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Add OEM-Style Transmission Cooler to Your 4.6L Tundra for Under $400

Discussion in '3rd Gen Tundras (2014+)' started by JohnLakeman, Nov 7, 2020.

  1. Nov 7, 2020 at 5:41 PM
    #1
    JohnLakeman

    JohnLakeman [OP] Burning Internet Daylight

    Joined:
    Feb 21, 2019
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    Messages:
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    Male
    Outside of Weird, TX
    Vehicle:
    2017 MGM DC TSS 4.6L
    TRD Pro grille, 2018 LED Headlights, Undercover Flex bed cover, Neoprene seat covers, Bed/tailgate mats, Power tailgate lock, auto headlights, illuminated key switch
    Warning: This thread series (Parts 1-4) is written for 4.6L Tundra owners with little knowledge about retrofitting an auxiliary transmission fluid cooler to a truck that never had one. It is necessarily long and detailed to inform those owners.

    The 4.6L Tundra has a respectable Trailer Weight Rating (TWR 6400-6800 pounds), but 4.6L Tundras haven’t been equipped with the tow package since MY2013. This thread series (Parts 1-4) will show those owners how to retrofit an auxiliary transmission fluid cooler to 2014-2019 4.6L Tundras using purpose-specific Toyota parts from prior years, and an aftermarket Hayden 679 transmission cooler. This retrofit will allow 4.6L owners to fully utilize the towing potential of their 4.6L Tundras, while insuring transmission reliability. Approximate cost for this retrofit is under $400.

    The Hayden 679 trans-cooler was chosen because it is an OEM-style plate-and-fin heat exchanger that has reduced air-flow blockage to following heat exchangers compared to a stacked plate configuration. This exchanger has plenty of cooling capacity, is highly cost effective, and has inexpensive OEM-style 3/8” push-on hose barb connections. The cooling capacity of this trans-cooler is advertised as suitable for GVWR of 22,000 pounds, or towing up to 10,000 pounds.

    This thread (Part 1: Fitting Hayden 679 Trans-cooler) will apply equally to 5.7L Tundras that never had an auxiliary transmission cooler installed since the grille mounting area is identical. Subsequent threads (Parts 2-4), however, will apply uniquely to the 4.6L 1UR-FE engine and A760E/F transmission.

    The Toyota parts required for this retrofit (see diagram below) consist of a transmission thermostat (Item 2, PN 32971-34030), cooler inlet hose (Item 3, PN 32941-0C040), cooler outlet hose (Item 4, PN 32942-0C050), transmission cooler-pipe-assembly (Item 5, PN 32907-0C040), plus two flange head bolts (PN 90080-10400), and eight hose clamps (PN 90466-16004). Item 1 is the existing transmission fluid warmer which remains unchanged.
    2013 4.6L Transmission Fluid Cooling.jpg
    Part 1: Fitting Hayden 679 Trans-cooler

    Fitting of the Hayden 679 trans-cooler follows the same pattern as previous installations on this forum (@Ruggybuggy), but provides detail that should minimize fabrication trial-and-error. A dimensioned photo will provide simple mounting bracket designs that will space the trans-cooler core approximately ¾” in front of the AC condenser. This spacing is intentional to match the OEM separation between AC condenser and radiator, and to avoid lower hose interference with the AC accumulator.

    The trans-cooler will be located high on the passenger side of the grille area with inlet/outlet connections located on the side of the exchanger, top and bottom. This positioning minimizes the length of mechanically-vulnerable and heat-sensitive rubber hose connections. Positioning the hot fluid inlet at the bottom connection insures that no air will be trapped in the heat exchanger to reduce cooling capacity. The Hayden 679 trans-cooler has a healthy 11.7” X 11” core area, and perfectly fills the area from vertical support to hood latch support. Relocation of the passenger-side horn is not required.

    Three mounting brackets are used. A single, bent-to-fit, 1” wide X 1/8” thick steel flat bar extends vertically from an existing M8-1.25 threaded hole in the body lower cross-member to a new drilled hole in the upper cross-member (see photos below). The vertical bracket supports the passenger-side flange of the trans-cooler and reacts the hose barb connection forces.

    Two smaller “Z” clip brackets bent from 16 ga (0.060”) steel sheet are used to mount the opposite flange of trans-cooler to the center hood latch support. Tools used for bending the brackets were a heavy-duty 5” vise and a hammer. Heat from a propane torch was also applied for bending the 1” flat bar, but any benefit was negligible.


