??'s about EGT TC install

[TFlory]

I asked this in another forum and was directed here, so I apologize for the duplicate posts...



I need to know if this is right- I bought a 1/8 NPT-27 tap and 21/64 bit. (. 32). Is that right, or do I have to buy the 'Q' bit.

It does say on the tap that 21/64 bit is correct.

Also, any pics of TC install locations?

TIM

 

[robmints]

You don't need a Q. You usually want the tap to screw in about 2/3 the way in.



Photos here: https://www.turbodieselregister.com...pyro-thermocouple-installation-325-610-a.html



I find the drill size necessary usually ends up slightly larger than what is on most charts. I crossed out all my charts at work and wrote a T drill in with a Sharpie. We do mostly stainless and if you don't get the hole big enough the tap doesn't like it.

 

[Buffalo]

I can't answer your questions but, when I did mine, someone told me not to tap all the way into the manifold. Especially if the thermocouple is long. If you do, the end of the TC will back up against the inside,back of the manifold.



I sure was appreciative of that information because, I woould have gone all the way through & possibly had a problem.



The inside of the manifold, just above where the turbo connects, has metalwork in the center. It seperates the front 3 cylinders from the rear 3. My understanding is that the rear 3 cylinders are hotter than the front ones. Therefore, installation of the TC into the rear-most journal is preferable.



I'm not an expert in this stuff. The only one I've ever done was this one.



Joe F. (Buffalo)

 

[TFlory]

I installed the pyro Sat night. I used the 1/4 NPT w 7/16 bit. However, while drilling w the smaller bit first , I actually slipped and busted off the bit in the manifold! HS! I continued drilling w larger bits and when I stuck a mechanics magnet in I was able to retrieve the busted bit, and I was surprised by the quantity of shavings. Anyway, after that jackass move, the rest of the install went well.

/webdata/photopost/data/500/medium/Drill_bit_002.jpg#ad

 

[DeezelDood]

My sincere sympathies on your problem, but I'm glad it worked out. I think I'm the one that directed you here for robmints pictures. Very easy to snap off the pilot hole bit, as you have found. I have long arms and was able to set a good stance and hold the drill steady from the side. This job is tougher if you're balancing yourself on top of the engine. Looks like the the top of the manifold was a good idea (you'd be removing the turbo right now). Good points made above on the tapping. Most of the posts on this subject don't go into much detail on that. The manifold is thinner than the design depth of the tap, and NPT is tapered. Best bet is to go in half way, try to thread in the plug, then tap a a little at time time until the plug goes in snug. It's also a good idea when tapping to back off the tap every half turn or so to clear the shavings from the teeth.