in December I bought a 2001 Grand Cherokee 159,000 miles 4.0 and it's a really clean vehicle, runs great - no clicking/ticking/knocking and I would like to keep it - but ..... after warming up the oil pressure is dropping to near 5lbs. Having had a 98 Cherokee that had the same issue I changed out the pressure sending unit with a Mopar oem and serviced the engine and bumped up to straight 30 weight oil. No improvement this time - darn ..... Next step I ordered a stock pressure Melling pump and pickup. Dropped the pan today and immediately realized someone else has been in there and they had replaced the stock oil pump with a Melling high volume pump and a new pickup. They were both crisp new looking and clean/no debris/clogging. .... So ....... I now this isn't as simple as an old oem pump needing replaced. Need some advice on what I'm seeing as my options ..... 1) Button it back up with the high volume pump and keep tinkering with heavier oils. 2) Button it back up with the new stock pressure pump and again tinker with different oil weights. 3) Roll in (in the chassis) new bearings and button back up with either the high volume or stock oil pump. 4) Pull the engine and do a rebuild. 5) Salvage yard engine swap. 6) re-manufactured engine from someone like Jasper.
I'm open to any and all suggestions please. Give me something to think about. I've roller in bearings before on a Wrangler and it ran fantastic and was dependable, later selling it. But that isn't always the case going that route. A salvage yard engine is always a risk - period. .... Suggestions?

 

A lot of people drive them like that for years. If you decide to take action, consider crossing a reman (option 6) off your list. Here's why.

Rebuilding yourself is not difficult.

 

Button it back up and use Rotella T6 5w-40 oil which should raise the pressure to something you can live with while you buy a good used motor to rebuild when you have time. As long as the rest of the body and drivetrain is in good condition, it'll be worth your time. The major problem with an in-chassis rebuild is you'll still have worn cam bearings. Just my opinion however.