Hmm...Where do i drill a hole for EGT probe?? - PeachParts Mercedes-Benz Forum

Actros617 · #1 01-04-2009, 11:23 PM

I am planning to get a EGT soon, I need to know where is a good place to drill in for my EGT probe??? What do you use to seal around the probe, jb weld?? Welding it back???

Jeremy5848 · #2 01-04-2009, 11:26 PM

Which car? Tapped holes should already exist, no drilling required.

Actros617 · #3 01-04-2009, 11:30 PM

oh i am doing it on the 1984 300SD, i dont see a taped hole??? I there a bolt in the taped hole???

#4 01-04-2009, 11:48 PM

Drill and tap here.

Actros617 · #5 01-04-2009, 11:55 PM

must it be under??? I dont think i have the space to do that kind of drilling... although i can take the manifold out but i its a hassle to take it out b/c of the turbo and oil for the turbo and oil drain tube... can i just drill on top of where you have shown but i still have to remove the manifold!!!! darn...

#6 01-04-2009, 11:58 PM

The turbo MUST be removed anyways. The metal shavings would damage it.

Actros617 · #7 01-05-2009, 12:01 AM

is there another place that i could place it...

#8 01-05-2009, 12:05 AM

The turbo housing.

No matter where you decide to drill/tap for EGT, the turbo has to come off. There is no way around it.

...and no, the EGR tube won't work...

Actros617 · #9 01-05-2009, 12:22 AM

man this is going to be a tough one

,is it hard to remove that exhaust manifold???

TheDon · #10 01-05-2009, 12:31 AM

not really. Its just involved and you need a new gasket when you put it back on.

oh and dont screw up the oil lines for the turbo. If I were you I'd get a manifold from a junkyard and have it drilled/tap'd and ready to swap in.

KarTek · #11 01-05-2009, 10:01 AM

Now, this is not a "best practice" but I've seen a lot of guys do this on their trucks. They drill and tap the hole in place on the truck but they coat the drill and tap with grease and hold a small speaker magnet up against the tool while drilling and tapping to keep the chips out of the manifold. Like I said, not the recommended practice and all...

Also, when you tap the threads, only run the tap down a little way into the part - maybe 3/8". The pipe thread is tapered and if you run it in too far, the probe fitting will bottom out and could leak. When the probe holder is installed, you should see about 1/8" of threads still remaining exposed.

snookwhaler · #12 04-07-2009, 06:05 PM

Quote:

Originally Posted by KarTek

Now, this is not a "best practice" but I've seen a lot of guys do this on their trucks. They drill and tap the hole in place on the truck but they coat the drill and tap with grease and hold a small speaker magnet up against the tool while drilling and tapping to keep the chips out of the manifold. Like I said, not the recommended practice and all...

Also, when you tap the threads, only run the tap down a little way into the part - maybe 3/8". The pipe thread is tapered and if you run it in too far, the probe fitting will bottom out and could leak. When the probe holder is installed, you should see about 1/8" of threads still remaining exposed.

I have done my past 2 trucks this way. Several of my friends have done it too. This includes about 34 other trucks that I have helped do this on. All Cummins though. I have done it with the grease and a steady hand with the engine running. This way the shavings blow out of the manifold. It is just about impossible for shavings to find there way to the turbo. I always marked the manifold and used a punch to "mark the spot" so you can place the drill bit while the engine is moving. Doing it slow and letting the drill bit do the work makes it easy. Just pull the drill every couple turns remove the shavings and re-apply the grease. Once you are through the manifold you wont have to worry about the grease. It will be blowing like mad.

Personally on the 617, I would pull the manifold for 3 reasons. 1 is so you can clean the intake, 2 is to check the oil drain to check and fix any leaks and 3 so you can mount the thermocouple underneath of the manifold. This just makes since because it looks like mounting above would cause some interference with the air cleaner assy.

You always want to mount the thermocouple in the collector. Preferably near the center if the manifold has the strength to drill and tap there.

Be sure not to be overzealous with the tap or you will not be able to tighten the thermocouple properly. You want it "tight" in the manifold.

You also want to be sure to install the thermocouple at the right depth. There are quite a few different varieties out there.

Simpler=Better · #13 01-05-2009, 10:59 AM

2x Get a junkyard manifold, you should be able to get one for ~$20.

Don't forget to "fix" the EGR while the manifolds are aff

Jeremy5848 · #14 01-05-2009, 11:30 AM

Perhaps it's only the '85 California OM617 engines that came with a tapped hole? It was designed to allow measurement of back pressure (= plugged trap oxidizer) but makes a great mounting place (at the rear of the exhaust manifold) for an EGT probe. Alas if the Federal versions do not have that tapped hole.

BTW, the OM603 engine in the W124 300D Turbo also has a tapped hole in the exhaust manifold. It's at the front of the exhaust manifold, near the turbo dump valve. In the following picture, you can see the bolt that plugs the hole in the rust-colored manifold, just to the left of the valve cover breather hose. The OM617 is similar but placed at the back of the manifold.

Jeremy

TheDon · #15 01-05-2009, 12:42 PM

thats not a very good place for EGT's since its coming off once cylinder.