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Best location for Trans Temp sensor ??

11K views 10 replies 6 participants last post by  444-4D 
#1 ·
A friend of mine was telling me that the trans temp sensor should be reading the temp of the oil on the output side, so he has installed the sensor on the line coming out of the trans that leads to the cooler, so as to read the hottest temp the oil reaches. All of the aftermarket pans I see have a tapped port for sensor installation, but that wouldn't be reading the hotest oil, would it? Is the sensor installed in the pan ok? Where is a factory sensor installed when the truck comes with a temp gauge?
 
#2 ·
Most install it in the pressure test port on the drivers side of the trans case. The plug is just above the pan and towards te front of the trans. I don't think the info I'm getting from that test port is exactly correct so I'm going to move mine to the pan. I have a new pan laying here waiting on a bung but I can't find a bung like I want so I'm going to have to make one. If your pan has a place to install a sensor thats where I would put it. One interesting thing about the pan temps, Richter69 has said that there is a difference of about 15° from the front to the back of the pan.
 
#4 ·
[ QUOTE ]
A friend of mine was telling me that the trans temp sensor should be reading the temp of the oil on the output side, so he has installed the sensor on the line coming out of the trans that leads to the cooler, so as to read the hottest temp the oil reaches.

[/ QUOTE ]


Not a good idea.

Ford standard uses sump temp, or the temp of the ATF in the pan. When you take the sump temp, then Ford says the max sustained temp is 221º, and it's okay to let it creep above 221º for a short burst over the pass.

But Ford doesn't tell us the max temp of the ATF coming out of the torque converter. That temp will be much hotter than the sump temp - probably over 300º when you have a sump temp over 220º. But it doesn't matter as long as your tranny coolers work good enough to keep sump temp below 221º.

[ QUOTE ]
All of the aftermarket pans I see have a tapped port for sensor installation, but that wouldn't be reading the hotest oil, would it? Is the sensor installed in the pan ok?

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Yes. Then use about 220º as the warning line and about 225º or 230º as the red line.

For most of us that don't have the threaded bung in the tranny pan, we can get the same temp by installing the sender in the pressure port on the side of the tranny. The ATF from the pan is pumped past that port first thing after it leaves the pump, so it's still almost identical temp as the ATF in the pan.

[ QUOTE ]
Where is a factory sensor installed when the truck comes with a temp gauge?

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It's up inside the tranny way after that pressure port, so it usually reports temps about 10 to 15 degrees hotter than sump temp. If you use a scanner or something that grabs that temp from the PCM, then use about 230 as your warning line and 240 as your red line. My understanding is that the BD X-Monitor uses that temp, but I haven't confirmed that.
 
#5 ·
Thanks for the replies. I have already ordered an aftermarket pan with sensor point, so I should be good to go. I think I'm going to pull my trans and replace the mechanical diode. So, the new pan will go on during the repair.
Thanks again.
 
#6 ·
[ QUOTE ]
Thanks for the replies. I have already ordered an aftermarket pan with sensor point, so I should be good to go. I think I'm going to pull my trans and replace the mechanical diode. So, the new pan will go on during the repair.
Thanks again.

[/ QUOTE ]

Just don't change the diode only. It is way in the back, so you might as well do a complete rebuild with all the strong goodies you can.

Paul B
 
#8 ·
Thanks Casey_1. That was MY post from this morning /ubbthreads/images/graemlins/smile.gif. I had been searching all over for info on the diode, then Google pointed me right back here. So I posted the link for everyone. I had searched the forum again and again, with many different key words and couldn't find anything regarding a bulletin. I'm new to this forum and didn't realize the FAQ had the info.
Paul B, You're right, I should do a whole rebuild, rather than a patch job.
 
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