    Lower Cross Member Threaded Hole.jpg
    IMG_0558.jpg


    Mounting bracket dimensions are shown on the photo below. Dimensions labeled “TYP” apply to both the top and bottom “Z” clips. Location of the top ¼” diameter trans-cooler mounting hole is dimensioned on the vertical support to set the trans-cooler vertical position. The trans-cooler mounting flange can be used as a template to mark the second mounting hole. The finished, painted mounting brackets are shown in the second photo.


    Support Bracket Dimensions.jpg IMG_0652.jpg

    Three holes will need to be drilled in your truck for the mounting brackets. One 5/16” diameter hole is drilled in the body upper cross-member for an M8-1.25 X 16mm bolt with nylon insert lock nut. Two ¼” diameter holes are drilled in the hood latch support for M10-1.0 X 12mm bolts and nylon insert lock nuts.

    IMG_0567.jpg


    The top M8 fastener head in the vertical support will be near the edge of the grille. There is about ½” of clearance between the grille edge and the cross-member. Interference is unlikely, but the fastener head will be more or less visible depending on where that hole is drilled. If the hole is drilled too low, you may have fastener head interference with the cross-member shape.

    Placing a piece of ¼” plywood in front of the AC condenser to protect it from unexpected drill over-travel is strongly recommended. Locate and drill the 5/16” hole in the upper cross-member using the bottom bolt to hold the vertical support in position. Hole location in the upper cross-member will be critical to not miss the vertical support behind. Mark the vertical support through the drilled hole, then remove the vertical support to drill the matching hole.

    Similarly, leave the ¼” holes in the clips undrilled until the trans-cooler and clips have been fitted. Mark the hood latch support for the center of the installed clips, then drill the 1/4" holes in the hood latch support, centering on each clip. Mark the clips through the drilled holes and remove the clips to drill the matching ¼” holes.

    The final installation used Metric Class 12.9 socket head capscrews because they were available at Home Depot relatively cheap in the preferred black finish. The vertical support was installed first with M8-1.25 X 16mm capscrews and nylon insert lock nut (top only). The trans-cooler was then installed using (2) M6-1.00 X 12mm capscrews and nylon insert locks in two mounting holes of the passenger-side trans-cooler flange. The “Z” clip brackets were then installed to the opposite cooler flange and hood latch support with (4) M6-1.00 X 12mm capscrews and nylon insert lock nuts.

    IMG_0657.jpg
    IMG_0659.jpg
    IMG_0660.jpg

    Hose penetrations (7/8” diameter) were drilled in the angled plane of the radiator air deflector to minimize any binding or constraint of the hoses. Locations of the holes are obvious from the photo. Drilling the holes can be simplified by removing the air deflector from the truck (six easy plastic retainers). Rubber grommets (¾” ID) were installed in the drilled holes to prevent abrasion of the hoses.

    The fluid hose included in the Hayden 679 Trans-cooler kit will be exactly enough hose length to make final connections from the cooler-pipe-assembly to the trans-cooler. I observed that the Hayden hose is just slightly under ¾” outside diameter. If other aftermarket hose is used, it may be necessary to increase the hole size in the air deflector as appropriate. Four Toyota spring hose clamps, PN 90466-16004, will complete the trans-cooler hose connections.

    Part 1 Bill of Material: $87.81
    • (1) Hayden 679 Trans-cooler kit, $50.63*
    • (1) Steel flat bar, 48” X 1” X 1/8”thk, $7.98
    • (1) Steel sheet, 16 ga, 12” X 12”, $10.98
    • (2) Spray paint, primer and satin black, $8.54
    • (1) Grommet, 3/4" ID, Gardner-Bender GHG-1575, 3PK, $1.79*
    • (2) Socket head capscrew, M8-1.25 X 16mm (Everbilt 574324), $1.84
    • (1) Nylon insert lock nut, M8-1.25 (Everbilt 595089), $0.53
    • (6) Socket head capscrew, M6-1.00 X 12mm (Everbilt 574226), $3.72
    • (6) Nylon insert lock nut, M6-1.00 (Everbilt 594654), $1.80
    Total Cumulative Cost: $87.81


