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Is Additional Transmission Cooler Needed On 2004 GMC Sierra When Towing A Long Distance


I have a 2004 GMC 1500 Sierra 4x4 regular cab truck with factory tow package. It has a transmission oil cooler in front of the radiator. I will be towing a 7000 pound enclosed trailer from Alaska thru Canada to BOise Idaho. WIll your Derale combination engine oil and transmission cooler work or do I need bigger coolers? Thanks,


Expert Reply:

If you have a transmission cooler already installed on your 2004 GMC Sierra 1500, it may be enough to handle the long journey you said you are planning on taking.

My first recommendation would be to install temperature gauges for your oil and also for the transmission fluid. Then hook your trailer up and drive it to find out exactly how it is doing. I recommend the Derale Temperature Gauge, part # D13009. I would recommend one for the oil temp and one for the transmission oil temp.

If you find that one or both have higher than normal temperatures, you can install either a cooler for one or the other, or a combination like the Derale Combination Cooler, part # D15902 . You can stack the newer cooler in front of the existing transmission cooler if room allows, but be aware that you may reduce the cooling capacity of the existing cooler if you install anything in front of it. If you have room and are able to install a cooler in another location under the hood, that may be an option.

If you do install coolers for either and drive in a colder climate, you will want to allow the engine to warm a bit since the fluid is going to be moving through the coolers. For any coolers you choose, please be aware of the fittings you require to complete the installation. I have linked you to our product page for transmission coolers for 2004 GMC Sierra trucks. As you can see they have different fittings to complete the installation based on the size of the engine. It looks like the transmission adapter fittings for your truck will either be part # D13018 or part # D13035.

expert reply by:
Jeffrey L

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