Quick Question about coolant temperature senders/ sensors

[DanMcG]

My sender is bad and needs replacing, I need to order one but don't want to pull the old one until I have the new one in hand (and it stops raining) but I see they have two sizes, 1/2"-14 and 3/8"-18. Is there any way to tell which one it could be? the motor is a 86 warranty 350 block in my 85 k10. And a 13/16 socket fits on it.
I'm guessing it's the larger 1/2" size but I'd probably be wrong.

Thanks

 

[F-64]

I only see the 3/8 offered for an 86 350.
Buy both from your local store and return the one you don't need.

 

[chengny]

My sender is bad and needs replacing, I need to order one but don't want to pull the old one until I have the new one in hand (and it stops raining) but I see they have two sizes, 1/2"-14 and 3/8"-18. Is there any way to tell which one it could be? the motor is a 86 warranty 350 block in my 85 k10. And a 13/16 socket fits on it.
I'm guessing it's the larger 1/2" size but I'd probably be wrong.

Thanks

As info; 1/2 NPT is very close to 11/16" in diameter and 3/8 NPT is just about 9/16" diameter. You should be able to use an open end wrench of each of those sizes to gauge the body of the sensor - and make a good educated guess.

 

[75gmck25]

Based on my experience, the 1/2” thread is much more common. I had the smaller sending unit in an a old late 70’s block, and in some new aluminum heads, but all the newer heads used the larger sending unit.

Also check carefully to ensure the new sending unit has the right resistance for your gauge. It took me quite a while to find the right one for my ‘75. All the ones for newer trucks made the gauge read much too low. The correct one puts my gauge at just above the 1/4 mark at about 180-185 degrees.

Bruce

 

[DanMcG]

Also check carefully to ensure the new sending unit has the right resistance for your gauge.
Bruce

How does one find that information? I haven't seen it offered on any of the sensors I've looked at.

 

[DanMcG]

Looks like the rains will be letting up today so I'll just pull the old one now. Thank you all for the advice

 

[75gmck25]

Finding the resistance information is a real easter egg hunt and I've lost track of all the references I tracked down.

It looks like the right one for your truck is 3/8" NPT, and its an Standard Motor Products TS76, which should cross-reference to a GM 8993164.

Bruce

 

[DanMcG]

Thanks Bruce, I just got done pulling it and it was a 3/8 (.657) and now have the TS76 on order from Rock Auto.