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1995 Mercede-Benz S500
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Discussion Starter #1
Sooo some of you havent heard i bought a 95'S500 and ijsut got done rebuilding the motor. We finished the installation this morning and everything was fine. As of now i took it for a short test drive and i notice the Economy gauge is out of whack.. its is not responding like how it normally does when you step on the pedal. Now i see that the oil pressure gauge level has dropped and is not holding pressure at (3)psi like how it normally should. I went ahead and use the Castrol 5-30 Synthetic motor oil. Now im wondering if its the synthetic oil that is causing me to lose oil pressure? Or maybe its the oil pressure switch. I changed almost every internal part besides the oil pump and the oil pressure switch.
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
Sooo some of you havent heard i bought a 95'S500 and ijsut got done rebuilding the motor. We finished the installation this morning and everything was fine. As of now i took it for a short test drive and i notice the Economy gauge is out of whack.. its is not responding like how it normally does when you step on the pedal. Now i see that the oil pressure gauge level has dropped and is not holding pressure at (3)psi like how it normally should. I went ahead and use the Castrol 5-30 Synthetic motor oil. Now im wondering if its the synthetic oil that is causing me to lose oil pressure? Or maybe its the oil pressure switch. I changed almost every internal part besides the oil pump and the oil pressure switch.
try the oil pressure sending unit(i think thats what its called) also while the engine was out you should have just swapped out the oil pump and chain for it.

i am guessing you dropped the oil pan and cleaned the strain thing
 

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1995 Mercede-Benz S500
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1,175 Posts
Discussion Starter #3
Yeah i know i should ahve just bought a new oil pump.. damnn. I went ahead and ordered a new oil pump.. 27 from a german import supplier. Hopefully that will take care of it. Before we torn down the car it was running fine but had minor leaks here and there. We swapped out the oil pressure for a temp one off another spare motor that we had and the oil pressure is sitting at 1.5. Do the oil pressure stays at (3)at a stand still idle?
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
once the engine is fully warmed up and after some very high revs it can sit anywhere from 1-3bar. aslong as by 1500rpm its above 3bar it is considered good. by the way the recommended oil in hot temperature is w40 oil.
 

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1995 Mercede-Benz S500
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1,175 Posts
Discussion Starter #5
i see. before my last w140 started running bad i remember my oil light would stay around 3 at idle.. like you said maybe its just havent warmed up. Now on top of the oil... my transmission isnt shifting... damn.
 

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1996 Mercedes Benz S500 sedan,1997 S500,2012 s550
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54 Posts
Just curious,when you say you rebuilt the motor did you replace all of your crank bearings?
Or was this more of a freshen up of the motor?
I have found that most times when you have low oil pressure it is because bearings are wore out.
 

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2003 S55 AMG Kompressor
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361 Posts
You are aware that you have to prime the oil pump (fill it with oil) before re-installing it ? low oil pressure is one of the symptoms, catastrophic engine failure another
 

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92 500SEL to 01 E320T current 2014 lexus LS460
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3,886 Posts
The 500 has a two stage oil pump, cold oil at idle is arund 2-3 after warm up it should hover around 1+, but at 1500 rpm and above it should be at 3, synth does not change things.
 

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1992 500 SEL; 2000 CLK 430 CONV. 2000 BMW 740 BMW
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94 Posts
oil pressure

once the engine is fully warmed up and after some very high revs it can sit anywhere from 1-3bar. aslong as by 1500rpm its above 3bar it is considered good. by the way the recommended oil in hot temperature is w40 oil.
500 sel

when the speed goes 60 mph oil pressure goes to cero and red light turns on let the speed go down and the pressure goes back to 2 bar

replace the plastic rubber funel in the bottom off the oil pump and still does
it replace oil level sensor and check valve in oil filter oil pressure switch??
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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500 sel

when the speed goes 60 mph oil pressure goes to cero and red light turns on let the speed go down and the pressure goes back to 2 bar

replace the plastic rubber funel in the bottom off the oil pump and still does
it replace oil level sensor and check valve in oil filter oil pressure switch??
The oil pressure doesn't have to do with speed, it has to do with the rpms. Best way to be sure is to get a mechanic to hook up a manual gauge. My bad but i just didn't understand this question.
 

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1992 500 SEL; 2000 CLK 430 CONV. 2000 BMW 740 BMW
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94 Posts
oil pressure

The oil pressure doesn't have to do with speed, it has to do with the rpms. Best way to be sure is to get a mechanic to hook up a manual gauge. My bad but i just didn't understand this question.
60 mph or 2500 rpm the neddle on the presure goes to cero and red light turn on let go off the gas pedal and the pressure goes back to 2 bar
 

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1995 Mercede-Benz S500
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1,175 Posts
Discussion Starter #14
^^^ I was going to installa manual gauge but the screw-in head was too big. I did get in my new oil pressure switch and hopefully that should help it out. Oh as the oil pressure hovering over 1+ the car is doing that so i guess the oil pressure is fine. Just as long as i dont see it drop back below the 0 and seeing that red light.

Just curious,when you say you rebuilt the motor did you replace all of your crank bearings?
Or was this more of a freshen up of the motor?
I have found that most times when you have low oil pressure it is because bearings are wore out.
Oh i meant refreshing up the motor. The original idea was to take the motor out of the "current" spare car and install the motor back into my 93'. But we figured that this car has better interior and its a 95'. So we just decided to change out some minor gaskets. Which turned out to be just about taking the car apart.
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
^^^ I was going to installa manual gauge but the screw-in head was too big. I did get in my new oil pressure switch and hopefully that should help it out. Oh as the oil pressure hovering over 1+ the car is doing that so i guess the oil pressure is fine. Just as long as i dont see it drop back below the 0 and seeing that red light.



Oh i meant refreshing up the motor. The original idea was to take the motor out of the "current" spare car and install the motor back into my 93'. But we figured that this car has better interior and its a 95'. So we just decided to change out some minor gaskets. Which turned out to be just about taking the car apart.
what is this red light everyone is talking about? i have never seen it. i don't think my 97 has a red light
 

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1992 500 SEL; 2000 CLK 430 CONV. 2000 BMW 740 BMW
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94 Posts
I found the problem bad serpentine belt tensioner and replace the battery and the problem is fixed sliping belt ...
 

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W140 1998 S320
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299 Posts
Friends I had this problem and I don't know where the issue is in the pump or something else's beside low pressure sometimes I noticed one day that the pump actually don't work until I rev it


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