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Discussion Starter · #1 ·
Alright I got the gauge and everything yesterday but can't find out where to put the sensor for the tranny temp. Any suggestions. Preferably not the T splice unless I can make one from home depot I'm stationed overseas and parts take forever to get here. Thanks guys
 

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The only other choices I can think of would be to either screw the sensor into the test port on the transmission. I believe the port is 1/16 so you will probably need a reducer. Only problem with that is that I have heard it is not the most accurate spot.

Your other choices are to get an aftermarket transmission pan with a spot for the sensor or you could get a weld-in bung and weld it into the stock transmission pan.
 

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Do NOT put your temp sensor in one of the threaded pipe plugs on the passenger side of the bellhousing. These are dead-end circuits (test ports), so you will have no flow past your sensor. You will NOT get an accurate temp reading.

There are two important trans temps to measure: sump temp and "to cooler" temp. The "to cooler" temp (also known as "converter out" temp) will be the hottest oil in your system. To read this temp, install your sensor in a "tee" fitting that you splice into the "to cooler" trans cooler line (this is the UPPER line coming out of the trans). It is usually easiest to splice a sensor into the rubber hose portion of the line (up near the radiator). Make sure the actual sensing element is up in the middle of the flow stream.

The "to cooler" temp will fluctuate pretty rapidly. When the torque converter clutch (TCC) is unlocked, this will show true "converter out" temp, which will climb rapidly during high torque, low speed maneuvers (like launches from a stop, climbing a steep grade, etc.). Try to keep this temp below 300°F. When the TCC engages, the "to cooler" line is fed with oil from the trans sump, so it should read something close to the sump temp. Therefore, you will see this temp reading going up and down as the TCC unlocks and re-engages.

There is already a sensor in your transmission that reads sump temperature. If you have a scan tool that will read data using PIDs, you can program it to read this thermistor. The PID was A01B on older trucks, and it is B011 on newer trucks (2007 and later, I am sure, but I don't know how much earlier this code was used). This should return a signed 2-byte value with a scale factor of 0.015625. So you read a 2-byte value (like 11968) and multiply it by 0.015625 to get the measured sump temp in °F (in this example, 187°F).

Or you can buy an aftermarket oil pan (with a temp sensor port), or get a port welded into your existing pan, and install your sensor there. But if you gotta spend some more $$$ (for a new or modified oil pan), I think I would use the $$$ to but a programmable scan tool, use that to read my sump temp, and install the sensor into the cooler line. That way I could read BOTH temps.

I would generally suggest keeping your sump temp below 220°F for long trans life, and you usually want it in the 160-190°F range. Short spikes to 220°F (or higher) are OK as long as you don't run up there for long periods.
 

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Discussion Starter · #4 ·
wow, great info bud. im going to do the T up in the rubber hose. so whats my temps i should be running for that location? im bout to put in my 2800 circle D converter is this gonna run my tranny hot?
 

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wow, great info bud. im going to do the T up in the rubber hose. so whats my temps i should be running for that location? im bout to put in my 2800 circle D converter is this gonna run my tranny hot?
The "to cooler" line temp should be about equal to the sump temp when the torque converter clutch (TCC) is engaged. Normal sump temp is 160-190°F. In heavy operation it can get higher than that; I would try to keep it below 230°F if I were you. When the TCC is unlocked, your "to cooler" temp will be the actual converter-out oil temp, which will normally be higher than sump temp. It can go up really quickly in high-power situations (like during launches from a stop, towing a trailer up a grade, etc.). Keep this temp below 300°F if possible. Yes, I would assume you will see higher temps from your aftermarket converter than from the stock one. The 300°F limit still applies.
 
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