Thread Pitch for CTS

Rich · **Posted:** Thu Dec 15, 2011 1:13 am

I am working on converting my mechanical fan to a two-speed electric fan, and the last bit of issue is getting the thermo switch I am going to use plumbed in with the factory coolant temp sensor on the thermostat housing.

Does anyone know the thread pitch of the OEM CTS? It almost looks M12x1.5 but I want to make sure before I start ordering plumbing bits... without yanking mine out.

Hoosier CRD · **Posted:** Thu Dec 15, 2011 7:13 am

Rich,

I do not know the thread pitch on the Coolant Temperature Sensor (CTS). However, I do have some suggestions as to how one could find out:

Find the part number, call to a local dealer and see if they have one on the shelf. If they don't, they can tell you which dealer does, maybe it will be one in your area.

Secondly, go to a local parts house and have them look it up for you. Repeat Step One as necessary

Third, look up the part online on a Mopar parts site. Typically they are also dealerships. Call and see if they will measure it for you.

Fourth, which you have also mentioned, extract the CTS you have and give it a measure.

Lastly, you may also check on the plumbing parts where the I.D. of threaded holes are close to, if not exactly the same as, the O.D. of the CTS. Looking into the metric threads available for the plumbing bits you seek, you will likely see one, possibly two thread sizes. Keep in mind that you may have to use inserts/bushings in order to get the I.D. size you need. Hope this helps.

FWIW,

Hoosier CRD

Rich · **Posted:** Thu Dec 15, 2011 1:11 pm

I converted to dual electrics on my XJ and gained 3mpg across the board by getting rid of that mechanical fan, granted my clutch was failed in the "closed" position so I was churning it 100% of the time. This is the switch setup I used on that, and it has worked flawlessly.

The OEM CTS on my XJ is a 3/8NPT, so I took a F/F/F 3/8NPT, and attached it to the thermostat housing with a M/M connector. The OEM CTS threads into the fitting inline with its original hole. The switch I am running for the fan is a M14x1.5, similar to the 2spd switch I am going to run for the KJ's 2spd fan. To adapt that switch, I took a 1/4FPT to 3/8MPT bung, built a jig, and ran a 1/2" drill bit through the center just knocking off the inner threads. I then ran my trusty M14x1.5 tap through to create the adapter.

From the looks of the thermostat housing, there is enough material to drill the factory hole to M14x1.5, then get a M/F/F street-t, create an adapter similar to the above from M14 to M12 (or what ever the OEM CTS is) and put it all together.

I pulled my mechanical fan out for the winter, and while in there this morning, I noticed on the bottom passenger side of the radiator end-tank there is a bung that stick out, facing the rear of the vehicle. Does anyone know what this is, and if it is a plugged fitting?

papaindigo · **Posted:** Thu Dec 15, 2011 2:37 pm

On the KJ there is a fitting on the bottom rear passenger side of the radiator tank that is the lower radiator drain plug. Don't know if that's what you are seeing on your XJ

Rich · **Posted:** Sat Dec 17, 2011 2:33 pm

papaindigo wrote:

On the KJ there is a fitting on the bottom rear passenger side of the radiator tank that is the lower radiator drain plug. Don't know if that's what you are seeing on your XJ

That must be the one I was seeing down there... anyone know that thread pitch? May be able to just use a fan trigger as my new drain plug

papaindigo · **Posted:** Sat Dec 17, 2011 5:34 pm

Not a clue. On the KJ it's just a plastic turn valve with a pretty steep pitch (e.g. not like a threaded bolt or pipe fitting)

Thread Pitch for CTS

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