I have a 1998 Jeep Wrangler Sport, 4.0 motor, 175,236 miles, manual transmission. after i drive for about 20 minutes i notice my oil pressure gauge will drop when i stop or am at idle but will go back to normal when i start to drive again. should i be concerned?
It's normal. I'd be concerned if it didn't move. 23yrs old jeep, surprised it still working.
Those 4.0 inline engines are a completely different world from the crap that Fiat has been selling. The 4.0 with even cursory maintenance can easily run for decades and hundreds of thousands of miles without major repairs. The old Jeeps have their problems to be sure (built by AMC then Chrysler) but there is no comparison with today's rolling piles of junk.
Oil pressure of course will vary with engine speed and will be lower at engine operating temperature than when cold. How far down does it drop? Factory spec when the engine is hot is a minimum of 13 psi at idle, and 37-75 psi over 1600 rpm.
Also, the oil pressure sensors on those are notorious for being inaccurate. A diagnosis of low oil pressure should be confirmed with a mechanical gauge. Another issue is that the passage that feeds the oil pressure sensor can plug up especially if the oil is not changed regularly.
it stays at 40 most of the time but will go to id say 15
You're within factory specifications then and I wouldn't worry about it. Just change the oil regularly and that thing should run just about forever. Keep coolant clean as well. The core plugs in that engine are a real PITA to replace, especially the ones in the rear.
thanks!
What's the pressure?
40 most of the time but goes to 15
Seems to be normal based on @Chuck Tobias.
thanks! it still runs great
Sounds normal for an old vehicle. If you want higher oil pressure, use a heavier weight oil, ie, 10w40 instead of 5w30. Or just add a bottle of STP Oil treatment.
