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Discussion Starter · #1 ·
I have a 1989 Ramcharger with a 318 showing 217k miles, never been rebuilt.  The oil gauge sitting at a light just dropped, the oil light came on, and then it came back up, and it was fine.  No clattering or clunking in the engine.  I changed the oil pressure sensor, which now shows less oil pressure than the old one did.  Put a mechanical oil pressure gauge in, and on cold start, shows 60 pounds at idle.  Once it warms up, hot idle is 22 pounds.  I am running Valvoline Max Life 10-40 in it, and it is probably near ready for an oil change.  Any thoughts on the oil pressure readings, 22 hot at idle?
 

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Worn bearings, worn pump. Pressure is not great but adequate. You could try checking the oil pickup screen for debris - it happens often enough. If it worsens you could try replacing the pump. After that only a rebuild would help.
 

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Switching to 20W-50 will get you a higher gauge reading........but at that mileage she is in her golden years.

Bucky
 

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Mine did this too.  When a sensor goes bad it allowed oil to wick up the harness as it bleed through the inside of the sensor. It ruined the wires. I could bend the wire at the sensor and changed the readings. That said I changed to a mechanical gauge. I would consider 2 psi per 100 rpm more than adaquate. Do a wiggle test at the plug in. See what happens.
 

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60 cold , 271k MILES not clicks ? good pressure , just how cold is it there ?  lol yeah oil pump has a relief valve which may have stuck , oil pick up screen's very often get clogged with pieces of old dry hard broken up chunks of valve guide seals , but that would NOT come and go ... It's time for a pump and bearings while your there .
OR run her till she stops ...  on castrol 20/50 plain ole oil ...
 

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Discussion Starter · #6 ·
When I changed the oil sender the old one was wet with oil.  The clip that holds the plug on is broke, so I am guessing maybe the intermittent drop was due to wet/lose connection.  it has happened only twice.  About 8 years ago, I had a pan gasket leak, and I replaced the oil pump with a high volume pump.  I double checked my records, and for some reason, I didn't have 10-40 oil around, and 10-30 went in it.  With the mechanical gauge in place, at least I know what the actual reading is now.  Warmed up, at 20 pounds at idle, and 40-60 at highway I should not be hurting anything.  When I change the oil next time, I am going to do a compression test, any thoughts on what the compression should be in a 1989 318?  I have a fresh 69 HP 340 motor I am thinking about swapping in, but not sure how it will work with the EFI.
Thanks for the responses.
 

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FI with a 340 is another can of worms. You have adaquate oil pressure. If it runs well I wouldn't look much further into it.  If you were down on compression in one or more cylinders you would have drivability issues.  I wouldn't worry. The fact that you put 10w30 in 8 years ago and it sounds like it is still in there may concern me more. Oil in a bottle on the shelf I don't believe in a shelf life. After it has been in a crank case and ran is a different story.
 

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the most improtant part of compression test is how even the numbers are ... over 100 and within 20 of each other ...  your idle pressure is a tad low , and your miles are high for a set of bearings , that is normal , at lower rpm's pump makes less volume , so even when a pump is good , the leakage past higher clearences of worn bearings allow a drop in pressure , turn the pump faster , up the volume , overcome excess leakage , and the pressure goes up . The newer tall plastic senders ( not the old bell shape) often have a switch in them for the idiot light AND are a gauge sender as well , they are touchie in the gauge part , poor connections for the environment they live, made in china , junk ...
 
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