Waterpump hosebarb

**ginoz28** · 02-05-2013, 08:56 PM

I couldn't find any freeze plugs and then I was checking the barb against a 3/8 thread and the thread looked to small compared to the barb. So I just got some jb weld and put it back on and I'll see what happens. It says its good to 550 degrees.

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**chile** · 02-05-2013, 09:05 PM

There is a difference between regular nut/bolt 3/8 thread and NPT 3/8 thread.

**RamAir95TA** · 02-05-2013, 09:33 PM

Big mistake on the JB Weld. It will eventually fail. The cooling system is under 18psi of pressure.

NPT stands for National Pipe Taper. The threads are tapered for sealing pipe threads. They are not the same as standard nut/bolt threads and the two are not interchangeable.

**ginoz28** · 02-06-2013, 12:04 AM

Originally Posted by chile

There is a difference between regular nut/bolt 3/8 thread and NPT 3/8 thread.

I know that I needed a ntp tread tread but, when I put it next to the 3/8 plug the barb was bigger or the same size at the top of the taper on the threads so it would of been loose or the tap would.have just slipped straight in.

**RamAir95TA** · 02-06-2013, 12:42 AM

Clarify here. You said "when I put it next to the 3/8 plug", what are you talking about?

A 3/8" NPT pipe tap is .675" in diameter while a 3/8" standard tap is .375". You need the pipe tap (assuming the 3/8" pipe tap is the correct size).

When you talk about NPT pipe threads the designated thread pitch has absolutely NOTHING to do with the actual size of the pipe/fitting.

**ginoz28** · 02-06-2013, 12:58 PM

What I'm saying is it would have fit like this with the bottom of the thread not touching the walls and not sealing anything. And if you bottom out the tap,your just straightening the walls and it won't have the taper to be able to seal tight.

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**RamAir95TA** · 02-06-2013, 03:36 PM

For you to tap the hole for NPT threads you would have to measure the OD of the current hole, then determine what size the closest appropriate NPT threads would be (drilling and enlarging if need be).

**BIG CAT** · 02-06-2013, 04:45 PM

Originally Posted by ginoz28

What I'm saying is it would have fit like this with the bottom of the thread not touching the walls and not sealing anything. And if you bottom out the tap,your just straightening the walls and it won't have the taper to be able to seal tight.

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did you check the next size up tap?

**ginoz28** · 02-06-2013, 05:12 PM

Now I'll know what to do when I have it out of the car, I'll drill and tap the inlet and outlet for 1/2 plug.
Thanks for the info guy's

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