Hmm...Where do i drill a hole for EGT probe?? - Page 2 - PeachParts Mercedes-Benz Forum

#16 01-05-2009, 02:29 PM

Right, post turbo is only good for estimating operating efficiency. Its nowhere near accurate or responsive enough when modifying engine performance and pushing thermal limits.

Jeremy5848 · #17 01-05-2009, 02:31 PM

Quote:

Originally Posted by TheDon

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

Where is yours?

Actros617 · #18 01-05-2009, 04:13 PM

maybe i could do a downstreme and adjust the.... "THE NEEDLE" MAUAAHAHAHAIAHAAA!!! but i be breaking a $100+ gauge and it wont be as accurate

!!!

KarTek · #19 01-06-2009, 08:41 AM

They do make post turbo pyro's like this:

http://www.isspro.com/proddetail.php?prod=R3607VW

But like, FI said, it's not a great location for accurate measurement. Also, you'll probably end up with more wire than you need to do the install. DON'T CUT IT! Just coil it up somewhere. It's calibrated.

cell · #20 04-07-2009, 03:56 PM

I'm about to head over to german starr motors in austin and pick up a junk manifold so i can drill and tap it for a thermocouple.

they want $75 for the manifold. pick-a-part's price on manifolds is $20, but that would involve a trip from austin to san antonio and several hours of labor. so whatev.

cell · #21 04-07-2009, 05:42 PM

well, it wound up being the wrong manifold (it was off a later model with EGR, and while that would probably work, I don't want to deal with explaining to any inspection places about why my EGR is missing), so I passed on it.

however, now that i've been able to take a good look at a complete exhaust manifold / turbo assembly removed from an engine, I realized there's no reason i can't just mount the thermocouple in the turbo housing. removing just the turbo sounds like much less of a chore. reading back through this thread I see this was mentioned earlier, but I missed it the first time around.

Simpler=Better · #22 04-07-2009, 06:04 PM

So long as the EGT probe doesn't find it's way into the turbine....

snookwhaler · #23 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.