    Other Expenses
    Hole saw, 7/8”, $3.93*

    * Prices from Amazon, all other prices from Home-Depot


    Part 2: Install Cooler-Pipe-Assembly (Part Number 32907-0C040) is covered in this thread: https://www.tundras.com/threads/add-transmission-cooler-to-your-4-6l-tundra-for-400-part-2.77767/
     
    Last edited: Nov 12, 2020
  2. Nov 7, 2020 at 5:41 PM
    #2
    JohnLakeman

    JohnLakeman [OP] Burning Internet Daylight

    Joined:
    Feb 21, 2019
    Member:
    #26430
    Messages:
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    Male
    Outside of Weird, TX
    Vehicle:
    2017 MGM DC TSS 4.6L
    TRD Pro grille, 2018 LED Headlights, Undercover Flex bed cover, Neoprene seat covers, Bed/tailgate mats, Power tailgate lock, auto headlights, illuminated key switch
    Part 1: Fitting of Hayden 679 Trans-cooler was covered in this thread:
    https://www.tundras.com/threads/add-oem-style-transmission-cooler-to-your-4-6l-tundra-for-under-400-%E2%80%93-part-1.77739/#post-1971996

    Warning: This thread series (Parts 1-4) is written for 4.6L Tundra owners with little knowledge about retrofitting an auxiliary transmission fluid cooler to a truck that never had one. It is necessarily long and detailed to inform those owners.

    Disclaimer: This thread (Part 2) applies specifically to adding a transmission fluid cooler to 4.6L Tundras with A760 transmission. Toyota part numbers mentioned herein apply uniquely to 4.6L Tundras. The process is similar for the 5.7L Tundra, but IMPORTANT PART NUMBERS ARE DIFFERENT.

    Part 2: Install Cooler-Pipe-Assembly (Part Number 32907-0C040)

    The transmission cooler-pipe-assembly, PN 32907-0C040, is the Toyota part used in prior-year 4.6L Tundras to convey hot transmission fluid past the engine to an auxiliary cooler located in the grille area, and then return the cooled fluid back to transmission. This cooler-pipe-assembly consists of two steel tubes (hot fluid supply tube and a cooled fluid return tube) that are welded together at mounting brackets on each end to form an assembly. The cooler-pipe-assembly is bent to conform to the side of the engine. This allows the Gen2 4.6L cooler-pipe-assembly to be installed on any Gen3 4.6L truck for retrofit of a transmission fluid cooler.

    Snip 3.jpg
    Installation of the cooler-pipe-assembly is not difficult, but detailed instructions for the process are impossible to write. The important point is to first identify which end of the assembly goes to the front, and which goes to the rear. The rear end of the cooler-pipe-assembly will have an “L” shaped bracket joining the two tubes; the front end will have a straight bracket across both tubes.

    Taping the ends of the tubes closed, or installing plastic caps on the tube ends before starting, would be smart to prevent dirt and debris from entering the tubes during installation. In fact, this would be good practice for any open tube ends or fluid openings before anything is done.

    The cooler-pipe-assembly installation will be made easier by having the truck on jack stands at the four corners. Fully extended jack stands will provide an additional 5-6” in chassis height. This doesn’t sound like much, but it will make a huge difference. Begin by feeding the assembly over the top of the frame cross-member, and into the void nearest the passenger-side of the engine. Stay below the front upper suspension components.

    Keep feeding the tube assembly forward until an obstruction is encountered. Rotate the assembly, and/or withdraw slightly and change direction, until the obstruction is cleared. Advance the assembly, and continue this method with each obstruction until the cooler-pipe-assembly emerges at the front of the engine just above the power steering hoses and below the alternator harness.

    IMG_0574.jpg

    Once in place, the cooler-pipe-assembly should rotate to fit close to the side of the engine when the rear mounting bracket is properly positioned. The cooler-pipe-assembly is secured to the engine at two points using flange head bolts, PN 90080-10400. At the rear, the L-shaped assembly bracket will be bolted to a drilled and tapped boss in the cylinder case just above the flange of the lower engine oil pan (steel).

    Rear Mounting Bolt.jpg

    At the front of the engine, the cooler-pipe-assembly is bolted to a harness bracket attached to the bottom of the alternator. You will observe that the front cooler-pipe-assembly mounting bracket will align perfectly to a threaded weld-nut on the alternator harness bracket.

