I've recently acquired a 300 Sl-24V from 1990. Untill last week the oil pressure gauge always marked 3 bar, no matter the engine temperature or rpm. Last week, at low rpm (or iddle) the pressure started to drop to 1.5 Bar, although it goes back to 3 bar when I accelerate. Is this normal? If it is, why did the engine changed its behaviour? (The car has 125.000 Km; no oil leaks detected and no overheating)
Thank you for your help

Your current oil pressure is perfectly normal. What's not normal is for oil pressure to remain at 3 bar under any and all conditions. It normally does drop to 1-2 bar (sometimes lower) at idle, in gear, with engine warm.

Why did it change? Hard to say. Did you do an oil change recently and change viscosity? Or maybe the oil pressure sending unit was malfunctioning but is now giving accurate readings.

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Steve
'93 400E

It was probably malfuntioning at first. Mine went the other way when it malfunctioned, on the highway, doing 80.....freaked me the hell out !! Pulled over to the side, switched of the engine. It stayed at 3 when I restarted till I got home. After I parked it for awhile it came back to normal operation as you have described. If it acts up again the sending unit will be replaced my heart can't take to much of that kind of shock

yal,

That EXACT thing happend to me. Mine will read 3 then without warning drop to 0 yet the engine is fine. I only had the car a few days and seeing your oil pressure suddenly at 0 while driving can strike a fear in you that no words can describe My 300 will have this fixed next week when it goes in for routine maint.

On one of my 190E 2.3's, I was driving along one day when the oil pressure went from 3 to 0 in the blink of an eye. I whipped over to the curb and shut the engine off.

What I didn't notice was that the other gauges were also not functioning, and I'd simply blown a fuse.

While waiting for the tow truck, I turned the key to "on" to listen to the radio and charge my phone. I noticed the fuel gage also dead, and quickly fixed the problem.

I just about had a freakin' heart attack though!!

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John Shellenberg
1998 C230 "Black Betty" 240K

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