most of the aftermarket "high performance" coolers are not so. They may be bigger, but in many cases, less efficient. A stacked plate design, like the OEM, is considerably more efficient than a larger coil type. $100 will likely get you a coil type cooler.
</font>[/QUOTE]The only thing wrong with it is the price! They are manufactured by Long and can be found much cheaper than what the dealer charges. You can find huge stacked plate versions for less than $100 - just do a google search for oil cooler or transmission cooler. I got one that is identical in size to the factory unit and I paid about $50 on-line.

Here is an example -
http://www.bulkpart.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=2&Product_Code=4739-1&Category_Code=tru-cool-hd&Product_Count=4

[Turbo Al]

I just installed my old winch on the truck yesterday and noticed the trans cooler was leaking a bit from one of the connections. Also noticed that it has come loose and will probably fall off unless it gets some attention :rolleyes: .

[Ranch55]

JJ DMAX......The reply you received from the supplier is only partially correct. The fittings on the '02 OEM stock cooler are 1/2" NPT fittings into the cooler, with 5/8" fluid lines. The aftermarket Long's cooler is exactly the same, 1/2"NPT fittings into the cooler. This is why the stock cooler fittings will fit without cutting or splicing the lines. This is a high flow cooler with no restrictions.

[Ranch55]

JeepSJ.....The cooler you show a link to will not work for the allison. It has a restricted flow with the 3/8" fittings on the cooler. You DO NOT want to go with a smaller cooler supply line fitting than the OEM. As I said, the H7B cooler has the same exact supply fitting size as the OEM, no difference, and it is a high flow cooler with no restrictions.

[jjackson]

Ranch55, thanks for the reply. To clarify, does your aftermarket Long's cooler also have 5/8th inch fluid lines after the 1/2 inch NPT fittings.? If so, I think I'll get the H7B, as it is priced at $65, which is a fair price, and based on your experience of significant heat reduction.

Thanks, John

[JeepSJ]

Ranch,

I threw that up as an example of a big cooler that could be had for under $100, without any particular trans or application in mind. Looks like you found the H7B on their site.

[Ranch55]

JJ-DMAX.......The cooler uses the stock 5/8" OEM lines on the truck and the OEM fittings from the OEM cooler, no cutting or splicing required. The inlet and outlet fittings on the Long's H7B aftermarket cooler is the same exact size (1/2" npt) as the stock '02 GM Long's cooler. These stock fittings connect to the 5/8" lines to the transmission. Later year model (at least 2005) OEM coolers went to metric thread fittings on the OEM cooler connections. So you might have to go to the dealer and pick up a couple of the 2002 year model fittings to thread into the H7B cooler. The fluid lines are identical, 5/8" O.D. on the lines up to the 2005 year model. The H7B cooler is a high flow cooler with no restrictions and will service the Allison very well.

[jjackson]

Ranch55, I am about to order the H7B cooler, but was wondering if you use your truck for towing, and if so, what kind of improvements have you noticed in temps since installing the new cooler..?

Thanks, John

[Ranch55]

JJ-DMax ..... Yes, I use my truck for towing, but not on a professional level as some do. My towing is usually limited to about 10,000 lbs. But some to half of that is in the hills and mountains of Central west Texas. Also on the open highway at highway speeds of up to 80mph. Slower towing in the hills and mountains pushes the transmission temp gauge up to 190 degrees. Normally it stays around 175 to 180. With this same cooler, my brother just recently completed a trip up in the Ozarks pulling his RV trailer seeing max temps of 190~195 on the trans. temp gauge. This was significately lower than when he pulled it with the stock OEM cooler getting temps around 220~230.\
Both of our trucks are 2005 CCabs, long bed, 4X4 with the Duramax. I also did the same with my 2002 Duramax CC, long bed, 4X4.
No towing trans temps stay around 165~175 maximum. This has also helped to keep engine temps down.
If I knew how to post photos on the forum, I have some good ones of the H7B installation.

[ 09-17-2005, 08:05 AM: Message edited by: Ranch55 ]

[jjackson]

Ranch55, thanks for the info. Did you have any trouble with the "re-attachment" of the stock lines to the new cooler from the standpoint that it would appear that the new cooler inlet/outlets may be closer together than the stock ones. Also, is that "sensor" that I see clipped to the transmission cooler mounting bracket on the lower drivers side in front of the radiator for the "mirror" temp readouts..? If so, I may relocated it.

Thanks again, John

[Ranch55]

JJ-DMAX..... You have mail with photos attached. See my earlier posts with some of the details for the fittings in case yours turn out to be the newer metric fittings instead of the 1/2"npt on the '02 model. Also notice how I slightly moved the cooler lines with some heater hose cushion added to prevent any rubbing on the lines.
Let me know if you received the photos okay.