    Front Mounting Bolt (2).jpg

    I found it impossible to tighten the front bolt from under the truck. You can gain better access to this front bolt by turning the right front wheel to increase access into the wheel well. Pry out the plastic retainers on the front splash shield, and roll the splash shield up out of your way. The bolt head is still in relatively close quarters, but access is much improved though the wheel well.


    IMG_0572.jpg

    Specified torque on these two bolts is 10 ft-lbf (120 in-lbf). As with all fasteners on this project, you can forget using a torque wrench. You’ll find there just isn’t room. You’ll have to resort to the old-fashioned "tongue-in-cheek" method…oh, about this much (30 pounds?) on the end of a 4” wrench.

    A comment about which of the tubes is the hot fluid supply pipe, and which tube is the cooled fluid return pipe, is appropriate: At the transmission end of the cooler-pipe-assembly, the inboard tube-end (nearest the centerline of the truck) is the hot fluid supply pipe (transmission to cooler), and the outboard tube-end of the assembly is the cool fluid return line (cooler to transmission). Formed Toyota hoses connect the cooler-pipe-assembly to the transmission thermostat (covered in Part 3).

    At the front end of the cooler-pipe-assembly, the outboard tube-end is the hot fluid supply to the cooler, and the inboard tube-end is the cooled fluid return to the transmission (see photo above). Yes, if you’ve figured it out, the two lines do cross back near the rear mounting bracket in the trip up to the transmission cooler and back.

    To make the hose connections to the trans-cooler, connect fluid hose from the Hayden kit to the outboard tube end of the cooler-pipe-assembly. This will be the hot fluid supply hose once all connections have been properly made. Seat the hose fully against the hose stop, release and install the hose clamp insuring that the clamp is positioned between the hose stop and the hose barb. Route the hot fluid supply hose up to and through the lower penetration on the air deflector. Allow just enough length for smooth routing and uniform bends. The other end of this hose will connect to the bottom connection of the trans-cooler.

    Similarly, connect the cool fluid return hose to the inboard tube-end of the cooler-tube-assembly, and then route up through the upper penetration to the top trans-cooler connection. A single duplex hose stay about half-way up the hoses may be worth considering to prevent movement and abrasion.

    New Toyota hose clamps, PN 90466-16004, must first have the spring tension released by pinching the small clamp tab toward the opposite clamp edge. Once the spring tension has been released, the clamp will grip the hose, and its position can then be adjusted by compressing the tabs and moving the clamp along the hose to properly position. Hose clamps should always be positioned between the hose stop and the hose barb to prevent the hose from being pulled off the connection.


    IMG_0671.jpg

    If you have elected to test the system to confirm identity of the supply and return pipes, you can simply leave the hoses disconnected at the trans-cooler. Once the rest of the retrofit is complete, you can start the engine and see which pipe/hose flows transmission fluid. You will need to pre-fill the transmission with additional fluid (covered in Part 4). Have a helper sitting in the driver seat to start and stop the engine. Place a five gallon bucket under both hose ends. After a few seconds (7-10?) of engine run-time, flow out of one of the pipes/hoses will be muy rapido, meaning the engine will need to be quickly shut off.


    Part 1 Bill of Material: $87.81
    Part 2 Bill of Material: $87.49
    • (1) Cooler-pipe-assembly, PN 32907-0C040, $74.15*
    • (2) Flange bolt, PN 90080-10400, 2 @ $1.89 ea, $3.78*
    • (4) Hose clip, PN 90466-16004, 4 @ $2.39 ea, $9.56*
    Total Cumulative Cost: $175.30

    * Prices from Toyota of Cool Springs, September, 2020

    Part 3: Install Transmission Thermostat (Part Number 32971-34030) is covered in this thread: https://www.tundras.com/threads/add-transmission-cooler-to-your-4-6l-tundra-for-400-–-part-3.77848/
     
    Last edited: Nov 10, 2020
    Saltyhero13 likes this.
  3. Nov 7, 2020 at 5:41 PM
    #3
    JohnLakeman

    JohnLakeman [OP] Burning Internet Daylight

    Joined:
    Feb 21, 2019
    Member:
    #26430
    Messages:
    2,310
    Gender:
    Male
    Outside of Weird, TX
    Vehicle:
    2017 MGM DC TSS 4.6L
    TRD Pro grille, 2018 LED Headlights, Undercover Flex bed cover, Neoprene seat covers, Bed/tailgate mats, Power tailgate lock, auto headlights, illuminated key switch
    Part 2: Install Cooler-Pipe-Assembly (Part Number 32907-0C040) was covered in this thread:
    https://www.tundras.com/threads/add...ra-for-under-400-–-part-1.77739/#post-1972632

    Warning: This thread series (Parts 1-4) is written for 4.6L Tundra owners with little knowledge about retrofitting an auxiliary transmission fluid cooler to a truck that never had one. It is necessarily long and detailed to inform those owners.

