Reatta Owners Journal

How to install an axillary transmission cooler on the Buick Reatta.

Most transmissions can benefit from the installation of an axillary transmission cooler.  There are numerous charts that show that longevity of an automatic transmission goes up when the operating temperature of the fluid is lowered.  With most Reattas on the road today being higher mileage vehicles,  I believe an axillary transmission cooler is a good way to extend the life of these aging transmissions.

I recently installed a the Hayden Automotive 402 Ultra-Cool Tube and Fin Transmission Cooler Kit on my Reatta.  There are bigger coolers and smaller coolers on the market.  I selected the Hayden 402 cooler based on it being the largest size that I though would be a good fit for the Reatta.  It is easy to install without cutting the factory steel transmission lines by using the Hayden Automotive 393 Transmission Line Fitting Kit

Below are the steps needed to install the transmission cooler

Remove the negative battery cable from the battery before attempting to install the cooler.  DO NOT SKIP THIS STEP!  You will be working near the positive battery cable that has the metal bolt exposed.  Any metal parts, wrenches or the coat hanger wire that touch that positive battery cable bolt could result in personal injury or damage to the car.

1- Prepare to install the cooler

Things you will need.

1 - Hayden Automotive 402 Ultra-Cool Tube and Fin Transmission Cooler Kit
1 - Hayden Automotive 393 Transmission Line Fitting Kit
2 - Cushioned Loop Clamps
1 - 1/4" drill bit
1 - Plastic wire tie wrap (optional)

Tools and miscellaneous hardware needed:

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2- Remove the plastic cover to expose the radiator and front cooling fan,

You will need a 10mm wrench to remove the bolts at the top of the cover.  Then carefully pry up on the plastic fasteners in four places along the bottom.  Take care when prying up on the fasteners to prevent damaging the plastic cover or marring the painted surfaces.  Slide the pry bar tool up under the plastic cover but also keep it aligned under the head of the fastener to prevent damage to the cover.  The fasteners can be hard to get to come out but once enough pressure has been applied under the head they will let go all at once and pop loose.

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3- Install hoses

Now that you have the plastic radiator cover removed you are ready to mount the cooler.  The photo below is of my '88 model. I assume other models will look similar.  To make mounting the cooler as easy a possible I used holes that were already in place and not being used.  As you can also see there is a rather large hole to the lower left of the cooling fan where hoses can be ran into the engine compartment.

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The first thing you should do is clean off the back of the radiator fan and stick a rubber pad (included in the Hayden transmission cooler kit) in the location indicated by the arrow.  That will help prevent damage to the cooler fins when you are installing the cooler.  The fins are extremely easy to bend and hard to get straightened out again.

Next layout the transmission cooler on the workbench, or other flat surface, and install the hose on the cooler as shown and secure it tightly with the hose clamps included in the cooler kit.

The hose fits tightly over the cooler fittings.  Put a little lubricant around the opening of the hose to make installing the hose easier.  DO NOT over-tighten the hose clamps

DO NOT cut the hose at this point.  The hose must be cut after you have pulled it into the engine compartment.

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Have an assistant support the cooler at the front of the radiator while you fish the hose through the hole into the engine compartment using a coat hanger wire with a hook bent on the end of it to grab the hose as close to the center of the loop as possible.

In order for the hose to fit through the hole you will need to bend the middle of the loop in the hose sharply to get it started into the hole.  While your assistant holds the cooler in his right hand, have him keep the hose collapsed and feed it into the hole while you start pulling it with the coat hanger wire from the engine compartment to get the hose all the way through.  Take care not to damage any wires that might also go through that hole.

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4- Mount the cooler

Now that you have the hoses pulled into the engine compartment you are ready to mount the transmission cooler.  Start on the right side by placing a cushioned loop clamp around the top transmission cooler line as shown in the photo below.  Use a 1/4"-20 bolt 3/4" long to attach it to the hole in the metal bracket.  I recommend using one of the round plastic parts from the cooler kit as a spacer to keep the aluminum cooler tube away from the metal it bolts to.  You will need to enlarge the center hole it to 1/4" so the bolt will go through it.  DO NOT tighten the bolt all the way just yet.

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Mount the cooler on the left side using the same method using a 1/4-20 bolt 1-1/2" long bolt.  A 1 inch spacer is needed to get the cooler to clear the fan bracket that it bolts to.  I made a spacer out of thin wall 1/2" diameter steel tubing.

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Adjust the hoses so they are in proper alignment as they go through the hole in the radiator support and up to the top of the radiator.  You want the hoses to follow the shortest route possible.  There will be no excess hose left when you make the cut to connect it to the radiator fittings.

While holding the transmission cooler out away from the fan motor, tighten the mounting bolts to secure the cooler in place.  The bottom edge of the cooler should be slightly angle toward the front of the car when you get the clamps tightened properly.  You should be able to get your finger between the fan motor and  the cooler.  If not, loosen the clamps and adjust. When installed properly the cooler will be held by the hoses and clamps without being able to touch anything.

I added an old piece of rubber hose between the transmission cooler hoses and he hole in the metal radiator support to prevent any chafing of the hose where it goes through.  I don't know that it is need but it probably is a good idea to do that while you are at it.

This is how the cooler looks when mounted;

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5- Install the fittings

With the cooler securely mounted you are ready to connect the cooler to the radiator using the Hayden Automotive 393 Transmission Line Fitting Kit.  Start by disconnecting the top transmission line from the radiator using a 1/2", open end wrench, or a tubing wrench if you have one of those.  Be prepared for a small amount of transmission fluid to escape.

Screw the female fitting from the kit on to the end of the transmission line and tighten it up.  DO NOT over-tighten and damage the brass fittings!

Next screw the male fitting from the kit into the radiator and tighten snugly but don't over-tighten.

Maneuver the transmission line into a position (see photo below) so it will connect the best way possible to the hose coming from the cooler.  Then take your time to figure out the best place to cut the hose so it will reach both fittings.

Look at the hose and make sure it will reach both radiator fittings before cutting it.  Cutting the hoses to the correct length is the most critical part of installing the cooler!

After you are sure you will be able to connect both ends of the hose to the fittings cut the hose.

Connect the hoses to the fittings as shown in the photo below using the hose clamps provided in the cooler kit.  The hose fits very tightly over the fittings.  Lubricate the inside of the hose and use pliers if needed to get the hose to slide onto the fittings.  Don't over-tighten the hose clamps. 

When tightened properly you should see the rubber just starting to squeeze into the notches in the hose clamp.

I put a black plastic wire tie around the lines to prevent them from moving around and rubbing against each other.

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6- Check the hoses and fitting connections.

I let the car idle with the transmission in gear until the transmission lines warmed up.  Then I checked everything for leaks.  Seeing none, I drove the car for about 30 minutes stopping and checking periodically for leaks.

Once I got back home I checked for leaks again for the final time before installing the plastic cover over the radiator.

Contact me if you have questions or comments.



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