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Determining threads on coolant plug for tapping
Posted: Sat Jul 17, 2021 3:41 pm
by 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
Re: Determining threads on coolant plug for tapping
Posted: Sat Jul 17, 2021 3:59 pm
by bofahs
Pretty sure it's 1/4" NPT.
Re: Determining threads on coolant plug for tapping
Posted: Sat Jul 17, 2021 4:12 pm
by tst
3/8" NPT
Re: Determining threads on coolant plug for tapping
Posted: Sat Jul 17, 2021 5:19 pm
by 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
Re: Determining threads on coolant plug for tapping
Posted: Sat Jul 17, 2021 5:21 pm
by Command52
I see it has the word taper in it
Re: Determining threads on coolant plug for tapping
Posted: Sat Jul 17, 2021 6:12 pm
by 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
Re: Determining threads on coolant plug for tapping
Posted: Sat Jul 17, 2021 6:21 pm
by tmays
Command52 wrote: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
Re: Determining threads on coolant plug for tapping
Posted: Sun Jul 18, 2021 2:03 pm
by 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
Re: Determining threads on coolant plug for tapping
Posted: Sun Jul 18, 2021 4:59 pm
by 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
Re: Determining threads on coolant plug for tapping
Posted: Mon Jul 19, 2021 2:10 am
by Nelson 634
NJ Farmer wrote: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.
Re: Determining threads on coolant plug for tapping
Posted: Mon Jul 19, 2021 7:00 am
by 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.
Re: Determining threads on coolant plug for tapping
Posted: Mon Jul 19, 2021 7:20 am
by Command52
Again thank you guys very much I would be lost without you