    Disclaimer: This thread (Part 3) applies specifically to adding a transmission fluid cooler to 4.6L Tundras with A760 transmission. Toyota part numbers mentioned herein apply uniquely to 4.6L Tundras. The process is similar for the 5.7L Tundra, but IMPORTANT PART NUMBERS ARE DIFFERENT.

    Part 3: Install Transmission Thermostat (Part Number 32971-34030)

    Inspection of the passenger-side of 2014-2019 4.6L Tundra transmissions reveals an adapter-spacer plate mounted to the transmission near the front bell housing with an original equipment fluid warmer attached. The purpose of the fluid warmer is to quickly heat the transmission fluid to engine coolant temperature in order to reduce friction inside the transmission for improved fuel economy.

    Under heavy loading, such as towing, transmission fluid temperatures can exceed allowable limits resulting in rapid degradation without an auxiliary fluid cooler. To retrofit a transmission fluid cooler to Gen3 4.6L Tundras, the OEM 2010-2013 design of replacing the adapter-spacer plate with a Toyota transmission thermostat, PN 32971-34030, is followed.

    2010-2013 4.6L Without ATF Cooler.jpg
    2010-2013 4.6L With ATF Cooler.jpg

    Installation of the transmission thermostat is begun by first removing the adapter-spacer plate.

    Remove Adapter-spacer Plate

    (1) Compress the spring hose clamp tabs on both ends of the transmission fluid hoses to the adapter, and relocate the clamps further onto the hoses. Insure that the clamps are well past the hose barb ends of the connection nipples. Loosen the three bolts (12mm) attaching the adapter to the transmission, then loosen the three bolts (12mm) attaching the fluid warmer to the adapter.

    Hose clamps.jpg

    (2) Remove the three bolts attaching the warmer to the adapter, and gently separate the warmer from the adapter. You can expect a few ounces of transmission fluid to leak out of the warmer when the joint is separated.

    IMG_0621.jpg
    IMG_0630.jpg

    (3) Remove the three bolts attaching the adapter to the transmission. Push the adapter plate forward toward the engine, pushing on the hose ends at the transmission, until the fluid hoses are free of the transmission hose fittings. Remove the adapter-spacer plate.

    IMG_0631.jpg

    Install Transmission Thermostat

    (4) Pre-assemble the hoses and hose clamps onto the thermostat, insuring that hoses are seated fully to hose stops, and that the hose clamps are positioned between the hose stops and the hose barbs.

    IMG_0640.jpg T.jpg

    (5) Hold the thermostat in position with the machined o-ring contact surfaces toward the warmer, and install the transmission fluid hoses to the transmission fittings. Seat the hoses to the hose stops, and properly position and re-install the hose clamps. Re-install the three bolts removed from the adapter finger-tight to hold the thermostat in position.

    IMG_0634.jpg

    (6) Install cooler inlet hose, PN 32941-0C040, to the inboard tube-end of the cooler-pipe-assembly installed in Part 2. Install cooler outlet hose, PN 32942-0C050, to the outboard tube-end of the cooler-pipe-assembly. Seat hoses fully against the hose stops, then release and properly position the hose clamps. You won’t need to come back here, except to visually inspect for leaks.

    (7) Remove any sealing tape (if used) from the transmission thermostat. Inspect the mating contact surfaces of the thermostat and fluid warmer to insure mating surfaces are clean of any foreign matter, and that the two sealing o-rings are still correctly positioned in the o-ring grooves. Position the warmer against the transmission thermostat, and install the three warmer bolts finger-tight. Typically, the o-rings would be replaced. In this case, the o-rings were relatively new and were reused. Two spare o-rings were available in the event the o-rings were damaged.

