metric pipe plugs

[89Mirageman]

I was removing the socket head plugs on my 1.6 Hyundai head and a few stripped and had to be drilled out. Unfortunately this messed the threads up a little so my plan is to go to the next largest size. I can't really use a npt pipe plug because the next size up is 1/4 which is almost twice as big as what came out. I found these on ebay and I guess they are correct. I'm assuming whatever I put back needs to be tapered. Hard to tell if these are or not. Any ideas?

click

 

[iceman69510]

Not necessarily tapered. NPT is tapered, thus the name, National Pipe, tapered. BSP which is typically used by the Japanese, is parallel thread. Doing some checking this afternoon, I see some comments about metric pipe thread (DIN actually) is possibly slightly tapered, but not as much as NPT.

Basically what you use for plugs is going to require a properly sized tap to complete the job.

 

[89Mirageman]

I'm thinking the plugs that came out are 1/8" BSPT, I measured them and there is a very, very slight taper to them. Do you think it would matter if I went back with a parallel thread? I would think as long as they had some sort of pipe sealant on them I'll be fine.

 

[iceman69510]

I was not 100% accurate before. There is BSPP (parallel) and BSPT (tapered) and the Japanese typically use BSPT as you mentioned. I agree a parallel or straight thread would be fine for this purpose with sealant with it.

 

[89Mirageman]

Awesome, so I can just pick up some sae socket heads locally then. No need to order any special metric stuff since it doesn't need to be a special tapered plug. Thanks!

 

[thruarod]

I'm wondering what would stop a straight plug from screwing right on through the hole, into the oil galley. If I were to go with straight threads, I would want to use something like this to block up the hole, just as Mitsubishi did on the 2G head. Similar concept to the fittings on the 90 OFH lines that go to an oil cooler.

 

[89Mirageman]

Thought about that too. My plan was to practice on some thick scrap aluminum with the tap and only tap it til the set screw screwed in and was flush, or maybe stuck out just a little. Then put some tape or something on the tap so that I could replicate it and know how far to tap each hole.

I haven't really looked into it but didn't know if something like you posted up would interfere on the timing belt side since the oem ones were pretty much flush. I doubt they would but not sure.

 

[89Mirageman]

I also figure a low head or button head with an o-ring on it would work well too. With thread sealant too for extra insurance.

 

[thruarod]

Check out McMaster's pressure sealing washer. Might be better than an O-ring, and reusable unlike copper crush washers.

 

[89Mirageman]

I ended up just ordering the brass plugs in the link from my first post in 12mm 1.25. That's a little larger than the ones that came out but still way smaller than 1/4" NPT. I sent the company a question and they said they were tapered just a bit so hopefully they are. We'll see. Now the 2-3 week wait from China /ubbthreads/images/graemlins/grin.gif.

 

[jeverts]

Quoting iceman69510:
Not necessarily tapered. NPT is tapered, thus the name, National Pipe, tapered. BSP which is typically used by the Japanese, is parallel thread. Doing some checking this afternoon, I see some comments about metric pipe thread (DIN actually) is possibly slightly tapered, but not as much as NPT.

Basically what you use for plugs is going to require a properly sized tap to complete the job.



NPT Stands for National Pipe Thread. NPSC (Straight Coupler) and NPSM (Straight Mechanical) are your straight pipe thread call outs (there are more but they are relatively not used in cars. There is also a fine call out on these denoted with an F.

Just clearing that up /ubbthreads/images/graemlins/wink.gif