Consolidated Operating Temperature Thread (1 Viewer)

[e9999]

This weekend I did some monitoring of my temperatures with an OBDII scanner.

Traveling down highway 99 my temperature read 212-214 while traveling at 65-70mph with a roof rack and roof mounted tent. Outside it was probably 90-95.

Going uphill into the Sierras I reached a maximum temperature of 221 going 55 mph in 3rd gear. Going down to 2nd gear reduced the temperature to 214.

While offroad in 4lo my temperature never went over 200, even when climbing.

With the new modifications to my temperature gauge, 221 read at about 2 needles widths below the red line. 214 was at about the 3/4 mark.

Except for the freeway one, which is much higher than mine, these are all very close to temps I've seen. And I don't think the latter are abnormal.


LT, FWIW, I monitored my ATF temps at the same time as the coolant ones, and the ATF was always cooler than the coolant, sometimes by as much as 50F or so, even long after warmup.

 

[Rich]

..I'll also post my formula for determining R2 given R1, the diode replacement, and voltage across inductor 3 (I think that's the right number).

Thanks for the info!

 

[landtank]

LT, FWIW, I monitored my ATF temps at the same time as the coolant ones, and the ATF was always cooler than the coolant, sometimes by as much as 50F or so, even long after warmup.

That's good to know.

The rest was deleted because I'm an idiot and got the direction wrong. The flow is to the radiator and then on to the aux cooler and the temp sensor is on the ouput side of the tranny.

 

[e9999]

That's good to know. With the help of another member we confirmed the flow of the ATF and it does go to the cooler first and then the radiator. I was real nervous when the truck was running hot on me that the tranny was seeing damage. When I checked my tranny fluid at that time it was noticeably a lot warmer than it has ever been before.

That sensor on the tranny is actually on the return side of that loop. You would be able to get a good idea of how well your cooling system is working by comparing the running temps of your truck to that of that sensor I think. The larger the difference the better the cooling.

I put my sensor on the line that leaves the tranny for the cooler. May be underestimating things a bit because it's a metal line and the TC is on the outside -although insulated- but should be in the right ballpark. That skinny metal line probably helps to cool the ATF quite a bit too.

The ATF temp varied quite a bit more than the coolant temps also, which is why it could go back down fast at times. When climbing a steep dirt road at low speeds under 100F weather I could be up to 220F coolant / 210F ATF but when I'd go back to a flat highway after that, it may go back to 190/140 in a pretty short time.

 

[cary]

I'll start:

1) 1996 Stock engine 6 degrees of advance on the timing.

2) Raventai Mod.

3) Fan clutch (factory blue), thermostat and 1993-94 radiator replaced in the past week.

4) Toyota red coolant 50/50 with distilled water and 1/3 bottle of redline diesel water wetter (same as regular water wetter without the corrosion inhibitors).

6) Prior to cooling system replacement. Long uphill climb, 3/4 throttle, 3rd gear 2800 rpm, 215f before backing off in 75-80f weather. 210f in stop and go and idling at 85 f. 200f at 70mph heating to 210f at 80mph in 85f weather. All with A/C on.

Now: 17% grade 3/4 mile climb after exiting freeway (first gear climb) 205f in 92F weather (test previously aborted). Freeway 195f top at 80mph in 92f weather. Idling at drivethrough 200f. All with A/C running.

7) 215f before, 205f after new parts.

8) I would guess that 217f-220f would be a safe operating temp given that is where the A/C comes back on if the truck has gotten too hot. I remember most older cars had a 220-230f as a starting point for the red zone. I think it is reasonable to expect to see 200-205f on a regular basis in 80f+ weather.

Update to my operating temps. I drove from the bay area up through Sacramento and to the Sierra Foothils (El Dorado Hills) yesterday. Temps ranged from 95 in the Bay Area to 103 up through Sacramento and El Dorado Hills. Running at a constant 80mph, I saw temps of 190-195 on the flats. Climbing a third gear grade, full throttle for 1-2 minutes produced a steady 200-205f. The highest temps I saw were when pulling off the freeway and pulling straight into a drive though. Total idle time was about 10-12 minutes. During that time the temp climbed to 210-215f.

While sitting in the drive through, I put it in neutral when it was at 210-215f and reved it up to 2000rpms. You could clearly feel the heat comming back from the fan, but it was also clear the fan clutch was not fully locked up as there was sound from it, but nothing even close to the startup roar (it is a two week old blue OEM).

So with a fresh radiator and stock fan clutch, 215f is not out of the question. Given that it stayed cool on the freeway, I believe a more agressive fan clutch would have kept it at 200-205f while idling.

 

[Hollis Cameron]

did a lot of temperature monitoring and fooling around with the A/C yesterday on the trail and freeway.

One observation: if the engine is getting hot, go down in gears. It's very effective, especially on the ATF side I think.
I was going slow on a dirt road in 100F weather, loaded. When going slowly up some steep slope, if I were in D, at times I would be up to 220F for coolant and up to 210F for ATF. But when I switched to 4Lo, the temps would drop to 205 / 180F. Presumably due to increased circulation plus higher fan speeds.
Obvious, but easy to forget, and wouldn't see that at all with the OEM gauge.

Basing myself on the a/c shut off, I would not be afraid at all to go up to 226 without stopping etc. For sure they put some safety factor in that 226F... And RT, it's perfectly fine for the Tstat to be fully open, that's taken into account in sizing the rad.

I found this as well. My obd2 guage gives me engine temp, rpm and engine load. To cool a hot engine you want low engine load and higher rpm. This will cool it down quickly. Gearing down does exactly this.