OK, so i was installing my egt into my manifold yesterday and bought a 1/8 npt tap from auto zone. I think that was the problem. Now I got a hole in my manifold and no threads. Is there anything I can do to fix it. Maybe take it to a muffler shop and get them to weld in the egt?? Any help would be greatly appreciated.

 

Why no threads? Did something break?

 

You can get a threaded bung or bushing in a larger diameter. Then just screw the thermocoupler into it. Just make sure you will have the proper depth for the thermocoupler and you'll be good to go.

I know Autometer makes them. You can find them here:

http://www.autometer.com/cat_accessories.aspx?sid=47

Good luck,

Austin

 

Sound like you used the wrong size bit. Maybe a heli-coil can fix it?

 

The tap that i bought from autozone seemed to break threads on the tap itself when i was using it. Hopefully that makes sence. I could get about a half turn with the tap and it would get real tight like it was cutting some threads and then it would come lose when turned some more. The tap was supposily made of tungsen.

 

thanks guys for the posts, thought i was up **** creek. Hopefully i'll have her up and running today!

 

Actually i think the drill size i used for an 1/8" npt was 11/64". Hope this helps!

 

okay I think what you're doing is actually stopping as you tap. It does have to cut the metal and that takes some pressure. It's not like just screwing in a bolt or screw into a threaded hole, you're making the threads so it's some work. You need to make sure you keep pressure on the tap as you turn it. You also need to make sure you keep putting oil on it to lubricate. The hardest part is getting that initial "bite" on the tap to get it going in.

 

The official size would be a "R" bit but good luck finding one of those. The closest you'll find in you average store would be a 21/64th.

 

5/16 is what the instructions said it should be a 21/64? guess i'll get some of those heli-coils and pray that works, but first try a "R' bit or a 21/64 bit (that is if i can find one) and a new 1/8 NPT tap but if that fails then the heli-coil. the tap i am currently using looks like a few of the first threads are missing i mean parts of the threads are broken off, i know this isn't good, so i'll get a new one.

 

Luckily a 5/16 (20/64) is smaller than a 21/64 bit. You're right, the threads on the tap should not be broken. I used a 21/64 bit and 1/8NPT tap from the hardware store. I don't trust many tools from an automotive supply store, unless it's a reputable brand of course. Trucks and parts houses are usually ok..

 

When you tap the threads, you have to add oil to help them cut, plus you have to reverse out to clear the just cut threads, and then do another 1/4 turn or so, back it out a little, etc... I thought I would never get the tap to start cutting the threads and it just kept popped out. Eventually it does start and cut the threads... Then you have to figure when to STOP. To me that was the hardest part, did I cut enough threads to hold. You got to have at least 4 (or more) turns of the thermocouple adapter. If you go too far (tapping the threads), then the adapter bottoms out and you do not have a seal.

Dave

 

Sounds like you may not have had enough pushing power on it at this point. When you feel it start to bite, you have to keep good steady pressure on it for about another half turn, then back out to clean theads. Rethread until it gets tight and apply more inward pressure until it starts to cut again. Back up after every 1/2 to 3/4 turn to clean tap. Taps do look worn or even broken on the start ends. They don't do all the cutting with the first pass. It's not the easiest thing to do because of the posisiton and angle of the hole you are working on.
Good luck and take your time.

 

Don't forget to suck out the metal shavings from drilling and tapping before you put your thermocoupler in

 

Or just have the engine running.. A lot of air will be coming out of that hole. I also put some red grease on the tap to catch any shavings.