One major concern of a pre-turbo EGT probe install for alot of people is related to iron shavings damaging the turbocharger. The following are the currently used tactics to keep metal shavings out of the turbo:

1. Remove the turbo charger and/or exhaust manifold.
2. Idle the motor while drilling to force the shavings out of the drilled hole under exhaust pressure.

I use a method using the same principle as idling the motor, but instead I use a shop-vac set on "blow" instead of "suck":

A. Put a clean sock or clean rag over the end of the shop-vac attaching it using whatever works best/easiest for you. (hose clamp, duct tape, etc.)
B. Remove intake hose and insert shop-vac hose to blow through the intake. (Obviously, make sure your shop-vac is blowing clean air so you don's blow a bunch of crap into your motor.)
C. At least one of your cylinders should have both exhaust and intake valves open, allowing air to blow through your motor and out the exhaust. You can verify this by putting your hand over the end of the tail pipe.
D. I also put a sock over the tail pipe in order to create some back pressure to be sure to force iron particles out of the hole that I will be drilling.

I do them by greasing the drill bit and then the tap. LOTS OF GREASE! The bit will tend to pull the cuttings up and out of the hole and the small shavings from the tap easily lodge in the grease on the flutes of the tap. When I put my Edge tuner in the Dodge/Cummins that's what they recommend as well. Works great and is dead easy. I do use the vacuum before I touch anything after drilling and after tapping just to make sure that nothing is pushed into the hole. And remember that the hole is downstream of the turbo so it will try to push any remaining bits into the exhaust system.

Dan

Any EGT gauge, if you want it to display a good reading is to put the sensor right where all of the cylinders collect, which just so happens to be pre turbo in our case. Putting it post turbo will give lower than actual readings since the turbo soaks up a bit of heat

If you disable EGR, you can use the port for an EGT probe without drilling. It's a central location in 602 and 603 manifolds. It looks like it's also central in a 617 manifold if doesn't mix with the #1 runner but it might be considerably cooler at the EGR flange unless you can get a probe all the way to the turbo flange.

Here's Jeremy's work on a 603.960 - Ashtray gauges for the W124

Sixto
87 300D

I am not sure where you are drilling; if near the Turbo the Turbo can be removed.

If you Grease the Drill Bilt you need High Temp Grease and you need a variable speed Drill Motor to turn the Bit slow. Even then some of the Grease may Melt.

However, Gease works well on the Tap if you fill the Flutes/Grooves with grease.

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84 300D, 82 Volvo 244Gl Diesel

I've generally put them immediately post-turbo. True that the turbo soaks up some heat but I suspect that what you really need to know is the temo at cruise and the temp under a big load (going up hill, running a mile at WOR (Wide Open Rack) like on a race track). It's the heat increase that's worrisome to me. I like to keep the Cummins below 12-1300 *F.

Dan

If you're running 12-1300F post turbo you might have piston melting issue soon.

I will be installing a pyrometer into my superturbo 606 manifold pre turbo for peace of mind.

All the Pyrometers I have seen on Engines have been before the Turbo.

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84 300D, 82 Volvo 244Gl Diesel