Just bought a 93 300E and wondering what the normal oil pressure should be?

I was reading about a oil pressure sender. what is the use, and what happends if i don't replace it?

For a cold engine, It can drop to 1.5 with a hot engine.

As I recall a Bar is equal to 14.8 PSI so 3 x 14.8 = 44.5 PSI which is about where it should be.

Looks like your sender is doint it's job OK.

BTW What engine? 2.8 or 3.2? (It helps with questions).

it is a 2.8

The sending unit is bolted to the block and electrically transmits the oil pressure information to the pressure gauge on your cluster. If you turn the key w/o starting the engine and the gauge pegs to "3", your sending unit is bad. If your engine is running and the gauge reads "0", it could also be bad, or you have a serious engine problem!

Note that oil viscosity can affect your readings...but on average, readings of 1.5 and above at idle is normal. But it should peg to "3" when maintaining engine speeds above idle.

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

i just whent out there and turning the key to the on possion and it does go to 3. so the sending unit is the problem?

Yes.

But since yours is a 2.8 (M103 motor) and I have a 3.2 (M104), I can't tell you accurately how to go about replacing it or its exact location. I know the part goes for around $70. I can replace it on mine (did it twice) with 15 minutes of spare time and a crescent wrench...and I'm not a wrench-head!

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

thanks for the help!