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  #1  
Old 02-26-2011, 05:04 PM
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Oil pressure

Hey guys I have a question about the oil pressure when I give the car gas the oil pressure jumps up I've 3 and as soon as I let all the way off it drops down to 1 is this normal?

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Old 02-26-2011, 05:12 PM
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Perfectly. The actual oil pressure is well above "3", but the gauge tops out at 3. The best guess we've got around here is that the engineers realized that the low end of the gauge was the most important, and so in the limited dashboard space they focused in on that range.

It's acceptable (depending on year, model, and which edition of the owners manual you get) for it to drop down to 0.2-0.5 bar after a long, hot, hard climb up a 10% grade for half an hour when you idle at the very top and the oil is boiling hot and thin. Under more "normal" circumstances, 1-1.5 bar is a typical idle and anything over 1,000-1500RPM should result in an instant "max out" at 3 bar.

Actual oil pressure at road speed is somewhere in the 6-10 bar range if I remember correctly, but I could be wrong. If the gauge had had that many numbers on it, nobody would even know when it was too low.
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Old 02-26-2011, 06:04 PM
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Great thanks so much for your detailed response. I am selling my benz and the guy that came to look at it last night said that as soon as you let off the gas it should slowly decrease in oil pressure instead of dropping straight to 1-1.5.. He then continued to say that its prolly a loose valve thats causing this.

In my honest opinion the guy was a bit of a nut case in multiple ways.

What do you think of this?

Edit..

Would it help if I got a video?
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Old 02-26-2011, 06:13 PM
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Quote:
Originally Posted by andrewtexas123 View Post
Great thanks so much for your detailed response. I am selling my benz and the guy that came to look at it last night said that as soon as you let off the gas it should slowly decrease in oil pressure instead of dropping straight to 1-1.5.. He then continued to say that its prolly a loose valve thats causing this.

In my honest opinion the guy was a bit of a nut case in multiple ways.

What do you think of this?
I have 2 SD's and neither of the gauges reacted the same as the other prior to me tearing into the engine on one of them. In each, oil pressure was great. Is this a make or break deal for him? Because, unless you're making a killing off the car, despite the guy's nutty behavior, I'd tell him to take it or leave it. There are plenty of other interested people out there that would be more on the normal side that know what the hell they're talking about. As fuel prices skyrocket and people get in on another wave of alternative fuel (i.e. biodiesel), more people will try to swipe these up.
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Old 02-26-2011, 06:27 PM
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I hope your advertising includes the usual ridiculous claims like the motor will do a million miles on WVO !!
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Old 02-26-2011, 10:57 PM
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Originally Posted by mach0415 View Post
I have 2 SD's and neither of the gauges reacted the same as the other prior to me tearing into the engine on one of them. In each, oil pressure was great. Is this a make or break deal for him? Because, unless you're making a killing off the car, despite the guy's nutty behavior, I'd tell him to take it or leave it. There are plenty of other interested people out there that would be more on the normal side that know what the hell they're talking about. As fuel prices skyrocket and people get in on another wave of alternative fuel (i.e. biodiesel), more people will try to swipe these up.
Ok thanks and yes it is make and break for him im sure there are going to be more people intrested but im trying to sell it asap as I need a new alternator for my CRV!

Where else would you list it besides craigslist and here?

Quote:
I hope your advertising includes the usual ridiculous claims like the motor will do a million miles on WVO !!
Haha yep also stated the amazing 35mpg it gets!!
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Old 02-27-2011, 01:51 AM
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Originally Posted by andrewtexas123 View Post
Ok thanks and yes it is make and break for him im sure there are going to be more people intrested but im trying to sell it asap as I need a new alternator for my CRV!

Where else would you list it besides craigslist and here?



Haha yep also stated the amazing 35mpg it gets!!

I understand...unless you advertise it locally in the paper ($$) it sounds like you have it marketed. Good Luck!
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Old 02-27-2011, 11:12 AM
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The oil pressure is normal, the guy just doesn`t know anything about mercedes. NEXT.

Do you have it listed in the Santa Cruz CL? large WVO crowd over here that should snapp it up.

Since you Live here in the Bay Area, why don`t you go to PNP and pull an alternator. they will give you a cross reference as to which cars used the same one. think they are around $35.
from where you are, the yard in Fremont probably the closest on Mowery rd. off 880.

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Old 02-27-2011, 02:23 PM
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In a turbo engine, if the oil pressure drops at idle, it will often drop right to 1.5bar where the piston spray nozzles close, quickly. The spray nozzles use a bit of oil volume.
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Old 02-28-2011, 12:52 PM
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The piston spray nozzles cut off during idle ?
What controls them ?
Where is that located ?
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  #11  
Old 02-28-2011, 01:55 PM
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Quote:
Originally Posted by leathermang View Post
The piston spray nozzles cut off during idle ?
What controls them ?
Where is that located ?

One way you could implement this is by feeding the the squirters with a check valve that opened at 1.5 bar. Dead simple, keeps the bearings from starving if oil falls off for some reason as well.

No idea if this is the actual system or not.
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Last edited by moon161; 02-28-2011 at 02:41 PM.
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  #12  
Old 02-28-2011, 02:15 PM
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RTFM.
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  #13  
Old 02-28-2011, 02:58 PM
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I have never seen anything in my reading which suggested that the spray nozzles quit spraying at idle...
Did I miss something is the question..... ?????
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  #14  
Old 03-01-2011, 05:33 PM
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Yes, the spray nozzles have a pressure valve in them that closes ~1.5bar to maintain better oil flow to other areas at low pressure (and presumably low RPM).
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Old 03-01-2011, 06:14 PM
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Quote:
Originally Posted by andrewtexas123 View Post
Hey guys I have a question about the oil pressure when I give the car gas the oil pressure jumps up I've 3 and as soon as I let all the way off it drops down to 1 is this normal?
This is not normal.

Two common issues:
#1. The oil filter dip tube O-rings are rock hard/leaking.
#2. The oil needs changing.

I would bet on #1.




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