Drilling and tapping for an EGT probe - 5.9 CTD

[Cumminalong]

Concerned about drilling and tapping your exahust manifold to install your EGT probe. Well, read on and ease the nerves.

I did a little experiment, just to ease the nerves and here is what I found.

I used several pieces of angle iron, in various thicknesses, to simulate different spots on the manifold.

Drilling the pilot hole with 1/8" bit

Low Speed Drilling:

1 - Using a new, VERY sharp bit at low speed produced larger pieces and also some spiral fragments. These spiral fragments came up and out with the bit.

High Speed Drilling:

1 - Again, a new, sharp bit, but at high speed and VERY LOW pressure produced nearly NO bits or spirals. Basically just dust

Drilling the main hole with a 21/64" bit

1 - Drilling at low speed produced larger fragments and a more jagged cut.

2 - Drilling at high speed, low pressure produced tiny, tiny fragments and no noticeable spiraling. Almost all fragments were to the outside of the hole. What was inside was dust like.

Tapping the hole - I did this 3 different ways

1 - Tapping with no grease, no vaccum, no magnets produced the largest pieces and these went into the hole. What was produced was larger than I felt comfortable with, but still HIGHLY unlikely to cause any damage at all.

2 - Tapping with a magnet placed near the hole produced similar results as the previous attempt, but all pieces ended up stuck to the inside of the iron where the magnet was placed. Nothing actually fell down to the surface.

3 - Tapping with vacuum and a magnet prodcued no fragments in the hole, everything was either captured by the magnet or sucked up in the vaccum. Very little was even on the magnet.

Results / Recommendations

1 - Drill a pilot hole at high speed, low pressure with the engine off.
1a. Do not drill this with the engine running. If this small drill bit does break, it WILL cause damage.

2 - Drill the main hole at high speed, low pressure with the engine off.
2a. Do not us grease here. This will clog the bit flutes and if it does drop into the manifold, this makes for a sticky abrasive goo.

3 - Tap the hole with either vacuum or the engine running to expell any particles.
3a. Tap to the recommendations of the manufacturer.

4 - If you are not comfortable with the engine running or vacuum, loosen (do not remove) the bolts on the turbo mounting flange and slide a piece of tape (sticky side up) between the turbo and the manifold to catch anything that does fall. Obviously remove this and re-torque the mounting bolts to 24 lb/ft before starting.


Just some observations I made while doing a few test fits.

[Cumminalong]

Okay, you asked for it...

First pic is the vacuum tool that I modded so that I could drill the manifold and have vaccum all around the site. Very easy, very effective.




Second pic is the actual drilling and tapping of the manifold. Sorry I forgot the take a pic of the main hole and I couldn't hold the camera, a drill, and a vacuum attachment to get a good pic, but you get the point. I found that my tap set was too short to use with the vacuum, so what I did was lay the magnet across the exhaust manifold for support and attached the magnet itself to the tap. This drew all the pieces right to the tap an trapped them. Worked friggin awesome.



 

Third pic is the finished install. I still need to dress up the wiring and put the pillar mount on (when it gets here), but no big deal.




Been having fun with this silly bastard all day. On level 1 & 2 during my normal driving, goosing it here and there, running a few hills, I never saw higher than 800 - 850* on the EGT. The only time I saw low 900's was stomping on it just for fun on level 3. Yeah, she moves now!

One thing that is a BASTARD is getting to the key position switch for the turbo timer. This took me longer than the damn EGT probe. You gotta be a friggin contorsionist to get to that plug in the steering column.

Anyways, it's real easy. Took all of 1 1/2 to completely finish.