A750F Transmission & ScanGauge II - What are your temperature readings? (1 Viewer)

[94SRUNNER]

I thought I would update this as I was able to get some good data during a trip I took to Milwaukee and back over the last two days. We are in the midst of a heat wave in the mid-west and day time highs are in the mid-90's. During my drive we had ambient temps in the mid-80's to the upper 90's and this trip was primarily highway driving. Trans temps range from ~135-148* and stayed around 145-148* during most of the drive and coolant temps range from 186-191*, with the AC running the whole time. During slow or stopped traffic (such as in Chicago) transmission temps would climb into the upper 150's.

 

[flintknapper]

I thought I would update this as I was able to get some good data during a trip I took to Milwaukee and back over the last two days. We are in the midst of a heat wave in the mid-west and day time highs are in the mid-90's. During my drive we had ambient temps in the mid-80's to the upper nineties and my this most recent trip was primarily highway driving. Trans temps range from ~135-148* and stayed around 145-148* during most of the drive and coolant temps range from 186-191*, with the AC running the whole time. During slow or stopped traffic (such as in Chicago) transmission temps would climb into the upper 150's.

Almost exactly what my A343F does. Good to know we are in the same parameters. Thanks for the info.

 

[NoTempoLimit]

I have not seen anything above 150ºF on my 2006 LC (no towing). These low trans fluid temps are probably the reason why Toyota does not put ATF oil changes in the "regular service" maintenance schedule.

I still think not changing the fluid at all is a BIG risk. Even at 150ºF the fluid is going to degrade eventually, additives get depleted, and the filter needs changing. Also, fluid tends to seep past the gaskets slowly, so eventually you will run low on ATF fluid.

So the right interval is somewhere between Toyota's severe service 60k mi and 100k mi (which is what BMW quietly ended up reccomending after getting sued for "lifetime fluid" causing transmission failures just out of warranty).

 

[94SRUNNER]

Time for another update. I was able to get some good data during our 12 day/2500 mile road trip I took to Pewaukee Lake, WI, St. Paul, MN, Fargo, ND, the Iron Range in MN, Duluth and Carlton MN and back to Dayton, OH. We had really pleasant weather during the coarse of the trip we had ambient temps in the upper 70's to mid-80's, with the exception of our time in Fargo, ND when the temps were in the upper 80's to mid-90's. This trip was primarily highway driving. Trans temps range from ~131-145* and stayed around 135-140* during most of the drive and coolant temps range from 186-188*, with the AC running the whole time. On long grades temps would hit 190-191*, but only for short periods and trans temps never climbed much out of the previously mentioned range. During slow or stopped traffic (such as in Chicago) transmission temps would climb into the upper 150's and low 160's.

 

[94SRUNNER]

I figured I update this as we finally had some warm weather, with ambient temps in low 90's and the sun was shinning. The kids and I drove to my folks house about 40 miles away. Trans temps range from ~131-150* and stayed around 135-147* during most of the drive and coolant temps range from 188-190*, with the AC running the whole time. On long grades temps would hit 190-191*, but only for short periods and trans temps never climbed much out of the previously mentioned range. On one of the steeper and longer grades (~300-ft over 2 miles) the coolant temp briefly hit 195* while cresting the top, but quickly dropped and tranny temp never fluctuated from the norm

 

[NoTempoLimit]

I've been running Scan Gage II reading temps on my A750F for over a year now. Thanks to the code posted on this forum. I too have never seen any high temperatures. Normal is 125 - 135ºF, never anything about 150ºF, but there are no long grades here and I don't tow.

This is probably where the idea of the "forever" ATF fluid comes from. But even though thermal breakdown is not an issue, the ATF would gradually degrade over time due to oxidation, moisture, etc, and gaskets leak causing the fluid volume to go down.

I'm still thinking around 60k mi interval for the next fluid change (about 2/3 way there).

 

[Red Beard]

Sitting in traffic on the Chesapeake Bay Bridge toll plaza this past weekend at 98°F Ambient temp, my temps were AT: 160°F and Coolant; 201°F.
But that was max for my whole trip. On the highway and around town, my temps are normally AT: 123°F, Coolant: 196°F.

I got a little fuel smell in the cabin while sitting there as well, so I'm afraid I got a little fuel boil issue in that heat.