    (8) Torque the three transmission thermostat bolts (12mm) to 15 ft-lbf. Torque the three warmer bolts (12mm) to 10 ft-lbf. I found it impossible to use a torque wrench on these fasteners. As indicated before in Part 2, you will have to resort to the “tongue-in-cheek” method of approximating the actual torque. The torque values are only given here to provide a level of cautionary discretion.

    This completes the installation of the transmission thermostat. Leave the factory-installed pin in the thermostat until the transmission fluid level has been finally adjusted at the proper setting temperature.

    Part 1 Bill of Material: $87.81
    Part 2 Bill of Material: $87.49
    Part 3 Bill of Material: $167.34
    • (1) Transmission thermostat, PN 32971-34030, $108.39*
    • (1) Cooler inlet hose, PN 32941-0C040, $22.84*
    • (1) Cooler outlet hose, PN 32942-0C050, $26.55*
    • (4) Hose clip, PN 90466-16004, 4 @ $2.39, $9.56*
    Total Cumulative Cost: $342.64

    Other Expenses:
    • (2) O-Ring, PN 90301-20012, 2 @ $3.00, $6.00*
    * Prices from Toyota of Cool Springs, September, 2020

    Part 4: Adjust Transmission Fluid Level is covered in this thread: https://www.tundras.com/threads/add-oem-style-transmission-cooler-to-your-4-6l-tundra-for-under-400-–-part-4.77888/
     
    Last edited: Nov 10, 2020
  4. Nov 7, 2020 at 5:41 PM
    #4
    JohnLakeman

    JohnLakeman [OP] Burning Internet Daylight

    Joined:
    Feb 21, 2019
    Member:
    #26430
    Messages:
    2,310
    Gender:
    Male
    Outside of Weird, TX
    Vehicle:
    2017 MGM DC TSS 4.6L
    TRD Pro grille, 2018 LED Headlights, Undercover Flex bed cover, Neoprene seat covers, Bed/tailgate mats, Power tailgate lock, auto headlights, illuminated key switch
    Part 3: Install Transmission Thermostat (Part Number 32971-34030) was covered in this thread: https://www.tundras.com/threads/add-oem-style-transmission-cooler-to-your-4-6l-tundra-for-under-400-–-part-1.77739/#post-1974341

    Warning: This thread series (Parts 1-4) is written for 4.6L Tundra owners with little knowledge about retrofitting an auxiliary transmission fluid cooler to a truck that never had one. It is necessarily long and detailed to inform those owners.

    Disclaimer: This thread (Part 4) applies specifically to adjusting the transmission fluid level of 4.6L Tundras with A760 transmission. The fluid level adjustment process is similar for the 5.7L Tundra (AB60 transmission), but REFILL PORT LOCATION and SPECIFIED TEMPERATURE RANGE are DIFFERENT. Refer to other sources for 5.7L transmission fluid level adjustment procedure.

    Part 4: Adjust Transmission Fluid Level

    Confirm Fluid Hose Identity

    After the trans-cooler system installation is complete, you can elect to confirm the identity of the hot fluid supply pipe/hose as discussed in Part 2. That should occur as a first step in adjusting the transmission fluid level. If you do not plan to do the test, add one quart of ATF WS fluid as discussed below, and then skip down to Adjust Transmission Fluid Level.

    Some additional fluid volume will be lost from the transmission during the test, and that will be additive to the extra volume from the thermostat, cooler pipes/ hoses, and the trans-cooler. For making this test, the two hose connections at the trans-cooler should have been intentionally left disconnected.

    Add Transmission Fluid

    Before doing the test, the transmission should be pre-filled with one quart of ATF WS fluid. Assuming the transmission fluid level was correct to begin with, one quart should be enough fluid to fill the additional system volume that’s been added, plus some minimal fluid loss during the test.

    On the 2WD A760E transmission, the Refill Port is located on the passenger side of the tailshaft housing. Fluid will need to be pumped into the Refill Port opening using a large purpose-specific syringe. Capacity of the syringe shown below is 3/8 quart (12 ounces), which will work fine for adding one quart, not as well for several quarts. The Refill Port plug requires a 23mm socket, but standard 15/16” socket will also work perfectly.

    Fluid Addition (2).jpg

    The Refill Port plug is easily accessible with a torque wrench. You can leave the Refill Port plug finger-tight until all fluid level adjustment is complete, then it should be torqued to 29 ft-lbf.

