Where's the best place to put my new EGT probe? I'd prefer the downtube because it's the easiest install, but am I going to get acurate reading post turbo?

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RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

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FACEBOOK: PANZER450

Optimal location is pre-turbo I believe. To many questions about the real temperature pre-turbo if it is placed post-turbo.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

"All EGT probes, regardless of application should be installed at a location which would be 1/2 the primary tube diameter from the head surface. So if the ID of your primary tubes is 1.5", the hole or bung should be located .75" from the head side of the flange. You may place it at any angle to allow access to header bolts, etc.
This is a position that's considered a "standard" for location in the automotive world, and allows people to compare apples with apples. "


This is a quote from one of the off-road sites (sorry I can't properly credit or
footnote ). I saved this in my repair folder a couple of years ago. Best description I've seen. Of course, this is pre-turbo location (best).

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Post-turbo has too many variables that can affect it's readings (Turbo temperature, exhaust diameter, turbo A/R, engine load, boost pressure, etc). It's guess work at best as to the maximum safe temperature in a given situation.

In the turbo gas Volvos, the factory seemed to have made a chunk of metal under the exhaust just before it goes to the turbo. That is where I found out they would put a EGT probe.

even though the egr port in the exhaust manifold isnt ideal.. is it reasonable enough (after the egr delete)?

No. The port/tube is 7" long and reaches all the way to the turbo flange.