I'm going to install one in my 300TD soon as well as thinking of relocating the one in my Scout. The issues I have seen discussed are:
Proximity to exhaust valves-closer is better ?
pre vs post turbo- the only argument for post turbo is probe disintegration, but I think that's a rather remote possiblility.
Personally I think that some where in the collector before the turbo is good because otherwise you only know what one cylinder is doing verses what are most cylinders doing.
bb

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For Sale: 1982 MB 300TD
1995 Chevrolet Suburban 6.5TD

Sold: 1980 IH Scout Traveler- Nissan SD33T Diesel

You want a spot in the manifold that sees all cylinders together. before the turbo.....


Post turbo you get a lower reading as much as 200 degrees F lower

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Many think 3-400 degrees lower reading post-turbo. Read a post the other day by someone who had one pre and post. Range of difference was different at different temperatures.
I've just been learning about them recently and I'm surprised more of us on this board don't use them because they seem like the best way to know if you're about to toast your engine.

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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

My pyro probe is installed from underneath (facing up) into the manifold, sligltly angled twoards the turbo (pointed at it). This spot had nice thick iron, is at the point of collection (just past actually) and is about 2 inches from the vanes of the turbine.

Reponds VERY fast to temp changes and seems to be pretty spot on. Remove the manifolds first...is easier

I think that there's little to worry about on a stock set-up. Pulling that manifold just to insert a pyro would be a lot of work for little gain since the overboost switch dumps the ALDA signal at 14 or 15something psi, well before you'd cook a crown.

But, turn the fire up in that IP and it would be mandatory, IMHO.

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Never a dull moment at Berry Hill Farm.

Brandon,
What sort of temps are you seeing on the pyro?

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Never a dull moment at Berry Hill Farm.

Well what conditions do you want?

Stock never EVER broke 1200F...maybe if it was like 110F out with a long hill plus AC on and yeah...maybe touched 1200F.

before intercooler with 3/4-1,1/4 turn fuel adjustment saw 1250-1400 depending upon conditions.

after intercooler with same fuel settings saw 1000-1050F pretty constant unless hot day.

After intercooler with another 1/2 turn fuel see about 1050F-1100F.

After intercooler, same fuel, boost at 14.8psi I see lower temps under a hardcore pull.

When the boot used to blow off the intercooler I would see about 4psi boost, and the pyro would instantly push up to 1500F if you were not careful.

Normal cruising temps are anywhere from 850-950 with medium load and crusing down the road at 75 puts them at about 600 or so F. Mind you this is with modded fuel, intercooler, and more boost (though at cruising it only pulls about 6-8psi at 70mph).

If I am just doing the stock 55mph I see about 400-500F...idle is about 325F with a HOT (after long hard run) floating around 600-900...

So guys...give those turbos a while after to run them hard...its anywhere from 400F-900F at idle in there if you are really reefing on it

I had read an old rule of thumb that said the pyro probe should be the same distance from the head as the diameter of the exhaust vave. That being said; I put it where I could that was close enough. It's about 20 mm. from the cylinder #4 exhaust port (watch the webbing BEFORE you drill )

I can see the advantage of using a more common point of exhaust collection; just passing on what I read and did. Mine works well. FWIW

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The Golden Rule

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

I have had both pre and post EGT probe installations on my work truck. There was never more than 250*F difference and averaged around 200*F difference most of the time. RT

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When all else fails, vote from the rooftops!
84' Mercedes Benz 300D Anthracite/black, 171K
03' Volkswagen Jetta TDI blue/black, 93K
93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K

Eaxctly where I'm planning on installing my probe.

Raising the boost without adding fuel Lowered EGT's?

Yep...

...I think its becuase with the intercooler its pushing more "cooler" air in?...I notice the effect is lesser if the IC is heatsoaked for whatever reason.

Its what I see

The reason your temps went down is because you were having more of a complete burn of your fuel.High temps are from fuel still burning as it leaves the cly.That is why it shot up when you lost your intercooler piping and you lost boost you were then way over fueled.

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89 Ford F3504x4CC 7.3 IDI turboed Intercooler and running on wvo now powered by a 1997 Cumins
87 300SDL on bio and wvo killed by chevy truck 5-24-06
1999 E300TD black with gray int.

Mine's just before the turbo, but installed from the top:

http://www.drivingmissdiesel.com/photos/misccar/709E2937.JPG.html

With boost at ~14psi going up a very hard hill for sustained periods (ie. the Rockies) it gets 1200-1300 degrees at most, normal driving my temps are 600-900.

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'81 300TD Wagon 355k (Miss Diesel)
'83 300SD 180k
'84 500SEL 190k (Parting it out)

I imagine you are only sampling the two cylinders there in the middle right? I thought there was a baffle a long ways down that prevented mixing until just before turbo (ie where I put my pyro)

I don't remember anything like that in my manifold, though it's been a couple years since I installed the probe.

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'81 300TD Wagon 355k (Miss Diesel)
'83 300SD 180k
'84 500SEL 190k (Parting it out)