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  #1  
Old 04-27-2013, 02:40 AM
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jumping oil pressure

the other day i was sitting in a drive through and my car got up to about 100-105c, in need of a coolant flush, and i noticed that my oil pressure gauge was jumping up and down pretty fast. i was wondering if this means its going out or that my oil pressure is really jumping around. this is a mechanical gauge btw.
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  #2  
Old 04-27-2013, 07:33 AM
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Quote:
Originally Posted by benzdude42 View Post
the other day i was sitting in a drive through and my car got up to about 100-105c, in need of a coolant flush, and i noticed that my oil pressure gauge was jumping up and down pretty fast. i was wondering if this means its going out or that my oil pressure is really jumping around. this is a mechanical gauge btw.
Its normal when the oil is hot to get those. I think its just mechanical vibrations not being damped out by the oil in the tube to the gauge.
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Old 04-27-2013, 09:15 AM
t walgamuth's Avatar
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Well, I'd ask how much was it jumping and how often....was it like a vibration or an erratic heart beat?
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Old 04-27-2013, 12:44 PM
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Quote:
Originally Posted by benzdude42 View Post
the other day i was sitting in a drive through and my car got up to about 100-105c, in need of a coolant flush, and i noticed that my oil pressure gauge was jumping up and down pretty fast. i was wondering if this means its going out or that my oil pressure is really jumping around. this is a mechanical gauge btw.
You did not say if the Oil Pressure fluctuation was at idle or higher rpms?

You 84 300SD I believe has an Electronic Oil Pressure Gauge. If so the Sending Unit will be at the bottom rear of the Oil filter Housing.

A fluctuating Gauge could be a symptom of a loose connection at the Sending Unit or a Sending Unit going bad.
It could actually be the Sending Unit and the Gauge are working OK and you are really having an Oil Pressure issue.

If Oil Pressure issue is happening at Idle it could be the two 6mmIDx10mmODx2mmW O-rings at the bottom of the Oil Filter Tube need to be changes or something is trapped in the Spring loaded Valve inside of that Tube and keeping the Valve open.

Compress Air can be blown through the little hole at the top of the Oil Filter Cap Tube to try to blow out anything in the Valve at the bottom of the Tube.
The O-rings can simply be replaced.

When you have Oil Pressure issues the ideal thing to have would be a Test Gauge that you can hook up to verify what the Oil Pressure really is. But, you need to fabricate the set up for that.
Also the Oil Pressure on your Engine has the possiblity of being as high as 110 psi.
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Old 04-27-2013, 02:22 PM
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It could mean you have a grounding problem. I added a ground from one of the fasteners that hold the three sections of the instrument cluster together which fixed my "jumpy gauge" problem.
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  #6  
Old 04-28-2013, 01:00 AM
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It's a 300sd motor in a 1985 300d someone made my tag that and I don't know how to change it. I think it's the motor shaking because it doesn't do it unless she's shaking from my low idle.
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84 300sd 2.47 dif 360k
26 mpg needs lots of love
given to me in pitty

89 civic hatchback auto 140k
33mpgs soon to be low to mid 40's
been in the family since mile 1

85 300d with unknown knock. driven over 30k with knock and still going. sold for $800
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  #7  
Old 04-28-2013, 12:02 PM
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Quote:
Originally Posted by benzdude42 View Post
It's a 300sd motor in a 1985 300d someone made my tag that and I don't know how to change it. I think it's the motor shaking because it doesn't do it unless she's shaking from my low idle.
To change the Signature click on your Member Name.
When the page opens up at the far left upper Corner is "User CP"; click on that and on the left of the page is a Menue with various choices.
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