Article

99 Super Duty Transmission Cooler Installation

Note: Follow-on testing by the author comfirmed that there is no pressure drop on the return transmission oil line by adding the Hayden aux transmission cooler.

Let me note before I start that under the majority of driving conditions, the PSD 4R100 Auto transmission will perform perfectly without an additional transmission cooler. However, during my personal experiences of pulling an 8000+ lb. Fifth Wheel trailer through city stop and go traffic, pulling long steep grades at speeds below 25 mph and jockeying the trailer into a narrow parking spot, I have seen my PSD transmission temps rise and stay above the 200 degree mark (normally towing temps run between 150-185 degrees). Though the high temperature reading occurrences have been few and far between, they inspired me to seek a solution that would assist in ensuring I getting the maximum service life from the transmission. To that end, I initially installed a Summit High Performance Electric Fan (SUM-G4910) 900 cuft/min cooling fan (made by Perma-Cool) to assist in moving additional air over the stock transmission cooler. I could not find a way to mount the cooling fan directly in front of or behind the stock cooler, so I ended up mounting the fan in front of the air conditioner exchanger (the transmission cooler is second in a line of the four air exchange, radiant coolers. As it turned out, the air conditioner exchanger reduced the fans cooling airflow too dramatically to be effective for the transmission cooler. This brought me to pursing the installation of an additional transmission cooler. The cooler was installed in-line, after the stock transmission cooler, so that the transmission fluid gets additional cooling before it is returned to the transmission. . As you will note in the installation instructions, the additional cooler was installed in front of all other radiant coolers for maximum cooling efficiency. I had concerns that the additional cooler would keep the transmission temps too low, but, mostly because of the mounting location (cooler partial covered from direct airflow behind bumper), this concern turned out to be unfounded. I also integrated the electric fan I initially installed into the installation to cover those times when increased airflow is necessary to maximize cooling efficiency. The addition of the cooler did not measurably affect my non-towing temps (140 -145 degrees). My normal Fifth Wheel towing temps (see above) have been reduced by 15-30 degrees and have yet to exceed 145 degrees. Engaging the electrical fan at highway speeds had no measurable affect, however, on long steep grades at slow speed and when jockeying heavy loads into tight parking spaces, the fan assist has kept temperatures that use to range above 200 degrees to now read well below 160 degrees.
Installation instructions, including pictures, follow. As always, these instructions can be improved upon and recommendations for improvement are welcome and encouraged. Please read the entire installation procedure before proceeding.

Note: Perma Cool makes an integrated six pass cooler/fan (same 900cfm fan) that
would also work, but the best price I could find for the unit was over $50.00 more
than purchasing the Hayden transmission cooler and the Summit fan separately.

Note: Though it appears that moving the license holder will improve airflow to cooler, I confirmed
that moving the holder did not make a noticeable difference in cooling temperatures.

Note: Once the cooler installation is completed, you will have to disconnect
the cooler hoses to remove the bumper

Items Needed:

For Transmission cooler:
Hayden Model 679 Transmission Cooler
2' additional Hayden cooler hose (or suitable sub)
3/8" tube end 90-degree angle hose fitting
2ea, ½"wide x 1/8" thick x 12 3/8" long zinc plated metal straps
4 pop rivets 1/8"x ¼" long
4ea, ¼" x ½" long Bolt w/ nut and /lock washer
(4ea 1/8"x ½" bolt/washer/nut required if bolting vice pop riveting metal straps to bumper)

For Electric Fan:
SUMMIT G4910 HP Cooling Fan
3' Lightweight Angle (see fig 05)
8 1/8 x 1/8" pop rivets (or suitable small bolt/nut combo)
20 amp in-line fuse
Electrical wire (gauge as specified with fan)
20 amp switch

1. Without starting the engine, check and note the level of transmission fluid on the transmission fluid dipstick. At the completion of the installation, it will make bring the transmission fluid back up to proper level much easier.

2. Remove bumper. Before removing bumper, note its position in reference to the left and right side front fenders. To remove bumper, remove 3 plastic tabs that hold rubber cover to bottom of bumper. Remover two plastic tabs that hold bock heater cord in place. Removal of the plastic tabs is done easily with a small, wide (2 inch), flat pry bar. Remove 4 bolts (two each side) on front of bumper (Fig 1). Lay bumper face down on rug or other soft material to prevent scratching.