    After one quart of ATF WS has been added to the transmission, the tube/hose identity test can be done. Have a helper sit in the driver seat, and instruct them to start the engine when signaled, then to be prepared to shut it down immediately on signal. Hold a five gallon bucket or similar large container under both fluid hose ends at the trans-cooler, and have the helper start the engine.

    The engine will likely start at fast idle. It will seem like nothing is happening for several seconds (7-10?), then one hose will begin flowing rapidly. Immediately have the helper shut off the engine since you’re emptying your transmission of fluid. The hose that flowed is the hot fluid supply hose that connects to the lower trans-cooler hose barb. Connect both hose ends to the trans-cooler in turn, and install the hose clamps.

    Adjust Transmission Fluid Level

    The final step in retrofitting an auxiliary transmission fluid cooler to your 4.6L Tundra will be adjusting the transmission fluid to normal operating level. Fluid level adjustment must be done with the truck on a level surface, and with transmission fluid temperature within a specified range (127-138 degrees for A760). Your newly installed transmission thermostat should also still have the factory pin in place for fluid level adjustment.

    Instructions in the Repair Manual for jumpering DLC3 terminals 4 to 13, and moving the shift lever in a certain sequence, within a required amount of time, can be intimidating. My recommendation is to just simply cut through the bs, and use a corded ScanGauge, or Blue-tooth/WiFi OBD2 device app (UltraGauge, OBD Fusion, Torque Pro) to read the transmission fluid temperature directly.

    IMG_2089.jpg

    This one change will make transmission fluid level adjustment a simple, easy procedure. When you are under the stress of having to quickly get under the truck to remove that level-checking Overflow Plug (5mm hex), the novice doesn’t need to waste time looking for blinking/non-blinking dash lights.

    Overflow Plug (2).jpg

    Reading the actual fluid temperature at the intended level-checking location (thermocouple) by OBD2 will be accurate within tenths of a degree. You may not be able to read that much accuracy on your OBD2 device, but you will be able to read to the nearest degree IF you have the PIDs set up correctly. To wit, if you want the level to be accurately set, the temperature used for setting the level has to be accurate.

    For that reason, I recommend checking the calibration of your device before-hand using the written level adjustment procedure in the Repair Manual, without actually removing the Overflow Plug. If you don’t have the Repair Manual, I have personally posted the procedure here; it’s available for the search.

    You can also use an inexpensive infrared non-contact thermometer for a degree of redundancy and confirmation. Ideally, the non-contact thermometer should also be calibrated against a precision dial thermometer. When I compared my non-contact thermometer against a precision dial thermometer, I found the non-contact thermometer off by about three degrees.

    After all that, you’re probably asking, “Why not just use the non-contact thermometer in the first place?” I didn’t for several reasons: First, there’s the calibration problem already discussed. The level checking temperature range is only eleven degrees (127-138 degrees). If your non-contact thermometer is off by 5 degrees, that’s almost half the allowable level-setting range. Second, I discovered during this process that pan temperature may vary as much as 3-5 degrees as you move the non-contact thermometer pointer around on the pan surface. Remember that the temperature Toyota wants for fluid level setting is AT THE THERMOCOUPLE.

    The trans-cooler, thermostat, and fluid tubes/hoses were found to add approximately 20 ounces additional fluid volume to the transmission and trans-cooler system. Theoretically, one additional quart of ATF WS will be enough fluid to complete this level adjustment, but having at least two quarts on hand is recommended. If you elect to do the tube/hose identity test discussed in Part 2 and earlier, you may need more than two quarts fluid depending on your helper’s reaction time in shutting off the engine.

    I added a total of 44 ounces of fluid to my transmission in two stages. After completing the trans-cooler system installation, I added one full quart of ATF WS to the Refill Port on the tailshaft housing of my A760E transmission. Total fluid loss during the test was 12 ounces. Later, after adding another 12 ounces of fluid from a second quart, I learned that the fluid overflow from setting the correct level at 129 degrees was exactly…12 ounces!

    At that time, I was unaware that the added volume from the cooler installation was about 20 ounces. Had I known, I would have done what I am recommending here: Before adding any more than one quart of fluid, start the engine and bring the transmission up to level check temperature (127 degrees) with the truck on a level surface. Immediately remove the loosened Overflow Plug to determine if you have any overflow. If you already have a vigorous trickle, I would quickly reinstall the Overflow Plug and torque it to 15 ft-lbf (180 in-lbf). Then, torque the Refill Plug to 29 ft-lbf. Stick it with a fork, it is done.

