The coolant sensor went bad on my tractor and I have a qustion about the old and new one. The small one is the old one and that fits and screws in,the new sensor has more threads 9 to 4 and new screws in but stops at 4 threads. So my qustion is can a machine shop file the extra threads down?

yes they could but

you get thread engadment , put some Teflon tape on that an if it doesn't leak and if nothing will hit the part sticking in the block I would run it.

those look like a pipe thread you don't need to bottom them out just snug with some thread sealer.

X2

I think you have two different thread types the new one looks like pipe and the old one looks like oring/straight thread and I’d say you got the wrong one.

You could also put a jam nut on once it is tight.

This


Looks like A-N thread on top and pipe on bottom. Common plumbing threads on vehicles.

vs-npt-fittings-and-how-they-relate/

Try that again, lol.

https://www.onallcylinders.com/2013/06/06/quick-tech-an-vs-npt-fittings-and-how-they-relate/

Like above one looks like NPT and the other is different. They are hard to find but they do make bushings that go from one thread to the other

Before that I'd go back and make sure you have the correct temp sensor.

That Pete I'll try that.

I usually try to find a mechanical gauge that has long enough cable and mount the gauge upon the hood, or dash that is close enough for me to see it.

I may have missed the thread difference in the two , take a closer look at that

the new one looks pipe thread the other one I can't see as well from that angle , set them next to each other in the same direction , pipe tap has a slight taper to it

if they both look the same then , yes thread seal and go

If it is the same thread the two should mesh 100%. I am pretty sure they are not the same.

I screwed the long one in and I can't turn it anymore. You will see with this pic I can't get a socket on it because the housing for the bolt that goes into to excust manifold is in the way so I the only thing I have is a vice grip. I also put Teflon tape on the threads.

if by meshing I assume you mean the threads will match if laid next to each other.
Unfortunately all you are checking is thread pitch or the number of threads per inch.
Pipe thread (NPT) is tapered while there is a straight pipe thread (NPS) which is not tapered.


I suspect the old one might be NPS and the new one looks to be NPT.

,

if you can't screw the new one in any more is it cause the sensor hits something inside the engine or cause the threads get tight?
check to be sure that the sensor isn't hitting something in the engine.
If not and its the threads thats the way NPT threads work, they will thread in and get tighter as you screw them in.
Have you never put pipe fittings together and experienced this?

Well I have sucess!! No leaks when tractor was running I used the blue Teflon tape on this. Thank for all your reply.

LOSE THE VICE GRIPS, and use an open end wrench, before you REALLY screw up!