So last year I bought this 89 with a 2.5 and an np2500 manual trans. I've been working on it on and off and finally got it to run decent but I noticed when it gets to operating temp it loses all oil pressure, so I bit the bullet and installed a new oil pump and pickup tube. After a few more weeks of tinkering on it again I drove it a bit and it's exactly the same as before, loses oil pressure at operating temp, I do actually have a mechanical gage in the truck so i can see it has 10-20 pounds until operating temp then it hits zero, so it has me wondering if I should give up on this motor. I just need some advice as to if anyone knows a solution to this or if I should try and find another motor to put in it. If I do put another motor in unless someone in Arkansas is selling a 2.5 tbi I'll have to go another direction cause I haven't been able to find ANY of them in local junkyards or on Facebook. Any input would be lovely.

Also, I do know my father has a 95 dakota with a 318 in it that hes planning to give me as a parts truck for mine, but its a 4x4 automatic with the extra cab(whatever its called on these trucks), but i could potentially yank the motor and rear-end out of it for my truck. Thank you for your time.

 

Assuming you are going by the gauge on the dash, try replacing the oil pressure sender. It's real cheap on RA. Mine looked like the oil pressure was dropping out and it was the sender unit.

 

I should have mentioned, I'll edit it on the post. I actually have a mechanical oil, temp, and volt Guage set in the truck