Egt probe install [Archive] - Duramax Diesels Forum


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08-31-2008, 01:43 AM
Thought I'd try this DIY, EGT PROBE INSTALL.


5/8" open end wrench
Standard and Phillips head screwdrivers
Needle nose pliers
Drill motor
3/16" drill bit(optional-I used as a pilot hole)
7/16" drill bit (only if you using a 1/4" NPT tap)
Tap Handle
1/4"NPT tap
Heat gun-or flame thrower
Heat shrink tubing
Anti-seize lube
Drill lube-I used wd-40...
1. Yes here in Texas a fan is the first thing to grab and put next to ya. Ha

2. After looking at the clearance behind the passenger fender well to the exhaust manifold, I opted to jack the truck up and take the tire off. Now I dont have to reach over the darn tire and cut threads for my first time. So, grab a jack and jack stand and lift her up.

3. I grabbed a flat head screwdriver and pulled the plastic rivets from the fender well. I could get them partially out from the fender, then I changed to the needle nose pliers and jerked them the rest of way out. Notice there will be other plugs attached from the inside. I just pushed them through with the screwdriver.

4. The fender just comes out easily, showing all the goods.

5. Sorry for the blurry darn pic. When u get close, you can see that the manifold has a small flat spot from the left end to about 2 1/2" out.

6. Just place the bottom of the thermocouple insert within the flat spot and mark her. I did the 2 1/4" measurement and it was right on when I placed the thermocouple insert within the flat spot.

7. I started the truck and then sprayed some wd-40 on the drill bit and on the exhaust manifold. I started out with a 3/16" drill bit for a pilot hole. I started very slow to just draw chips as Ive read from other DIYS and it worked very well. I would draw some shavings and then wipe them off. Then I found out you dont have to wipe them off, because once you drill inside, the exhaust comes out hard enough to wipe her clean with out any assistance! Oh and it sounds pretty cool. The manifold is such a soft metal, you dont have to use hardly any pressure to draw shaving, so just get in a comfortable spot and start slow.

8. Then I changed to the 7/16" drill bit, since I will be using the 1/4" NPT Tap (it recommends the above drill bit). Make sure you dont buy a NC tap when it asks for a NPT tap. Just pay attention and grab whats required by the egt probe you are using. I squirted some wd-40 on the drill and exhaust and just started slow. I stopped midway and checked the drill bit. It was pretty hot so I sprayed her down again and went back at it.

9. I was lost on how to tap this hole. The exhaust was getting to hot to place the tap in the hole and slow start cutting threads, so I turned the engine off. I dont know if this was because I was in my garage and it was 90plus today with poor ventilation(truck was half way in the garage).. After the truck cooled down, I started it back up and went after it. I learned that you dont have to press as hard as you can on the tap. It cuts on its on and you just have to use a sturdy hand to keep the tap perpendicular to the hole. It is very easy to tell when the tap stops turning, just back it about a 1/8 turn and got back at it til it stops and continue the process. After getting a couple grooves in, I would turned the tap all the way back out and clean the grooves. I thought I would get shavings in the groove and start cross cutting. Hey my first time and I did not want to mess up. I cleaned the grooves and very slowly put the tap back in position to start cutting again. Dont jam her in there and start cross cutting. I dont know what you would do if this happens. Anyways its stress free if you take your time. After you gone a ways, take it out and place the thermocouple insert in and check to see if it will sit properly. Once you are able to screw the insert in, take it out and apply the anti seize medicine on the insert and insert it into the manifold. I used a 5/8" open wrench to snug her up. Remember the metal is soft, so dont put any weight behind it when tightening.
11. Attach the probe. I place anti-seize on the probe nut also, but I dont know if I should have done this. My neighbor stopped by bout' that time and said he would... Now you figure out how you want to wire the thermocouple. The thermocouple will have about a 6in" lead on it. I have a Banks box, so I just ran the wire from the box to the probe. Place heat shrink tubing onto the wires to cover the splice between probe wire and the wires from your gauge or box. Heat shrink now, because you will be hiding the wires now to wherever you place them. Some follow the wiring up front, I just used the firewall with zip ties. I dont like the wire being exposed and will have to think of another way to hide this wire. Doesnt look good to me, but will work for now.
12. Ha, now place the fender back in place and try and place all the plastic rivets back with out one being lost. I actually still had each one and got them all in. I even reached inside and placed the other plugs back in place on the fender. First time to not have extra parts or break the little plugs.

Well, I attached the other end of wire to my box that has a lead. I placed the heat shrink over the splice but did not shrink it. I placed black electrical tape on both ends, so I can still take my box off when I need to...:secret:

Hope this helps. First DIY, so help a brother out if I missed something or need to add something to make it easier for the next.

08-31-2008, 06:52 AM
Nice write-up :D

08-31-2008, 07:36 AM
If the exhaust is getting too hot when tapping you can shut the motor off and use a small magnet with a flex-head to get down in there and pull out any chips from the tap.

08-31-2008, 08:41 AM
Nice write-up :D


10-05-2012, 10:32 AM
Just curious...would the egt temps be different ( passenger vs drivers )?

06-01-2013, 05:05 AM
Nice write up, doing this today on my LB7

06-02-2013, 01:01 PM
Great write up with pics and info!

06-02-2013, 01:35 PM
I just did it with the motor off and used a small magnet that fit inside the hole when done to get all the shavings out.

06-02-2013, 05:04 PM
wow, I seriously did this today this morning and then saw this afterwards, at least i knew what to do. but it is a very nice write up indeed.

09-20-2013, 11:13 PM
Do you have to put this in the passenger side? I just got the full bore driver side manifold and it already has a tapped hole in it for the egt probe. I know the stock drivers side flows about 80% of what the passenger side does, but with the aftermarket one does it matter which side it goes on? Or passenger side cause its further from the turbo is what I've also heard????

09-21-2013, 06:22 AM
Sub - Nice write up