Using a IR temp meter to measure trans temp?

[Raven]

Hi,

I may as well make the question short and simple.

A number of transmissions these days which are not equipped with dipsticks have special check or fill ports which are only accurate at specific temperature ranges. Is it considered acceptable to use an infrared thermometer on the transmission pan itself to determine if the fluid temperature is in the correct range for checking?

Thanks fellas.

 

[RooflessVW]

It's not as accurate as using measured values, but is pretty close if your trans pan is black.

Mine reads about 5°C lower than the measured value.

 

[901Memphis]

Closer than guessing but I think the scan tool is the most accurate

 

[Chris142]

I did this last week.

 

[Raven]

Our "Slightly Advanced" OBD II scan tool can't fetch transmission temperature. Also some like the '11 Tundra require some funny procedure to put it into transmission check mode etc.

Any other voices?

 

[Johnny2Bad]

If it's your only option it's obviously worthwhile, but it's not a perfect means of measuring temperature. I believe it's actually measuring Infrared Emissions, so you would get different readings in sunlight and shade, for example. Your best option in cases like that is to measure often and record, maybe even graph, your readings. The trend line is just as useful as a direct measurement sometimes.

It might also help if you use a sort of control to compare with. Say, a water jug with a measured amount of water that you can measure with a direct temp reading device ... a mercury thermometer would be fine, as would a $10 Cook's Digital tool. Measure your Control with the IR Meter, compare to your thermometer, and that way get an idea how accurate or by what correction factor is needed. Then you would be able to have high confidence in your IR measurement from outside at the pan.

 

[Trav]

A cheap DMM with temp probe is useful if the unit has a dipstick, the probe is long enough to get down into the fluid and at least give you pan fluid temp.
You can also check the line temp at the cooler by placing the bulb on the line and holding it there for a min or so. This is just an example of what I am talking about you can find them for cheap anywhere.

http://www.ebay.com/itm/Velleman-DVM890L...p-/122308292602

 

[zzyzzx]

My scan tool give live data, and that is what I would use for any OBDII vehicle.

 

[Trav]

What if you don't have a scan tool that can read transmission temperature? The scant tool possibly isn't the most accurate measurement, many transmissions measure only pan fluid temp.
The hottest fluid is coming out of the pump going to the cooler, that's an important measurement also as it tells you the difference between pan temp and after its been through the unit and converter. Using the two readings you can determine how much heat is being generated in the box and if its too high it could be caused by excess slippage in the clutches or converter clutch.
It can also help determining the effectiveness of any cooler installed in the system.

 

[PolarisX]

Not every ECM will report trans temp or at least not in a friendly way.

My Impala does just fine, the Malibu gives us nothing, just a static value.

 

[Trav]

Yes that common when older design units are used in more modern vehicles, a direct reading is best with these.

 

[MobilinHyundia]

My Scangauge 2 can measure coolant, engine oil and transmission temp on my 2009 Sonata.
When I got it it was not possible but after a firmware update now it read all the vehicle fluid temps.
It is permanently mounted on the dashboard to see it.

 

[maxud]

I have used IR thermometer before.
Realistically, the procedure really calls for the transmission fluid to warm up to normal operating temperature, which can be achieved by
running the car in idle for some time, and shift the gears while the car is running, while holding the foot on the brake pedal.
If you got nothing else, just let it idle for 10-15mins and row through the gears couple of times, should be good to go.

 

[Trav]

You could be sitting there all day doing that, chances are it wont even get close to operating temp. About 10-20 miles depending on ambient air temp, unit fluid capacity.

 

[Cbst09]

I recently performed a fluid drain and fill on my Subaru CVT transmission. The service manual called for a specific fill procedure to get the the transmission fluid up to a specific operating temp. I think that the whole temperature thing is most practical for service centers that don't have the luxury of waiting for a car to get cold and the thermal expansion of transmission fluid makes it tricky on warm cars.

My easy method is that I do a cold drain and a cold fill. In other words I drained the CVT fluid out and then measured the exact volume of fluid that came out. I then filled approximately 75% of that amount back into the transmission, started the car up and cycled through the gears to distribute the fluid (this step is necessary to be able to fill back the final 25% of fluid) and with the car running I put back in the remainder of the fluid. In my case I removed 5 1/2 quarts and put in 5 1/2 quarts.