Auto Transmission temperature gauge

[testarossa]

I have heard that there is a temperature gauge available for the Toyota automatic transmission. Does anyone know where I can buy one? Also if anyone has one, is it a useful thing to have?

Thanks for any info.

[Gulfstream Greg]

There is not a specific one just for the Toyota. But any transmission or oil temp gauge can work. It just needs to be able to read 300 degrees plus. JCWhitney has an analog and a digital one. I would suggest the digital as it is easier to read if you have vision age. And yes they are great to have. Right now you are guessing on the temp assuming its high during one point or cool. The reality is it will be running hot when you think it would be cool. Having the gauge will allow you to discover driving methods that will help keep the temp down and from reaching critical temps.

The sensor would best be placed in the oil pan but that requires welding in a fitting for it. So most opt for using a TEE and placing it in the cooler line that runs from the transmission to the radiator. One thing to watch for is to make sure that when the tee and sensor are assembled that they do not restrict the oil flow. In other words the sensor should not protrude down into the flow line. I drilled out the fittings so that there was max flow and that also allowed oil to flow around the sensor. I have seen a couple of installs where the sensor poked way down into the flow channel basically cutting off the oil flow. Use of adapters to raise the sensor out of the channel is required. Also since most gauges and sensors are electric you must fabricate and attach a ground wire to the tee assembly to get it to work.

[86rader]

wouldn't it be possible to drill a hole in the pan and mount it using plastic washers? Why is welding neccessary?

[Gulfstream Greg]

I suppose you could use plastic washers but they should be able to withstand oil and temps of 300 degrees plus. The thermal range of outside air temp to 300 plus temp will cause some expanding and contraction and the washers may leak after awhile or worse, work the inside nut loose. And you never want the possibility of it coming loose and draining your oil. Welding or braising a fitting into the pan allows you to screw the sensor directly in and it and will never leak and never come loose. What ever way it is mounted in the pan make sure where you place it that there is enough room inside so that the sensor does not interfere with or touch any internal parts. Any how one day I am going to pull the pan and braze a fitting into it. There is one huge draw back though so maybe mounting with washers would be better and that is the sensor. If it fails and you have to go to a different manufacturer will the new one fit the mount. I suppose you could put in a large mount and use adapters to re-size it down to fit the sensor. It is important to note here that usually you want the sides of the sensor to be exposed to the oil. It may be necessary to drill out any adapters in order to give some side clearance. Even with the tee in the line method I drilled out the barb fittings so that they were closer to the oil line inside diameter so as to not restrict the oil flow to much.

[testarossa]

Has anyone given thought to using the transmission dipstick hole for inserting a temperature sensor, therefore eliminating the complexity of messing with the oil pan ???

[Gulfstream Greg]

That's an interesting concept. I seem to remember some saying that there is an after market dip stick with a sensor built into the end.

Here is a good article on installing it in the pan http://neptune.spacebears.com/cars/stories/trgauge.html