Volvo 240 oil pressure light at warm idle..

I have a 1993 240 wagon with 214k miles on it, and I?ve owned it since it had 167k miles and 6 years ago. I religiously change the oil every 3k miles and use only Volvo oil filters. Today just as I entered a grocery store parking lot the oil light illuminated. Never seen that before. Got my groceries and when I came back the light was on, but then turned off as I backed out of the parking space. About 4 miles later just as I got off the highway and was at a red light the light came back on. This is less than a mile from my house and the light flickered as I drove the rest of the way home. In my driveway I noticed if rev the motor to 2500 rpm the light goes away, and as the engine settles back into idle the oil light comes back on. In May I was planning on pulling the engine to reseal it because I have a leaky rear main, and I?m hoping I don?t have to drop the pan right now. I?m picking up an oil pressure tester right using my wife?s car to check the pressure. Any ideas of what would cause the light at hot idle only? I?m really hoping it?s the switch or the wiring to it..

Could be a bad sensor but oil pressure gets lower once the engine is heated up at lower RPMs because the engine has expanded and the oil is thinner at temperature. Could be a weak pump, weak bearings, or a bad sensor.

Oil pump seals could be worn and would require pan removal. The wiring is also frequently burned up because its so close to the engine.

white855T said:

Oil pump seals could be worn and would require pan removal. The wiring is also frequently burned up because its so close to the engine.

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I am going to pull the sender and put a gauge in it. If the oil pump seals are bad, could the car be driven until first week in May where I plan on pulling the engine/trans for a complete reseal, or would I hose my engine?

The sensor closes at about 7psi which is way, way less than you need at any rpms.

Oil level correct? If low throw in some 40-50w oil or change it to 20-50w. That should get you through another month without any additional damage.

Update: I pulled the oil pressure switch and ran a mechanical oil pressure testing gauge. Car has been idling for about 15 mins and is at operating temperature and I?m seeing 25psi on the gauge. When I rev the motor at the throttle body, pressure jumps into the 60psi range. Is that alright? I?m going to let it idle a while longer and see if the pressure drops any more.

Jressman said:

Update: I pulled the oil pressure switch and ran a mechanical oil pressure testing gauge. Car has been idling for about 15 mins and is at operating temperature and I?m seeing 25psi on the gauge. When I rev the motor at the throttle body, pressure jumps into the 60psi range. Is that alright? I?m going to let it idle a while longer and see if the pressure drops any more.

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Replace the pressure sending unit.

Yes, change the sender. Sounds like you have a very healthy motor.