Determining threads on coolant plug for tapping

[Command52]

Trying to straighten the threads on my coolant drain plug, Am i correct that the thread is 3/8 16 and is this tapered pipe thread or just regular pipe thread Thanks Billy

[bofahs]

Pretty sure it's 1/4" NPT.

[tst]

3/8" NPT

[Command52]

Irwin Hanson High Carbon Steel SAE Pipe Taper Tap 3/8 in.-18NPT 1 pc
would this be the correct Tap Thank you Billy

[Command52]

I see it has the word taper in it

[Glen]

Hi,
Below is a listing at TM Tractor for a new cooling system drain plug, you can look at the info and pic.

http://www.tmtractor.com/new/st/3833fp.htm

[tmays]

Irwin Hanson High Carbon Steel SAE Pipe Taper Tap 3/8 in.-18NPT 1 pc
would this be the correct Tap Thank you Billy

Yes. Npt is national pipe thread, which has a taper

[SamsFarm]

There is a thing called a screw pitch gage / thread pitch gauge.

Comes in real handy at times like this!

https://www.starrett.com/category/11150 ... tBy=wp/asc

[NJ Farmer]

I would use a brass plug with either pipe dope on it or Teflon tape on the threads….remember you may want to remove that plug years from now or for next generation of Cub owner.

NJ Farmer

[Nelson 634]

I would use a brass plug with either pipe dope on it or Teflon tape on the threads…remember you may want to remove that plug years from now or for next generation of Cub owner.

NJ Farmer

Risk of galvanic corrosion. Not something I would do. I would use Copper or Aluminum anti-seize.
Just one persons opinion.

[Gary Dotson]

A brass plug (or fitting) will work very well with cast iron, I’ve used them for years, I’ve never seen any reaction between the two materials. I’d avoid using aluminum but about anything else will work.

[Command52]

Again thank you guys very much I would be lost without you