Does anyone know the thread size for the Coolant Temp. Sensor?

I'm thinking about rigging up a secondary sensor with a stock coolant temp. sensor, does anyone know what the thread size/pitch is? is it a pipe thread?

this is for an '88 4.0

I could swear it was like 3/8", or was it 1/2"? I can't remember now, but I know it was a NPT fitting, since the plug I got came from the plumbing shop an fit just fine.

hey thanks, if it's a standard NPT size then I can figure it out pretty easy

IMPORTANT NOTE - if you are going to get a reading that is anything like accurate from a temperature sensor in a fluid bath, there MUST be constant coolant flow over the sensor probe! Failure to ensure this will result in a "pocket" where you get delayed readings due to the lack of fresh fluid flow!

Just plumbing in a T won't work for this one. You might want to think about switching in an HO thermostat housing, this has a fitting for another CTS and will get coolant flow, plus be in a location to let you know if the thermostat should be open or not.

BTW - Why do you want to add another sensor? Just wondering...

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check, i'll make sure it gets good coolant flow.

i'm going to put one in my transmission pan, or cooler lines, or somewhere related to my tranny, I haven't decided exactly where yet. then i will run the engine and tranny sensors both to the gauge and have a switch to control which one is showing on the guage, then i can get temps off both without needing an extra gauge.

The best place for a tranny coolant sensor is the tranny pan, but that's also the most vulnerable location.

is the pan thick enough to tap? or would i need to get some Al plate welded to it first then tapped?

Interestingly enough, a T fitting does make a nice way to plumb a tranny temp sender somwhere safter than the side of the pan. Use a T large enough to take the lines on the "run" (the arms of the T) and the sensor goes into the "branch" (the base of the T) - and plumb it into the return line from your cooler. This will allow you to move the sensor somewhere more out of the way, but still give you an accurate reading.

My earlier advice wasn't meant to say a T wasn't a useful way to plumb in a temperature sender, merely that it was critical to make sure there was good, CONSTANT fluid flow over it. If it were merely a pressure sender, then flow wouldn't matter - just that it was plumbed in to always get full pressure (which is why you can use a T to pop in another pressure sensor at will - just make sure there are no restrictions between the pressure source and the pressure sensor...)

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