Yes, the gauge goes up to 3 bar once you step on the throttle, but what is the actual normal oil pressure? All we know is that it's above 3 bar. I may get an addidional oil gauge and mount it down by the boost gauge. Hmm.....

It actually is NOT above 3BAR, or at least significantly greater than that number. There is a relief valve that bleeds off the excessive pressure, thus limiting it to about 45PSI(3BAR).

Actually 45PSI is probably way more than necessary. The over the road Cummins engines relief valves regulate the pressure to about 15PSI, they say the excessive pressure is unnecessary and only wastes fuel driving the oil pump at such high pressure.

It's normal operation
 

Greetings Speedy,

I guess I am misreading your post. You get 3 bars after stepping on the fuel pedal. Is this when you first start it up or after it's been running and you pull up to a stop light at an idle? It will drop once you get the engine up to operating temps and stop at a light, but will come back up as you accelerate. This also depends on the weight oil that you use as well. If your grade is below 15W-40 I'd expect it to drop sooner because the oil is quite thin by then, after driving that is.

Charles

Oil gauge readings
 

In an attempt to clarify the mystery,mercedes has used the same display for at least 40 years as I recall from driving my 220Sb and 250S etc. The only change has been to go from marking the gauge 15-30-45 pounds pressure to marking it to read 1-2-3 bar. Also somewhere in the 80's MB Americanized,
and went to electric sending units with a wire going to the dash instead of the oil filled line. At any rate when a Mercedes is fired up,pressure should immediately go to 45 or 3 depending on which gauge you have. As the car warms up,the will drop down during coast or idle. Once the car is at operating temperature ( earlier cars just above the 175*F and newer cars just above 80*C )15 pounds or 1 bar during coast or idle. The important point is that any time you even mildly accelerate from coast or idle the needle should peg right away. If you accelerate and the needle meanders to the top or the needle drifts around as you're cruising down the road, you are either low on oil have serious pressure problems. This is how the gauges have acted on the hundreds and hundreds of Mercedes I have driven since 1970.Hope this answers some questions.

Peter
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