Measuring ATF Temperature

[cdr00777]

Very clever! Unfortunately no dip stick on this sealed tranny. However, I did think about possibly fishing my VOM thermocouple wire into the pan from the fill port but was concerned it might get snagged and I would be up the creek without a paddle.

I ended up using my voltmeter thermocoupler tie wrapped to the Dorman dipstick. The transmission was way overfilled, and only saw about 150F temp.
Not as true a read as in fwd gears or reverse with proper scan tool.
First check without thermocoupler just to see where oil was, when it came out probably 3/4" past the end of the marked dipstick. I removed 1 1/2 quarts and if I check it now it's 85-90 & temp at 150F.
So either that's one cool transmission or I need to get it scanned.

 

[The Critic]

I ended up using my voltmeter thermocoupler tie wrapped to the Dorman dipstick. The transmission was way overfilled, and only saw about 150F temp.
Not as true a read as in fwd gears or reverse with proper scan tool.
First check without thermocoupler just to see where oil was, when it came out probably 3/4" past the end of the marked dipstick. I removed 1 1/2 quarts and if I check it now it's 85-90 & temp at 150F.
So either that's one cool transmission or I need to get it scanned.

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Not surprised. A lot of transmissions do not get as warm as people think.

 

[cdr00777]

Not surprised. A lot of transmissions do not get as warm as people think.

I may take out another quart and check it again on the dipstick.

 

[JeffKeryk]

I just serviced the 2015 Mazda3 I found for my grand niece. Pretty easy; @The Critic gave me some advice. I use an ACE Hardware calibrated paint container to measure how much drains and use that as a base line for initial fill. Then I lowered car back to ground and drove it. The next day I removed the air filter box (2 10mm fasteners) but kept the top connected so the engine runs. Get the trans up to temp, 122* F, measured with a temp gun. Pull and read dip stick. Easy peasy.

3L drained; I expected a bit more.
Our pig heavy GS is next; it's more of a pain to service.

 

[sloinker]

I ended up using my voltmeter thermocoupler tie wrapped to the Dorman dipstick. The transmission was way overfilled, and only saw about 150F temp.
Not as true a read as in fwd gears or reverse with proper scan tool.
First check without thermocoupler just to see where oil was, when it came out probably 3/4" past the end of the marked dipstick. I removed 1 1/2 quarts and if I check it now it's 85-90 & temp at 150F.
So either that's one cool transmission or I need to get it scanned.

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What is that thermocouple designation? Looks like Red and ? Does the dipstick act like a heat sink and take a few minutes to stabilize? It's a great Idea which I may copy.

 

[cdr00777]

What is that thermocouple designation? Looks like Red and ? Does the dipstick act like a heat sink and take a few minutes to stabilize? It's a great Idea which I may copy.

An innova 3340a automotive tester, voltmeter with plenty of different cables for loads of applications.
The thermocoupler is Red and Grey tiny wires with "K type" thermocoupler.
Im pretty sure it worked for a good idea of trans oil temp, and know oil level was right on stick, however still the most accurate way is to get it scanned in drive or reverse.

 

[cdr00777]

What is that thermocouple designation? Looks like Red and ? Does the dipstick act like a heat sink and take a few minutes to stabilize? It's a great Idea which I may copy.

It didn't take long to stabilize.
I did a controlled test with 190F water in a pot and checked with five different cooking thermometers compared to thermocoupler on meter and all were with 5-10 degrees different.
So pretty happy it's close enough for me.

 

[sloinker]

It didn't take long to stabilize.
I did a controlled test with 190F water in a pot and checked with five different cooking thermometers compared to thermocoupler on meter and all were with 5-10 degrees different.
So pretty happy it's close enough for How is the junction attached? Did you drill a well? Thanks for the info.

 

[dumkid]

You underestimate how useful an IR thermometer is. You can find stuck thermostat, bad wheel bearings, how cold your a/c is, what temperature your lawnmower runs at, etc. Also most have a laser pointer built in so you can use it as a pointer if you want.

Also they're like $10

A scangauge is also a good tool. I want one but they expensive so if I feel the need i can use our Bluetooth scanner and my phone as a scangauge, or if I have to do vehicle specific stuff i can always drive around with the wired Autel and have someone else read me the numbers

 

[SHOZ]

When using a thermo lead and no access to the actual fluid, I would wrap it to say the atx oil cooling hose with tape or a tie, then wrap insulation around that. IR thermometers only measure the surface which will always be lower that what is heating it up.

