If you pull the fuel/oil/temp gauge (atleast on the w124) there is a dash pot behind the face, anyone know what it is for? I am trying to determine if its for the oil pressure gauge. My oil pressure always reads high and I am starting to wonder if its the wiring and if this is an adjustment..

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

You mean a potentiometer?

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

Some gauges have a damper so the pointer doesn't register every blip but such would be part of each gauge mechanism. As compu_85 asks, do you mean the potentiometer to adjust gauge cluster illumination?

Do you mean the gauge pegs at 3 while glowing? Might be a bad sender.

Sixto
87 300D

Bad sensor on the 124 means gauge pins at 3 and stays there whenever you have power.

It is very easy to change (Once you get back there). A negligible amount of oil will leak out when you remove it. Don't forget to pick up the crush washer too, it's not included with the sensor.

When I changed mine out, I removed the IM and it was a piece of cake. Others say you don't have to remove the IM.

One other caution, the big nut on the starter with the + battery cable is right below the area you are working in. I would definitely disconnect the battery before putting a wrench down there.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Trim pot not dash pot. Sorry. Turns out its for the fuel gauge. The later models do indeed have dampening to prevent the flickers.

Pressure always reads around 2 at hot idle. It must be the wiring at this point. I'll check the resistance next time I get under it.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

My oil pressure gauge sender has a dead spot around 1.2 bar :/ I need to replace it.

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

X2!!!! from personal experience!

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

So does mine. I don't think it's a problem with the gauge or actual oil pressure.

Sixto
87 300D

Mercedes electric oil pressure gauges seem to all be optimistic. Mine (1995 E300) also reads between 1 and 2 bars at hot idle while the actual oil pressure (VDO mechanical 0-100 psi gauge) reads between 15 and 20 psi or 1+ bar. If your gauge immediately climbs above 3 bar at cold start and at any engine speed above 1000 RPM it is working correctly.

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970