How much engine temperature fluctuation?

What type of engine temps are you seeing? I have the 3.5 auto and am pretty heavy.
I see mine fluctuate between 186 - 202 all the time. While I am driving. For no apparent reason. It does not matter (much) if I am going up, down, or flat. It will vary between these numbers nearly constantly. It will hold sometime for a couple min, but then it will vary again. I am using a scan gauge II to monitor.

Makes me want to put in a new thermostat... 22K miles.

 

Engine temperature fluctuations are completely normal. They can change based on load, ambient temperature, air flow across the radiator, heat load from the other sources (trans, pw steering). The sensor isn't always as accurate either. It can fluctuate too.

Another thing to note is thermostat operation... the set temperature is the point that the thermostat starts to open. And then it it will open and close as needed to maintain that temperature point.

I wouldn't worry too much about the temperature reading and be more aware of the signs of true heat shedding issues, like the fan clutch engaging when clearly not required or coolant boil over. There is a reason the temperature gauge on the dash doesn't have numbers, makes people worry unnecessarily.

 

Yes, I see the same temps on avg. V6/Auto. Using OBDII and TorquePro.

 

I see the same on my Scan Gauge II.

 

Sounds perfectly normal to me.

 

engines never run at the same temp. They run within a range of temps.

 

Yep, up and down through the drive. Same with oil temps, ATF1 and ATF2..

sometimes the scanguage can drive you crazy..

 

IIRC 3rd Gen Taomas do not have an oil temp sending unit, only oil psi. How did you get your setup to see oil temps?

 

it’s derived by the ecu. If you look at the charts it follows close to what the atf is doing..

 

You want to put in a new thermostat because it's functioning as intended?

The internal combustion engine that powers your truck harnesses a small explosion in each cylinder. Said explosions produce heat.

The cooling system, that came factory on your truck, cools the engine down.

With your given values, when the temps are 184°F or below, the cooling system turns off. When it reaches 202°F, cooling system turns on and brings the temps down to 184°F or below. This cycle repeats over and over.

180°F-210°F is a very normal operating temperature range. If you're 215-220°F+, you might have a problem.

 

this is why the MFG's get rid of gauges (aside from costs) and the ones they kept, they changed how they react to changing values.
it's fine

 

normal

 

Toyota OEM temp gauges never move perceptably from normal unless something is really wrong. This has been true since the 1993 pickup before the Tacoma name even existed, and when it moves, it gets your attention quickly. The only time I've ever seen it was when I had a top hose collapse during a heatwave in the mountains.

On my 01 and my 15, it has never moved from normal, even in mountains towing.

This is why people buy Toyotas.

Obsession with trivial data and screens just distracts your eyes from the road. The only reason to monitor stuff at that level of detail is for things like AT temp when towing or perhaps when supercharged for diagnostic fuel trim needs.

 

Thats nothing. My 2002 Eurovan fluctuates from 180-220 and the needle never moves, it's at the 12 o'clock position all day every day.

You're fine, don't worry about it

 

ooooooohhhhhh hang on a minute. My bad.

This is the 3rd gen forum.

Watch that scan gauge like a fuckin hawk.

 

I'd only be concerned if it got up to 230 degrees and didn't drop back down. You're good no problems there.

 

TF1 and TF2 codes on Scangauge 2. TF2 is pan temp, and TF1 is entering pan, or something close to this. TF2 is fairly stable...TF1 fluctuates between a range of like 183 to 217-ish on mine.

Good check to see that everything is working: as TF2 goes up, so does Coolant Temp. Then, and coolant temp goes down, so does TF2. Rinse and repeat throughout trips.

 

TF is transmission, right? I was referring to engine oil temp.

 

Measuring things is always dangerous. Its not just about what the safe operating range is, but what is considered to be a significant deviation from that range, is there a timed acceptable range of x degrees for y seconds, what is the significant deviation for that, what resolution our measuring device has, is the resolution/response linear or curved or logarithmic, when was it last calibrated against a known standard, how often does it need to be calibrated, what is the rate of calibration drift, what is the sampling rate, is the sampling rate sufficient, what is the resolution of the readout, is it different than the measuring device, what is the rounding error, what difference between measurement and readout is considered significant... and so on.




I'm a fan of if the car starts and there is no visible fire, then car is good.

 

Paragraph 1 is one definition of "analysis paralysis". "Analysis paralysis" prevents you from just doing the task at hand ... driving.