Why does my 98 jeep cherokee lose oil pressure when I come to a stop?

Question

When I'm driving, the oil pressure goes back to normal. When I slow down and stop, it dips REALLY low. I can't seem to figure it out. Obviously I'm concerned about engine damage but don't have to dough to take it to a shop just yet.

When I'm driving, the oil pressure goes back to normal. When I slow down and stop, it dips REALLY low. I can't seem to figure it out. Obviously I'm concerned about engine damage but don't have to dough to take it to a shop just yet.
UPDATE - The car has abou125K miles on it and it seems to run fine other than the oil pressure. I've noticed that when it's 100+ degrees outside, the engine temp does climb slightly above normal in the city I'm assuming due to the low pressure when stopped. Currently using 10W30 oil.

Answer 1

two possiblities here, 1). you could have a oil pump going bad.
2.) you could have rod and main bearings wore out of clearence.
Either the oil pump can't produce enough pressure at lower RPM's or the bearings are loosing the pressure. Either way, I would drop the Oil pan and replace both, probably time for it anyways!

Answer 2

I noticed that no one said that it could be your oil pressure regulator. It uses a spring and a piston that adjusts to the RPM of the engine, if the piston gets stuck or the spring is broke, it would cause the pressure to drop off as you suggested, as well as the bearing ware that michael081278 suggested.

You can put 20W 50 motor oil in and see if the pressure comes up at idle, if not I would check the pressure regulator next then the oil pump before replacing main, rod and cam shaft bearings.

Answer 3

You have received a good bit of good advice here as to the various possible problems--some as simple to fix as the pressure regulator, and others more complex and expensive, like new crank shaft bearings, although there is even a quick and dirty way to replace those without committing to an engine rebuild.

However, if you have even as much as 15 pounds of pressure at idle, it is probably sufficient, so long as it does climb significantly when your RPMs rise. I should hope to see something around 60-75 pounds at highway speeds.

Answer 4

How many miles on it? If you have high miles, consider a step up in viscosity. If you're using 5W30, go to 10W30. Keep up on your oil changes, 3mo/3000mi. Try a good engine treatment like Lucas or Slick50.

If that doesn't help, change the pump.

Answer 5

IT MAY BE TRUE THAT IT IS TIME FOR YOU TO REBUILD YOU ENGINE, HOWEVER, I HAD AN OLD TRUCK WITH THE SAME PROBLEM AND DONE SOME CHECKING, I WAS TOLD THAT IF I HAD AS MUCH AS 12LBS OF PRESSURE THAT IT WAS OK, JUST WATCH OUT FOR OVER HEATING. I DROVE FOR ANOTHER YEAR BEFORE I REBUILT MY ENGINE, WHICH I DO BELIEVE IS WHERE YOU ARE HEADED SOME WHERE DOWN THE ROAD.

Answer 6

try replacing the oil pressure sending unit