Both are 1/8 NPT (National Pipe Thread)

You are better off drilling and tapping a hole in the thermostat housing for an additional temp sensor. There is already a 'boss' in the front that can be drilled and tapped for 1/8 NPT.

 

The thermostat housing for a 4.0 engine will fit 258 (4.2) and it has pre drilled and tapped hole for temp guage sending unit. Discovered this when I ordered a crate rebuilt 258 and head didn't place to install sending unit. Don't kow about any other plumbing as my 74 dosn't have any.

 

Ok,

Here are the pictures of my engine. The above pictures i got as an example from the web.
Can i use these existing holes?

 

Top pic yes, bottom pic no.

Bottom pic is a knock sensor that is NOT a through hole into the manifold cooling jacket.

 

Well then I will using the top picture for the tempsensor. Is this also npt thread??? And if its not to much, anyone knows the threadsize?
Thanks!!!
Good advise:+1:

 

Yes it is. The sensor holes in the intake manifold are 1/4" NPT.

 

Ok ordered an 1/4 to 1/8 adapter.
What will be the best place? Install the original tempsensor in the manifold 1/4 and the new one (with degrees) on the old spot? Or the new water tempsensor in the manifold

 

Ordered an adapter? You can go to any Home Depot, Lowes, etc and get one in the plumbing dept. Your gauge probably comes with one too.


If it were mine I wouldn't mess with the stock sensor and install the new one in the manifold.

 

Ok, question about this coolant temperature sensor on pic 1. Was that standard on the 1986 AMC 258?
Cant find any info on this sensor with this engine? Also the knocksensor is not standard on this year?
I only found this coolant sensor on a jeep J10 with 258 AMC

And your sure about the 1/4 ntp thread size?

 

Both sensors were standard in any 82 and up CJ. Look here: http://home.sprynet.com/~dale02/

100% positive it's 1/4 NPT.

 

The coolant sensor screwed in the intake manifold coolant passage relayed information to the MCU (Motor Control Unit) which adjusted the carb Stepper Motor for optimum fuel/air ratio. Other items came into play as well.

The Knock Sensor also played a part in keeping the advance timing at an optimum setting under load. It was standard on CJ's from 1982-1990 YJ's

It looks to be 1/4" NPT to me.

 

Thanks guys

 

Reason i got confused is because the shop sold me an 1/4" to 1/8" adapter (NPT) female 1/4" > 1/8"

http://www.racerallyparts.nl/webshop/technische-producten-voor-de-auto/koppelingen-en-olie-benzine-slangen/koppelingen/adapters/recht-verloop-npt-npt/adapter-male-female-1-4-1-8-npt

This adapter would fit my 1/8" temp sensor but is to small to fit the manifold
We work in metric....so therefore my question if you where sure about the 1/4"

 

Sorry but these NPT size are complete new to me, is it the same as inches? Found a lot of info on http://mdmetric.com/tech/cvtcht.htm
Can i use this conversion table?

Maybe its 3/8 or 1/2? I will measure the thread diameter of the engine coolant switch sensor later today in mm

 

Sorry but these NPT size are complete new to me, is it the same as inches? Found a lot of info on http://mdmetric.com/tech/cvtcht.htm
Can i use this conversion table?

Maybe its 3/8 or 1/2? I will measure the thread diameter of the engine coolant switch sensor later today in mm

https://en.m.wikipedia.org/wiki/National_pipe_thread

Npt threads are tapered fittings and are in the pipe's internal diameter sizes. You have a straight external 1/4" fitting with a 1/4" external measurement, totally different animal.

 

Diameter of the sensor thread of the coolant switch is 17.1 mm or 0,67 inch

http://www.engineersedge.com/hardware/taper-pipe-threads.htm

Will go on monday to a shop to get an adapter.

If someone has a link where to get one online with a link and the diameters it would my search less complicated

 

Diameter of the sensor thread of the coolant switch is 16mm or 0,63 inch

Will go on monday to a shop to get an adapter.

If someone has a link where to get one online with a link and the diameters it would my search less complicated

Normal threads won't work for a NPT fitting. You buy them by the iron pipe size. A 1/4" iron pipe has threads about 9/16" or your .6". They sell iron pipe by the size of the hole in it, not the size of the pipe or threads.
These threads are tapered to seal, they don't bottom out to seal.
You must have iron pipe where you live? It is used for gas lines and hot water cooling systems like boilers and radiators.
This might help.
http://www.nero.co.uk/Catalogue/150LB-NPT-Threaded-Fittings/Reducing-Bush

 

The sizes in NPT are also nominal, not exact.


How about some pictures of what isn't working. I'm not following at all what pieces don't work with other pieces. You already have the 1/8" NPT to 1/4" NPT adapter fitting as pictured. That adapter should thread directly into the intake manifold where you proposed removing the existing sensor.

 

Thank you.....