Cooler Quick Guide

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Transmission Cooler Installation Instructions


These PDF instructions supplied by
DERALE Performance Cooling.
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Transmission Cooler Installation Instructions


PDF instructions supplied by Hayden Auto

Transmission Cooler Quick Guide

The most often asked question is should I bypass the radiator cooler when I install a auxillary cooler.
Most cooler manufactures and automobile manufactures information we have read, recommends installing the coolers In-Series with the factory radiator cooler for maxium cooling efficiency.
So unless the manufactures who have spent 1000's of hours testing different installations are wrong, the suggested cooler installation is in-series......
Transmission > Radiator cooler > Auxillary cooler > then Back to the transmission.
If you must bypass the radiator because the cooler tube is leaking or for other reasons, be sure to increase the size cooler you install by 1 to 2 sizes.


This is a Quick application guide only.
Choosing the right cooler for your transmission will depend on Vehicle type and intended use.
If you are pulling mountain grades you may need to use a larger cooler. If you only tow twice a year for short distances than you may be able to install a smaller cooler.
Just remember that ADDING a auxillary transmission cooler you to the cooling system is adding to the available cooling capacity & protection to what you already have.

Small compact cars, No towing
  • Coolers with GVW ratings of 10,000 to 16,000 lbs.

    Mid-size cars, Light towing
  • Coolers with GVW ratings of 14,000 to 18,000 lbs.

    Mid-size trucks & full size cars
    Towing up to 5,000 lbs.
  • Coolers with GVW ratings of 18,000 to 24,000 lbs.

    Pickup Trucks, SUV's
    Towing up to 7,500 lbs.
  • Coolers with GVW ratings of 22,000 to 26,000 lbs.

    HD Trucks, Motor homes
    Towing up to 10,000 lbs.
  • Coolers with GVW ratings of 22,000 to 30,000 lbs.

    Super Duty trucks
    Large Motor homes
  • Coolers with GVW ratings of 28,000 lbs. and UP

    These applications and GVW ratings are assuming proper installation and that you are installing the cooler in-series.
    If you are not installing your cooler In-series, we suggest you increase the cooler size to at least the next level. Our automotive cooling kits are for 5/16" & 3/8" cooling line systems found on most cars and pick-up trucks.

    Heavy Duty Allison Transmissions require special high flow coolers. Allison coolers

    Most Dodge Trucks with the Cummings engine will require larger cooler inlets for the 1/2" and 5/8" lines they use. 1/2" NPT Industrial coolers

    Some late model FORD trucks (4R100 trans) use a cooler line by-pass at the transmission. If your cooling flow is restricted (low volume = less cooling) check or replace the by-pass.


    Before you order a cooler kit, be sure you have room to install the cooler you choose.
    Add 4" to the size of the cooler to accomodate the cooler hose. You never want to have a tight bend in the hose that might kink the hose.
    Normally the most effective place to install a cooler is in front of the radiator, in the fans air flow for maximum cooling. Mounting the cooler in front of the fan will insure that you are getting air flow (cooling) even in Stop & Go traffic. If you can not mount the cooler in the FAN's Air flow, then you might consider a Fan Mounted Cooler.

    And be sure to check if there is already an auxillary cooler installed from the factory.

    GVW ratings are used as a guide only and rating system only.
    Having a 24,000 GVW cooler added to your car or truck does NOT mean you can go out and load 3 tons of dirt to the back of you 3/4 ton truck.
    What it does mean is that when installed properly, the cooler will help protect your transmission fluid from an overheating problem while towing a 5,000lb. trailer.

    If you are in the Northern part of the country where you have extended periods of freezing cold weather, and you are installing a large cooler, we suggest the "Tru-Cool" self-regulating coolers. This will help warm your transmission up to operating temp. faster in the cold winter months.
    If you are in the South there is not as much need for this feature with warmer winters, unless you are adding a very large cooler or bypassing the transmission cooler in the radiator.

    *Some late model cooler applications may require additional fittings when installing a cooler kit.

    Part #     Name     Description Image Price