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Buick LeSabre Oil pressure loss when car heats up.

breebreebreebree Posts: 2
edited May 22 in Buick

2002 Buick Lesabre Custom 3800 series 2, thermostat opens at 195. Digital temp is 222, electric fans do not turn on. Fan motor hot, relay is warm(even switched relays),fan comes on at 224. Oil pressure goes to zero when car heats up. Where do I start to fix this?

Answers

  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,197
    edited May 22

    Not enough information. How many miles on the car? Frequent and regular oil changes? When was thermostat changed last? Was coolant changed every 3 years or less?

    What relays are you talking about?

    The oil pressure sender can go bad. On some vehicles it pegs at maximum pressure indicated on the DIC even though the pressure is normal, 40-60. Replace with AC Delco brand. Can be do-it-yourself project by removing right wheel and oil filter to get to the switch.

    Do the engine cooling fans come on when the AC is selected and the outside temp is above 50? Is the digital temperature 222 with car moving at 40-50 mph? Or is this idling?

    Because the coolant temp runs up before the cooling fans kick in if the AC is not already on, I often turn AC on with lower internal blower speed to make the engine cooling fans run. They will switch to high speed at about 217 and cool things back down fast and then revert to low speed.

  • breebreebreebree Posts: 2
    edited May 23

    Electrical relay for cool fan under hood in fuse box..The car has 260,000. Just bought the car 6 months ago. No thermostat in it, looks like it was taken out. 222 at an idle. We have changed the oil in it since getting it.

  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,883

    If your oil pressure was actually zero, the engine would knock like crazy. I would insert an actual oil pressure gauge into the motor and first get an accurate reading of what actual PSI is. You could have unrelated problems going on here.

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  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,197

    @breebree said: Electrical relay for cool fan under hood in fuse box..The car has 260,000. Just bought the car 6 months ago. No thermostat in it, looks like it was taken out. 222 at an idle. We have changed the oil in it since getting it.

    Now that I hear 260K mi, where does the oil pressure start when the engine is cold? It would have been 60 new, and 40 with couple hundred on it.

    As Mr Shift clearly said, you need to know what the real oil pressure is doing. Lots of clearance in the rod/main bearings will drop the pressure, especially if the engine has had some bouts with leaking coolant in the EGR passage inside the Upper Intake Manifold or the lower intake gaskets against the heads. The coolant deteriorates the bearings when left in the oil. What does the oil look like that you drained out? Chocolate milkshake colored due to coolant mixed? Or clear with lots of dark dirt particles?

    Is the coolant level dropping in the radiator or reservoir.

    You need the thermostat in place. These thermostat sits in a slit in the rubber large o-ring that seals the thermostat housing to the intake manifold.

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