 

[BrainThicknessVariation]

I ended up using my voltmeter thermocoupler tie wrapped to the Dorman dipstick. The transmission was way overfilled, and only saw about 150F temp.
Not as true a read as in fwd gears or reverse with proper scan tool.
First check without thermocoupler just to see where oil was, when it came out probably 3/4" past the end of the marked dipstick. I removed 1 1/2 quarts and if I check it now it's 85-90 & temp at 150F.
So either that's one cool transmission or I need to get it scanned.

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Do you even need to worry bout the fluid fill temp if you have a dipstick? I think OP was asking because newer Lexus' are "sealed" and folks are told not to touch the ATF.

However, should you need to mess with it for whatever reason, there is a particular method whereby you fill until the drain hole drips slowly, and this drip is engineered to occur when the ATF temp is at a particular level. I believe that with a paper clip, you can jump two pins at the OBD port by the drivers left knee, then there is a procedure where you toggle the gear shifter between D/N, which turns the gear indicator into a binary temp gauge. If it's flashing or something, you're good. Or if it's solid... I can't remember. Check the Lexus forums for this, but I would avoid using a temp gun.

 

[BrainThicknessVariation]

A scangauge is also a good tool. I want one but they expensive so if I feel the need i can use our Bluetooth scanner and my phone as a scangauge, or if I have to do vehicle specific stuff i can always drive around with the wired Autel and have someone else read me the numbers

Depending on your computer skills and level of patience, I can confirm that this knock-off Techstream works for some models. In my case, a 2018.

This provides full Techstream capabilities, which is quite expensive otherwise if you go through Toyota/Lexus.

The only caveat is, you might need to download an older version of Windows to use it. The good news is, those versions are actually free.

 

[JeffKeryk]

You underestimate how useful an IR thermometer is. You can find stuck thermostat, bad wheel bearings, how cold your a/c is, what temperature your lawnmower runs at, etc. Also most have a laser pointer built in so you can use it as a pointer if you want.

Also they're like $10

A scangauge is also a good tool. I want one but they expensive so if I feel the need i can use our Bluetooth scanner and my phone as a scangauge, or if I have to do vehicle specific stuff i can always drive around with the wired Autel and have someone else read me the numbers

I use a cheapo IR gun; I just check different spots on the pan. I do the fluid check at the low end of the range, figuring the fluid could be a couple of degrees hotter.

If this is inaccurate, well I don't care. Good enough, as far as I'm concerned.

 

[paulo57509]

With my Toyota, once you enter the temperature detection mode and you note the shift quadrant, this is how to interpret the fluid temperature:

What's odd is that, regardless of whether you use TechStream or not, you do the N-D toggle to enter temperature detection and monitor the shift quadrant when you enter temperature detection mode.

I think the FSM is incorrect with the TechStream procedure; why would you need to use TechStream when the next step is to do the N-D boogie to enter temperature detection mode?

IR gun? Yesh, much easier.

 

[BrainThicknessVariation]

I think the FSM is incorrect with the TechStream procedure; why would you need to use TechStream when the next step is to do the N-D boogie to enter temperature detection mode?

What do you mean?

 

[paulo57509]

What do you mean?

Keep in mind the above procedures are from the FSM for a 2021 Highlander with the UA80E transaxle. Before my initial post I had to map both processes.

Comparing both procedures with/without GTS (GlobalTechStream), using GTS is redundant (Lines 23-25). It appears that you use GTS to determine what the fluid temperature is. Than you go thru the steps to use the shift quadrant to determine what the fluid temperature is....again (Lines 26-35).

The only reason I can see for using GTS is to possibly save you the time of going thru Lines 26-35, if you're so lucky that the fluid temp falls within the adjustment temperature.

Unless I'm missing something or the FSM isn't clear, it really doesn't matter if you use GTS or not. You end up in the same place by doing the N-D toggle.

 

[BrainThicknessVariation]

Unless I'm missing something or the FSM isn't clear, it really doesn't matter if you use GTS or not. You end up in the same place by doing the N-D toggle.

Ah I see what you're saying. You can probably just check the temp outright, but who knows. I didn't have Techstream when I did it. However, now that I do, it's come in handy. Eg, using the automated brake bleeding feature.

 

[KrisZ]

The first time I did the cooler line exchange on my minivan I used an IR gun as I didn’t have a monitoring software. I measured the aluminum case in few places and not the black oil pan.

Recently I performed another cooler line exchange and this time I could monitor the ATF temp. The final measurement on the dipstick came up the same as with the IR gun.