hi all! I recently purchased a 98 Cherokee, and the oil pressure was showing low at idle (about 5) so I changed my oil. It brought the pressure up to about 10 at idle.

the quirk I am having, is that sometimes when I start the jeep, it reads 0 fuel pressure at idle until I rev the engine. This is only occasional. Otherwise it's reading about 5. After revving the engine up, it sits at 5 at idle. Any ideas?

the oil that was in it before was some of the oldest oil I've ever seen, and I replaced it with 10w30. 154k on the jeep, runs like a champ, pulls very well.

i am considering running sea foam through the tank, and switching to 10w40, but im not sure it will help

 

You might just need to replace the oil pressure sensor.

 

First , you need to find out if that reading is accurate. If you can get a mechanical gauge on it you can find out the true pressure. I had a similar issue on an older jeep and installing a new sending unit was all that was needed.

 

I cringe when I read that you rev'd an engine with zero/low oil pressure. Is the engine noisy (ie: knocking, lifter clatter) when it shows no/low pressure? If yes, you have a problem worse than dirty oil. If no, I wonder if the pressure reading is any where near accurate? To verify actual pressure you can install a direct reading oil pressure gauge between the engine & the sending unit. (There are inexpensive test kits for this.) This way you will know the actual pressure. The second part of the issue is the internal 'cleanliness' of the engine. After a lot of busted knuckles (and working a while for one of the major oil companies test lab - long time ago), I am not a big fan of 'mechanic in a can'. I think you would be better off using a good quality oil & good filters and do a couple of short interval oil changes (2000-3000 miles). If you still have the old filter you can cut it open & check between the pleats for metal. If you find metal in the pleats, start looking for money for internal engine work. If no, than there is hope. I am sure there are lots of opinions as to which oil, which weight, what type is best. There are lots of threads, and even websites dedicated to the subject, but know this: you need flow, not high pressure to keep the engine going. The engine needs oil with sufficient shear resistance to keep the rotating parts apart, flowing in large enough quantities to carry away the debris & heat, and with enough of the correct additives to keep it working thru a wide range of operating temps & conditions. It needs to be clean. Use quality filters, & good oil (sometimes synthetics seem best suited) of the proper weight & API rating. Let your engine warm up in the cold, and don't overheat it (winter or summer).

 

Yep. You can get a Bosch for under 20 bucks at Pep Boys. It will take you maybe 5 minutes to remove your sender, plumb the Bosch connector in its place, and set the Bosch up on your cowl where you can read it from the driver's seat, fire up the engine and know what your oil pressure really is.



Yep. What he said.