I was driving a short trip, about 1 mile there, and 20 minutes later drove the 1mile back home, and happened to notice the oil pressure remained high even at idle, either all the way up, or just a bit down. I know at idle, it usually drops a lot more than that.

I checked the oil level, and it's perfect.

The manual says the oil pressure at idle MAY drop (doesn't say it WILL drop), but usually the pressure is much lower at idle. Is this a problem?

ADDED TO POST A DAY LATER..... After reading some of the replies, sounds like the 1 mile each way (through a n'hood with stop signs, not just 1 mile straight driving), stopping for 20 minutes to get the pizza, then driving back 1 mile, in 38 degree weather, the engine might have been close, but just didn't get hot enough. Thanks for the replies.

Jeff 1991 300d, 118k

Depends on the ambient and engine temperatures. Sounds pretty normal to me for the cold viscosity of the oil to not thin down much on such a short trip. What was the temperature in your location? Engine temperature at end of trip?
On a longer trip in the next while if the hot idle oil pressure returns to what it was everything is normal in my opinion.

The pressure is dropping quite a bit at idle, but you can't see it because the gauge is pegged at 3 bar while you're driving.

Did you just do your oil change?

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if your car wasnt up to op temp yet thats why.

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The temp in Atlanta was about 38 at the time. The car was at full operating temp, though maybe barely so, after 1 mile of driving. The temp was right at 80, I think. I did not do an oil change recently.

Thanks,

Jeff

If your engine is cold your oil pressure is pegged at the max the relief valve will allow until the engine 'and' oil warm up... Give it 3 to 5 miles before you see a pressure drop and about 15 to 20 before your oil is at full operating temp... YMMV...

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Them there new diesel's get to operating temps in a mile!! I gotta get me one of them.

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Look at your Oil pressure gaguge with the ignition ON, but engine OFF. It should be a Zero. If its pegged at 3 then you have a defective oil preassure sending unit.

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'95 E300 Diesel, 264,000 Miles. [Sold it]

1 mile is no where near enough time to heat the oil up to operating temp, even if the engine coolant has reached proper temp. If it stays at 3 at idle after 10+ miles of driving then I would be suspicious of the pressure sending unit. Otherwise, on a short trip that is perfectly normal, especially at 38F.

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can be a broken ring/ hole in piston if pressure doesn't drop at all. I had that in my (now died) '80sd...

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Somehow I doubt this is the problem. A hole in the piston would result in poor running, a knocking noise, and massive blowby and oil consumption.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

In my 240D, once the oil gets up to pressure (2-3 sec after starting) my pressure stays pegged at 3 always.

In the 300TDt, the oil pressure will drop to about 2bar at idle, but immediately back to 3 when I tap the gas. I have read others say this is normal behavior. Both cars run great, and so I always thought maybe the difference as in the operation of the 616 vs. the 617?

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From what I'm reading, it looks like the basically 2 mile drive was not enough, in 38 degree weather. I did go 1 mile, then sit for 20 minutes, then go back home the other mile.

Thanks,

Jeff

Zeke --

I have had 2 - 240Ds, and both of them had lower pressure at idle with the oil hot. If you don't show that, driving in San Antonio, I would assume something is awry -- starting with the OP sending unit, or gauge.