    If there is no overflow, then you’ll need to add fluid until it does overflow. Given the dynamics of changing fluid temperature, this may be better done after the transmission has cooled. Add amount of fluid you feel necessary, replace the Refill Plug finger-tight then start the engine. Bring the transmission fluid temperature up to 127 degrees, and remove the Overflow Plug to check for overflow. When the flow has declined to a vigorous trickle, replace the Overflow Plug, torque both Overflow Plug and Refill Plug. Now, you’re really done.

    One other thing: Don't forget to remove the thermostat pin before you roll out from under. Keeping the pin in a safe place for future fluid level checking will be a good plan.

    Part 1 Bill of Material: $87.81
    Part 2 Bill of Material: $87.49
    Part 3 Bill of Material: $167.34
    Part 4 Bill of Material: $25.12*
    (2) Toyota ATF WS, 2@$12.56

    Total Cumulative Cost: $367.76

    Other Expenses:
    (1) ABN Fluid Transfer Syringe, $29.99*

    * Prices from Amazon

    https://www.amazon.com/gp/product/B007WMF0Q8/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1
    https://www.amazon.com/gp/product/B075NKV4CR/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
     
    Last edited: Nov 12, 2020
    Saltyhero13 likes this.
  5. Nov 8, 2020 at 7:28 AM
    #5
    Ruggybuggy

    Ruggybuggy New Member

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    Dave
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    Very good detailed write up!

    We should make this thread a sticky when your done.
     
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  6. Nov 8, 2020 at 9:16 AM
    #6
    JohnLakeman

    JohnLakeman [OP] Burning Internet Daylight

    Joined:
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    2017 MGM DC TSS 4.6L
    TRD Pro grille, 2018 LED Headlights, Undercover Flex bed cover, Neoprene seat covers, Bed/tailgate mats, Power tailgate lock, auto headlights, illuminated key switch
    Thanks @Ruggybuggy, much appreciated.

    I borrowed from you and others that have gone before. @salmonator made this retrofit to his 4.6L a couple of years ago, but I couldn't find his write-up. I wanted to document the details of the entire process for other 4.6L owners. The retrofit seems complicated, but it's really not. It just takes a lot of text and pics to explain it all. Part 2 coming soon.

    If the mods think this information is worth a sticky, it would be nice to have it on top of the heap for 4.6L owners that tow. :thumbsup:
     
    Ruggybuggy likes this.
  7. Nov 9, 2020 at 6:50 PM
    #7
    Johnsonman

    Johnsonman New Member

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    Sequoia
    LED headlamps/fogs; interior footlamps.
    If it cost Toyota anywhere this much to build this into the 4.6 & 5.7 no wonder they dropped the feature. I guess the base cooling is adequate per their engineers and lawyers. Good write up!
     
    JohnLakeman [OP] likes this.
  8. Nov 9, 2020 at 9:16 PM
    #8
    JohnLakeman

    JohnLakeman [OP] Burning Internet Daylight

    Joined:
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    Male
    Outside of Weird, TX
    Vehicle:
    2017 MGM DC TSS 4.6L
    TRD Pro grille, 2018 LED Headlights, Undercover Flex bed cover, Neoprene seat covers, Bed/tailgate mats, Power tailgate lock, auto headlights, illuminated key switch
    After months of discussion here, I'm confident there will never be a consensus on Tundras.com about Toyota's willingness to gamble with their reliability reputation. Like oil and filter threads, I won't even read threads arguing the reasons for needing or not needing transmission coolers. I've made my decision based on likely length of ownership (forever) and potential for future application (possible towing).

    The bottom line is, Toyota managers can afford to be confident about their decision, but after the powertrain warranty expires in 19 months, I'll own the risk. Clean fluid samples captured during this retrofit already appeared slightly darkened; still fine for service, but not appearing "new". That's after 5200 miles and one three hour tow. My last Toyota truck I kept for 31 years. If I ever have to tow with this truck again, it's the prudent decision and cheap insurance for me.
     
    Last edited: Nov 9, 2020
    Ruggybuggy likes this.

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