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  #1  
Old 05-07-2008, 01:54 AM
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Pressure gauged maxed out, WHY

What should I be looking at first when my pressure gauge jumps to max (3) when I start the car? I know alot of MB do this, but why? Should I start by checking the sender unit or the gauge? Is these really a problem or I'm I making something out of nothing.

Any help would be great.
Thanks

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  #2  
Old 05-07-2008, 02:17 AM
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Your making something out of nothing. The Oil pressure gauge (i'm assuming) is always pegged on cold start up. once warm, it should be around 2 bar until you punch the gas, then it will be 3 agian. Nothing to worrie about, just regular operation.
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  #3  
Old 05-07-2008, 02:49 AM
ForcedInduction
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Pressure gauged maxed out, WHY?

Because that is how it works.

When it ISN'T pegged when the engine is cold or above idle, is when you should start to worry.

Last edited by ForcedInduction; 05-07-2008 at 05:07 AM.
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  #4  
Old 05-07-2008, 05:01 AM
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your worried about 3 bar cold idle psi? 1 bar = 14 psi. So your worried about (at least) 42psi cold idle oil pressure? If anything, this is good and a blessing just sit back and enjoy it. On my list of things to worry about, high cold oil pressure is right below "did my diesel come from tortured dinos?"
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Last edited by Cervan; 05-07-2008 at 05:11 AM.
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  #5  
Old 05-07-2008, 08:25 AM
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I only wish MB had put a proper gauge on there that actually showed what the pressure is... I like to know.
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  #6  
Old 05-07-2008, 08:28 AM
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i would have thought someone that has been registered since 2005 would have seen this question come up a few times and already know the answer
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  #7  
Old 05-07-2008, 08:38 AM
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I have to admit I have often questioned the wisdom of M-B's design of the oil pressure gauge scale but some things they do just defy logic or wisdom. The serenity prayer comes to mind.

For example, on our brand new C300, they have a temp gauge which they have thoughtfully put in the same location as the fuel gauge is on my E300 and reversed the fuel gauge to be where the temp gauge was...while that isn't disorienting enough, they have the car running at 90C but still have 80C as the "horizontal" spot on the gauge...so it always looks like it is running "hot" even though it is designed to run at 90C (at least that is what I have been told) so the needle never points at or near the horizontal position but always looks to be high to people used to the old style where 80C was normal and at near horizontal...again, just an annoying issue they should have addressed but didn't.
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  #8  
Old 05-07-2008, 10:25 AM
92 300D 2.5L OBK #59
 
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Quote:
Originally Posted by nhdoc View Post
they have the car running at 90C but still have 80C as the "horizontal" spot on the gauge...so it always looks like it is running "hot" even though it is designed to run at 90C .

When I flew in P-3 the Flight Engineers used to rotate the gages so the lines all looked normal (straight across). Easy to spot something out of place with 50 or so gages. LOL

You could always go with an aftermarket something like this:
http://www.glowshiftdirect.com/index.asp?PageAction=VIEWPROD&ProdID=259

Scroll down and you'll see they also offer EGT Gauges and others.. Nice..
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  #9  
Old 05-07-2008, 10:25 AM
KCM KCM is offline
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Heck, most people who buy new Mercedes cars wouldn't have any idea how to read a gauge. All they respond to is a bright red warning light, and even then they will continue to drive until it blows up thinking, "I can get to my destination, can't be that important." You're lucky Mercedes still feels gauges are important enough to install.
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  #10  
Old 05-07-2008, 10:49 AM
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Quote:
Originally Posted by vstech View Post
I only wish MB had put a proper gauge on there that actually showed what the pressure is... I like to know.
Amen to this. I've heard the old "A gauge reading that low on a full scale, even if it's normal, would make people think it was too low" argument before... but I want to know too, just to satisfy whatever need it is to know exactly what's going on .
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  #11  
Old 05-07-2008, 12:41 PM
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>>know exactly what's going on

Why? Once you've got over 3 Bar of oil pressure, that's plenty. How would it affect any driving decision to know whether the oil pressure is reading 3.5 or 3.7 Bar. I like the pegged needle, it's much better than having a needle yo-yoing back and forth.

Also, having a 3 Bar range allows the gauge to be more accurate and sensitive for reading the low pressures when things do become critical. I'm happy that my gauge would allow me to check to see if I have over 0.3 Bar at hot tickover, where a full scale reading gauge would never provide that sort of (useful) information.

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