Oil Pressure

BoogieShoesMike

My car has 102,000 miles. It has the 4.0 V-8 North Star motor. I checked the oil and it was down a little over a quart. I added a quart of Valvoline High Mileage 10w-40, this is the same oil and weight I have always used. When I drove the car, my oil pressure started to randomly read zero, then shoot up to 125lbs and then be fine for awhile. The readout would repeat this over and over again. It's still doing this, it has been going on for about 2 weeks now. I have never had this experience before and I am 70 years old. I have owned, now 5 Auroras since 1994. My first one had over 300,000 miles on it when I bought my second one, never have I had this experience with any of them. My mechanic can't explain it either.
Any ideas..............?

imidazol97

I'd suggest replacing the oil pressure sender/switch.
Rockauto.com
It's in the electrical-switch and relay category of parts under Oldsmobile 1999 aurora.
About $30

I had the sender go back on my 3800 leSabre. I believe mine just went to a high pressure and stayed there...

It may be easy to get to. If you'r got a mechanic, it's a piece of cake.You might try removing and replacing the connector and check the wiring on it for breaks. But the idea it's going to 0 or 125 suggests it's not a break. That would alternate between a normal reading and one of the extreme readings.

Good luck.

BoogieShoesMike

Thanks for the suggestion, the other weird thing is that before I added the oil. I didn't have this problem! My oil pressure is in the form of numerical readout on the systems monitoring panel, not a manual gauge.

imidazol97

I understood that. The readout on my leSabre 03 was digital.

If the engine does not make noises from the lifters having too much play because of no oil pressure pumping them up when the gauge reads "0", you most likely still have oil pressure.

I can't recall if my leSabre went high or low on the reading. But I have read enough reports on car forums about the H-bodies that I knew what it was likely to be.

Mine just gave a bad reading when I started it up after being at some store. Sender just decided it was time to not cooperate.

BoogieShoesMike

Thanks for the suggestion, the other weird thing is that before I added the oil. I didn't have this problem! My oil pressure is in the form of numerical readout on the systems monitoring panel, not a manual gauge.

BoogieShoesMike

We replaced the Oil Pressure switch/sensor now the problem is worse than ever. It appears as though the oil pressure is fine in spite of near zero or zero readings, the car runs fine. Just aggravating with the zero reading and the alarm ringing plus the check engine light coming on and preventing the car from passing smog. I really need some help in solving this problem.

imidazol97

I assume the mechanic attached a gauge to the engine and drove it to verify that the oil pressure is not going in and out due to a pump problem or a pressure control valve problem.

All I could think would be to follow the connections from the car's sensor to the module where the input is converted to digital form. I's suspect fretting on the connections. Open each one, visually look at the connectors for corrosion, maybe put on dielectric grease and reseat.

Could be an internal problem in the module that handles the voltage input from the sensor. I have no idea which one it might be.

To fix this might require a Tech II computer connected which _might_ be able to determine the module is giving you the wrong synthesis value for pressure from the analog input it gets. It would be something like how some body control modules go wrong and just have to be replaced.