Hole in Range-4 Turbo output "L"

[PNM]

Some time back I experienced some exhaust coming from my insulation covered port turbo exit flange.

Upon closer look I found major deterioration to the bolts, flange, etc.

I removed the "L", replaced a couple of studs in the turbo exit flange, and cleaned up the "L".

I reinstalled and re-insulated.

It worked great, until I noticed a small amount of exhaust smoke behind the port engine when the engine was running .

I recently removed the insulation and discovered a puff of exhaust smoke coming from the "L". Upon closer inspection, I found a 3/8" perfectly round hole with no threads showing in the bottom of the "L".

Did I leave a plug out? Is this a drain valve location?

I can fix it by tapping it for 1/2"- 3/4" long bolt, but I would like to know if any of the members know what belonged in the hole???

 

[PNM]

FYI! I found a used replacement "L" and it has a metal extrusion with a plug in it extending from where I have a hole. I don't need to attach anything to my exhaust output, so, I just drilled and tapped at 5/8" and put a plug in it. Then I sealed the "v" clamp joint with high temp exhaust gasket maker and walla!!! not a hint of smoke when she's running.

Now I just need to re-wrap the very hot "L" with some kind of insulation, and we're done.

 

[Greg QS]

Probably a port for a EGT probe.

 

[PNM]

Good point.

 

[twistedtree]

Agreed. But I’d expect it to be tapped