3. Cut two mounting straps from plated metal strap (ref Items Needed). Using the cooler as a template, align the straps over the cooler mounting holes. About ½" of the strap should stick out past the end of the cooler. Hold the straps in place with a pair of vise grips and place the cooler and mounting straps inside the bumper to ensure you have enough strap on each end to mount the cooler later. Center the cooler behind the license plate holder, ensuring the intake and outlet tubes point to the passenger side and are clear of the top and bottom of the bumper (Fig 2). Once you are happy with the alignment, remover the cooler and mark and drill the metal strap cooler mounting holes. Bolt the metal mounting straps to the cooler with bolt/nut and lock washers (Fig 3) (ref Items Needed). Replace the cooler in the bumper opening. Drill the bumper and mounting straps (use vice grips to hold strap in place while drilling) and attach the mounting straps to the bumper. I used pop rivets to attach the straps to the bumper, but small bolt/lock washer/nut combo will also work (Fig 2).

4. Cut cooler hoses. The hose that attaches to the cooler outlet closest to the top of the bumper should be 30" and the bottom outlet hose should be 20". Note: You may choose to leave the two hoses full length and cut at the appropriate time during Step 8. The hose that comes with the kit is 4' long, so after cutting 30" for the top outlet hose you will have an 18"section of hose to attach to the bottom outlet. You can try it, but the lower connection will be close and may result in the hose rubbing on the lower fins of the other coolers. Attach the transmission oil hoses to the cooler outlets using the hose clamps provided in the cooler kit. 30" tube goes on the top outlet. Hint: Coat outlet tubes with a little trans fluid and they will slip right on. At this point, if not installing the cooling assist fan, you can skip to Step 7; reinstalling the bumper.

5. Mounting Cooling Fan. The cooling fan is mounted behind the cooler so that the fan will pull cooling air through the cooler. It is necessary to make some mounts from lightweight angle to attach the fan behind the cooler to the bumper (Fig 4 & Fig 5). For reference, the pieces of angle that were used for the bottom of the mount were 6" long. Again, I pop riveted the mounts together and to the bumper, but they can be bolted. The fan is attached to the home made mounts using the bolts provided in the fan kit (Fig 6 & Fig 7).

6. Reinstall Bumper. Be sure to check its alignment in reference to the left and right front fenders. Reattach the block heater cord plastic tabs, but do not replace the lower rubber cover until after Step 9.

7. Route the new transmission cooler lines between the bottom of the radiator and the lower mount
(Fig 8). This will position them just below the cooling fan shroud for easy attachment to the existing transmission cooler return line. The lower metal line that attaches to the rear of the transmission is the return line. Following this line forward toward the front of the truck; close to the cooling fan shroud it will attach to a flexible rubber line (Fig 9). Loosen the rubber line clamp and push it a few inches back up the hose out of the way (will be used later). Place a pan under the connection to catch any transmission fluid that may drain from the lines when disconnected. Slide hose clamp over lower outlet hose (shorter hose) from new cooler (cut hose to length if not done earlier) and attach the 90 degree, 3/8" tube elbow. Hint: A little trans fluid will help it slip right on. Do not tighten the clamp yet. Disconnect the rubber hose from the lower metal transmission return line and attach it to the other end of the 90 degree elbow (Fig 10) (Recommend you do not cut the original hose in case you ever want/need to reconfigure back to original system). Place and tighten both hose clamps. Slide a hose clamp over the remaining (upper most, longest) hose from the new transmission cooler (cut hose to proper length if not done at Step 5) and then push the hose onto the metal return line and tighten the hose clamp (Fig11).

8. Remove the transmission fluid dipstick and start the truck. Let it run for a few minutes to circulate the transmission fluid through the new cooler. Wait for at least five minutes after shutting off the truck to check the level of the transmission fluid. Add fluid (type identified in owners manual) to bring the level up to the level you identified at Step 1. In my case, only 10oz of fluid was required to bring the fluid up to the proper level. Note: It only takes about 6 oz of fluid to go from the bottom of the fill indicator to the top of it…so be judicious when you add fluid…just a few ounces at a time once your "on the stick." Of course you will still want to do the transmission fluid level check as outlined in the owners manual.

9. There are several options for hooking up the electric cooling fan. I chose to hook directly into the battery on the driver's side. I chose a 20-amp push pull switch for my fan control switch and mounted it on the light control panel (Fig 12) (See my gauge mounting article for how to remove light control panel). The modifications (material needed to be cut away) to the back of the light control panel that were necessary to mounting the switch have led me to recommend you choose an alternate location. A better site might be to the right of the steering column where the ESOF switch would be located (Fig 13). In this alternate location, I think a rocker instead of a push-pull switch would work better. Hint: Use quick disconnects (bullet connectors) at the fan in case you have cause to remove the bumper at a later date.

That's it. Keep Cool! Keep Truck'n!