Engine Drain Cock

netpacket79 · Nov 23, 2014

Wondering if anyone can confirm, is the engine side threads on these drain cock NPT 1/4"?
thx, Bill

netpacket79 · Nov 23, 2014

This is on 48' 8N gas by the way.

Bruce (VA) · Nov 23, 2014

I can confirm it's p/n 8115 & that it's 1/4". And the same p/n applies to the radiator drain cock as well. But, the MPC does not specify NPT.

But I'll bet you a beer it is.
75 Tips

old · Nov 23, 2014

Just a common radiator type drain cock that some one installed into the block drain plug hole

Ken(Ark) · Nov 23, 2014

Yes , a 1/4" NPT draincock or pipe fitting / plug will screw into that hole .

Did you know pipe threads are tapered . If you clean up old threads with a tap it will set the fitting in deeper . If they were not tapered a plug would spin all of the way through and would never tighten up .

ScoutB · Nov 23, 2014

(quoted from post at 23:44:50 11/23/14) Yes , a 1/4" NPT draincock or pipe fitting / plug will screw into that hole .

Did you know pipe threads are tapered . If you clean up old threads with a tap it will set the fitting in deeper . If they were not tapered a plug would spin all of the way through and would never tighten up .

Tapered 1:16 to be exact, or 3/4" per foot. Just in case it ever comes up on "Jeopardy".

greywolf224 · Nov 24, 2014

Yep a 1/4". Picked up a few shiny brass ones at my local ACE Hardware store.

netpacket79 · Nov 25, 2014

Thank you guys - got one from Napa and works like champ.

TheOldHokie · Nov 25, 2014

(quoted from post at 23:44:50 11/23/14) Yes , a 1/4" NPT draincock or pipe fitting / plug will screw into that hole .

Did you know pipe threads are tapered . If you clean up old threads with a tap it will set the fitting in deeper . If they were not tapered a plug would spin all of the way through and would never tighten up .

In this case yes but not all pipe threads are tapered. :shock:

The pipe threads on a female swivel are a common example of straight pipe threads (NPSI) . They match external NPT pitch and diameter but do not interfere with the tapered threads on a male fitting. The length of thread engagement is shorter than on NPT female fittings and in the case of a swivel the seal is not made on the threads - it is made between the chamfered end of the male fitting and the seat in the bottom of the swivel.

Just in case it ever comes up on Jeopardy ;-)

TOH

Engine Drain Cock

netpacket79

New User

netpacket79

New User

Bruce (VA)

Well-known Member

old

Well-known Member

Ken(Ark)

Well-known Member

ScoutB

Member

greywolf224

Member

netpacket79

New User

TheOldHokie

Well-known Member

Similar threads