Oil Pressure Fluctuation - Cherokee XJ

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Hi, I drive a Cherokee XJ 1997 manual transmission. Over the past couple of weeks I have noticed the engine oil indicator behaving in an abnormal manner :

1. On a cold engine it shows a good oil pressure and as you increase the acceleration the oil pressure increases
2. ‎once the engine is heated to normal temperature at an RPM of approx 2k - 3k the oil indicator drops to Zero.
3. ‎when I put the car in neutral the engine oil again increases to a normal reading
4. ‎at low rpms like 1k or at rpm above 3.5k the engine oil pressure is at normal condition

Any idea if this issue is to do with only the oil pressure sensor or with any other part.

BTW I have checked the oil via the dipstick and the oil is at the normal level and the oil has been used for 4000 km.


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Downgrade to a thicker oil like 20w50 or sae40 and if it makes any difference

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If you need thicker oil to get oil pressure then there's something wrong with the engine. Probably oil pump or clearance issues in the moving parts like crankshaft bearings etc. First thing I would do would be to screw a proper mechanical pressure gauge in where the oil pressure sensor goes and get some proper readings and take it from there. Could also just be a case of crap oil. Did you change brands? Or any issues with fueling that could be causing petrol in the sump therefore thinning the oil?

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The oil grade and brand (ADNOC) has been maintained the same since the past 2 oil changes and I have been regularly changing the oil at 5000 km. After the last oil change done about 3 weeks ago, I still had the fluctuations on the oil pressure reading and with pressure indicator dropping to zero at about 2k rpm.

However, over the past 10 days I have noticed that the pressure indicator has been working fine (just like before I had this problem), and the oil pressure increases as the rpm of the engine increases which is normal behavior.


Any suggestions or ideas?

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Bum pressure gauge. Poor wiring connections.  

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