transmission temperatures

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Jan 3, 2010
Abbotsford BC
just wondering what people are getting for transmission temperatures. I'm driving a 1990 HDJ81 and after about 30 minutes of stop and go driving i can get up to 180 degrees. I'm probably going to install a aux tranny cooler since the HDJ81 didn't come with one but i'm curious if my temperatures are abnormal.
Mine can climb as high as 180 in stop and go, or wheeling, however, I think that is well within the normal operating range. From what I understand, running a cold trans can be just as bad as running an overheated trans. I'm not sure what your HDJ81 has, but the OEM trans cooler on the FZJ works really well.
According to the 96 FSM as well as most ATF temperature charts I have ever seen, 70-80C (158-176F) is the ideal operating temperature range for ATF. Mine climbs to 70 within 15-20 minutes of non freeway driving. It will rise to 80 (176) in traffic, offroad, or towing a trailer. When the torque converter locks up during highway cruising, the temp can drop to 65 or 60 (149 or 140).

Your temperatures sound pretty normal.
Here in the middle east I routinely run over 200 degF sump temp in my 1993. 225 in extreme heat and stop and go traffic. I am running an Autometer 3657 gauge and sender installed in a welded bung in the pan.

I'd say you're in pretty good shape at 180 degF.
OK my temps sound pretty average then, i was just surprised how fast it climbed in 30 minutes of driving. I'll try some freeway driving and see what happens when the TC locks up. so whats the max temperature i should let it get to before having to stop and let it cool down??

This is a pretty common bar graph of ATF lifespan vs temperature.
so whats the max temperature i should let it get to before having to stop and let it cool down??

I start feeling un comfortable after 210°F never happen to me but I thought I will never let it go over 230°F coz that means something isin't right as it should .. that's just my opinion ..
My gauge starts at 150 and reads sump temp and the only time I've ever seen it go above something like 160 is when I was pulling a truck with a tow strap up a steep off road trail at moderate engine load, low speed. It got up to about 200 then.

I don't tow so I can't speak for highway towing temps, but I've never seen it go above 160 sump temp, regardless of how hot it is outside, road conditions, etc. I'm guessing the two factory 1FZ tranny coolers do their job and then some. Seems like the Toyota Aisin transmissions run much cooler and better and therefore, for much longer periods of time than other makes out there.
I have a 17 foot travel trailer that we towed in the summer up some fairly steep mountain passes here in BC. I have installed a VDO tranny temp gauge ( of course using info form this forum!). It's range is 120 to 300 (I think). The hottest that I saw was about 200 during some of the long climbs.

While off roading, slow, up hill it will get up to 180 or so.

No load cruising is usually around 130.

All in all I think that the factory set up with the 1FZ engine is very good. I did also own an HDJ81 previous to this truck. I think that the HDJ81 would definitely benefit from an after market tranny cooler. Also a good gauge is a great piece of mind.

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