Bypassing Factory Transmission Cooler on a 2003 Chevy Trailblazer LT 4.2 I-6

Updated 10/13/2020 | Published 10/09/2020

Products Featured in This Question

Derale Series 8000 Plate-Fin Transmission Cooler Kit w/Barb Inlets - Class III - Efficient

(874)

$96.46

Derale Series 9000 Plate-Fin Transmission Cooler w/ NPT Inlets - Class V

(95)

$118.98

Question:

I have had the internal cooler in the radiator crap out 2 times now. Will the external oil cooler be able to cool the transmission sufficiently without going through the internal radiator cooler? I would like to completely bypass the radiator with the external cooler.

asked by: Jack B

Expert Reply:

It is possible to bypass the factory transmission cooler on your 2003 Chevrolet TrailBlazer, but I would not recommend doing this with the Derale Series 8000 Plate-Fin Transmission Cooler # D13503. The cooler is a Class III cooler and as such, it's not quite big or efficient enough to function as a primary cooler.

I contacted Derale and they recommend the Derale 9000 Series # D33604. This is a Class V transmission cooler which provides more effective cooling and measures 10-1/8" wide x 11-7/8" tall x 1-1/4".

expert reply by: John R