1999 Jeep Grand Cherokee Repair Question
Mileage: 160,000 miles.
Why does my oil pressure drop when I come to a stop and then go back to normal when I drive off?
Asked by Steven W. CannedyAnswer
Because the oil pump is engine driven. As the engine speed goes down, the oil pump output pressure decreases. The oil pressure should not drop below about 20PSI. You should hook up a dependable oil pressure gauge and see what pressure is developed at idle.
SUMPIN' LIKE MINE
EVEN ONE OF THOSE UNDER DASH UNITS WILL WORK FOR TESTING, MOUNT IT PERMANENTLY LATER, OR KEEP USING IT AS A TESTER
A MECHANICAL GAUGE WILL GIVE YOU A TRUER READING, AS COMPARED W/ AN ELECTRIC GAUGE
IF THE MECHANICAL GAUGE IS TELLIN' YOU EVERYTHING IS A-OK, AT ALL RPMS
THEN YOUR OIL SENDING UNIT ON THE ENGINE IS PROBABLY (MOST LIKELY) THE PROBLEM----BUT NOT COMPLETELY RULING OUT A GAUGE PROBLEM (SELDOM)
KEEP US INFORMED
THE MEDIC
That is just normal pressure changes that happens in all vehicles as long as it is not dropping low enough to put the warning light on.
It is dropping to almost zero, Wrenchtech. A bit too far.
The right way to check it would be with a manual gauge but the price of a new sender may make it cheaper to just trying a new sender instead.
Eh, I don't like most stock gauges. I prefer a decent mechanical gauge from Sun-Pro. Borg-Warner or Autometer would be the best.
Come on, you're stuck in the 60's.....LOL
Nope. Unless they're on something like a performance vehicle,stock gauges are usually unreliable.
That hasn't been my experience. Maybe on a racing engine.
WHEN YOU ARE "AS ONE", WITH YOUR "REAL" VEHICLE
ONE CAN SENSE AN ABNORMALITY
AND NEVER EVEN LOOK AT THE GAUGES!
THE MEDIC
