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TundraGeneral discussion forum for the 2007 and later Toyota Tundra.
This is a discussion thread titled "Automatic transmission oil heater - cooler", within the Tundra forum, part of the Truck Forums category.
Has anyone figured out the 5.7 6 speed trans oil heater then cooler? Is there a bypass system that heats the trans oil only when the oil is cold and then bypasses the heater and sends the oil to the trans cooler when the oil is hot? Where is the trans heater located? Can you bypass the trans oil heater in never cold southern California and cool the auto trans too much?
You would not want to remove the transmission fluid heater even in southern Cali. It helps get the transmission up to operating temps quicker which in turn helps mileage and reduces wear by getting the fluid to optimal viscosity.
Once the tranny is up to temps there is a check valve that stops the flow of warm fluid going to the tranny heater. It then opens the way for the tranny fluid to flow through the cooler.
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2007 Tundra 5.7 6-spd 2wd
Silver, double cab, short bed
TRD package
"Models with ATF Cooler
When the ATF is at a low temperature, it is warmed up by the engine coolant in the ATF warmer.
When the ATF is at a high temperature, it flows to the ATF warmer and then to the ATF cooler, thus it
is cooled down."
ATF = Automatic Transmission Fluid
The overheated fluid would be bypassed by the thermostatic valve to the cooler then back to the transmission.
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Beer please!
Unknown - "The biological purpose of pain is to prevent the recurrence of stupidity."
So is that showing that the engine coolant is always flowing through the "transmission heater"? Is that a good thing or a bad thing? Like what if the transmission is at the proper operating temperature, but the engine is overheating? Like say you were in stop and go traffic in the summer with A/C on. Could the engine coolant be overheating the transmission fluid? Which fluid would be at a higher temp under normal conditions? I would assume the engine coolant coming straight from the engine and before the radiator.
You don't need to worry because Toyota coolant and transmission oil temps stay relatively low even during stressfull congested city traffic or long hill climbing conditions.
Example: Normal Toyota coolant temp = 180 degrees. In stressful conditions it rises to 195 -205 degrees. Normal Toyota transmission oil temp: 120-150 degrees. Stressful fluid temp: 160-190 degrees
Chevy Normal coolant temp = 195 degrees. In stressful conditions it rises to 220 degrees. Normal Chevy transmission oil temp: 180-200 degrees. Stressful fluid temp: 210-240 degrees.
Now you also know how GM builds planned obsolesence into it's vehicles (by slowly roasting them to death).
mxsjw: Thanks for the TSB on the Trans refill procedure. Now I have something else to worry about! If the dealers have so much problem changing the engine oil in the Tundra, can you imagine what they will do the first time you bring it in for transmission service?! I hate to even think about it! Plus, the Tundra takes ATF WS fluid, not the usual ATF Type T-IV fluid...think they will use the right fluid?? Or follow the step by step procedures outlined in TSB 009-07???
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'07 Tundra SR5, 2WD DC, 5.7L, Salsa Red Pearl with Running Boards, Delta Toolbox.
According to the ScanGauge, the Tundra 5.7 engine coolant, at normal operating temp, is +/-200F, not 180F, and this is with no load. Seems odd that the tranny fluid would be heated to +/-200F and then cooled to whatever temp by the cooler. Oh well, I'm sure Toyota knows what they're doing.
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'07 RCSB 5.7L SR5 Silver Sky Metallic (The Silver Bullet) Yep....it's gotta HEMI
Never argue with an idiot. They will bring you down to their level and beat you with experience!
It states in the TSB that to check fluid level the fluid should be between 115 & 133 degrees F. Where do you see that the Tundra trans temp is +/-200 degrees??
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'07 Tundra SR5, 2WD DC, 5.7L, Salsa Red Pearl with Running Boards, Delta Toolbox.
It states in the TSB that to check fluid level the fluid should be between 115 & 133 degrees F. Where do you see that the Tundra trans temp is +/-200 degrees??
......................Where do you see that the Tundra trans temp is +/-200 degrees??
I don't know for sure that the tranny fluid actually reaches +/-200F before being cooled by the tranny cooler, however the engine coolant that flows through the tranny fluid WARMER is +/-200F at normal operating temp.
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'07 RCSB 5.7L SR5 Silver Sky Metallic (The Silver Bullet) Yep....it's gotta HEMI
Never argue with an idiot. They will bring you down to their level and beat you with experience!
I don't know for sure that the tranny fluid actually reaches +/-200F before being cooled by the tranny cooler, however the engine coolant that flows through the tranny fluid WARMER is +/-200F at normal operating temp.
The thermostatic valve is controlled by the temperature of the ATF not the coolant. The ATF warmer ceases to function once the ATF is at operating temps.
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2007 Tundra 5.7 6-spd 2wd
Silver, double cab, short bed
TRD package
The thermostatic valve is controlled by the temperature of the ATF not the coolant. The ATF warmer ceases to function once the ATF is at operating temps.
Wrong...........the fluid flows to the warmer whether it is hot or cold. If it's hot, it flows to the warmer, then to the cooler.
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'07 RCSB 5.7L SR5 Silver Sky Metallic (The Silver Bullet) Yep....it's gotta HEMI
Never argue with an idiot. They will bring you down to their level and beat you with experience!
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Automatic transmission oil heater - cooler
Oh well, I'm sure Toyota knows what they're doing.
Linear Mode
