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Old 05-16-2016, 11:59 AM   #1
NSX7
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Join Date: May 2016
Location: Toronto
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oil light on when idle



98 M3 with 168,000 kms

recently bought the car - did not have maintenance history with it - recently replace the oil and used 5W/40 synthetic liquimoly oil

oil light comes on when idle after long drives (engine hot) and the light goes away when I tough the gas.

The car came with aftermarket gauges. When cold, the oil pressure reads 10psi - as the car gets hot, it goes down almost a half point which could mean 5 psi or less - and when accelerating, it is @ 55 psi whether hot or cold

I had done some reading into this - and there are too many theories out there

Has anyone had this issue and it went away by simply replacing the oil pressure switch? or is it too simple to be true?
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Old 05-16-2016, 12:54 PM   #2
Blackedout95
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Its a start (the switch) here is a good discussion on it...

http://www.bimmerforums.com/forum/sh...e-PSI-in-99-M3
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Last edited by Blackedout95; 05-16-2016 at 12:56 PM.
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Old 05-18-2016, 07:28 AM   #3
Dinanstu
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Change the oil pressure switch first.
Check/refresh cooling system.( thermostat, fluids, fans etc)
Is the Tray under the car still there? That affects the efficiency of cooling fan.

Worse case scenario is oil pump or crankshaft bearings are worn enough to reduce oil pressure

Last edited by Dinanstu; 05-18-2016 at 07:30 AM.
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Old 05-18-2016, 09:06 AM   #4
NSX7
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Quote:
Originally Posted by Dinanstu View Post
Change the oil pressure switch first.
Check/refresh cooling system.( thermostat, fluids, fans etc)
Is the Tray under the car still there? That affects the efficiency of cooling fan.

Worse case scenario is oil pump or crankshaft bearings are worn enough to reduce oil pressure
If the car's temp gauge stays in the middle and never overheats, could there still be an issue with cooling?
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Old 05-18-2016, 09:58 AM   #5
Dinanstu
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Probably not, just making it as efficient as possible.
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Old 05-19-2016, 09:47 AM   #6
shanehutton
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If the aftermarket gauge is using it's own sensor then you have two sensors both telling you that at idle with warm oil you have almost zero oil pressure. There is a very good chance your bearing clearances are worn and have grown. This is leading to pressure loss. Are the lifters ticking a lot as well?

You may need new bearings but as a small stop-gap you could try running a slightly heavier oil.
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Old 05-19-2016, 10:08 AM   #7
NSX7
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Quote:
Originally Posted by shanehutton View Post
If the aftermarket gauge is using it's own sensor then you have two sensors both telling you that at idle with warm oil you have almost zero oil pressure. There is a very good chance your bearing clearances are worn and have grown. This is leading to pressure loss. Are the lifters ticking a lot as well?

You may need new bearings but as a small stop-gap you could try running a slightly heavier oil.
My mechanic found out yesterday that the pressure switch is aftermarket and it is only connected to the aftermarket gauges. We will put an OE switch, cancel the gauges and see if that will solve the problem
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Old 05-19-2016, 11:03 AM   #8
Blackedout95
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It's a start, better than tearing it apart.
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Old 05-24-2016, 10:51 AM   #9
NSX7
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Just wanted to update this for anyone having a similar issue - put in an oem pressure switch (instead of the aftermarket one connected to the gauge) and cancelled the aftermarket gauge - no more oil light at idle
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Old 05-24-2016, 12:14 PM   #10
Blackedout95
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Beautiful!

congrats
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Old 07-21-2017, 08:42 AM   #11
Vcalko
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Yes!!! I've had same issue on my 2015 X5
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