I have a 2001 Ram Sport 1500 5.9. My oil pressure sits around 35 psi at idle and around 45-50 psi while driving. Lately, when coming to a complete stop, my oil pressure gauge will drop to 0 psi for about 1 second and then immediately read correctly again. It's so fast that when it first started happening I would only hear the chime and the problem would be gone before looking down at the cluster just to see nothing wrong. I had to really look for the quick drop to 0 psi and then the immediate climb back to 35 psi at idle again. It never happens while driving, just when reaching a final stop.

There are no knocking or ticking sounds, engine runs great, and no oil leaks. I did replace the oil pressure switch about 2 years ago... not for an oil pressure issue but because I accidently cracked the plastic housing while replacing the distributor cap (don't ask). Lol.

What could be causing this problem? A bad pressure sensor, sending unit, pump? I searched the forum but found nothing that matches my problem, so any help is appreciated. Thanks.

 

Bad sending unit or Plenum gasket is blown

 

Sounds like its low on oil. As you are stopping the oil doesn't flow to the back of the pan, as soon as you are stopped it can and it hits the pickup tube again.

 

Hey, thanks for the quick reply. How would I tell if the plenum gasket is blown? I don't seem to have a vacuum leak... the engine idles great, cruise control works, CAD works and holds, no hissing air leak sounds, etc... I did do the plenum plate upgrade a few years ago as well. What else should I look for when trying to identify/isolate a blown plenum gasket? Also, how would a blown plenum gasket cause a momentary drop of oil pressure indication? Thanks again for your help.

 

I checked all my fluids a couple weeks ago (I usually do this every 2 weekends as its an older truck) and oil level looked good... but I'll definitely check it again today. Thanks.

 

Also, how do I verify that the sending unit is bad? Would I have to drop the pan or put a pressure guage somewhere? Thanks man, looking forward to hearing back.

 

If you already did the Plenum plate most likely not that. Mine did the exact thing when it's blown. Get a pressure gauge screw it into where the sending unit goes. Take it to the windshield and take a drive. If it doesn't drop on the mechanical gauge then it's the sending unit . No problem man

 

That's thinking outside the box, I dig it!

 

Just standard procedure so can't take the credit! Lol

 

You nailed it.... I was about a quart low. I'd been checking my fluids in my driveway... its a pretty steep driveway which makes for a full dipstick even if oil level is low... I'm a damn dipstick myself for not catching this.

Thanks for the help man. And thanks for everyone else who offered suggestions as well. This forum is awesome.