Oil pressure drops as engine warms up
 

I have a 1992 with the 4.3 with 214k miles on it. I got it a few months ago and it had great oil pressure, around 60 psi with moderate throttle. Lately the oil pressure has only reached at most 40 psi when given a lot of gas. After driving around 30 miles the pressure drops even more, it gos to around 20 psi when driving and drops to 0 when idleing. I'm worried I'm going to blow my engine so I want to figure this out.

Any ideas? I'm thinking the main or rod bearings.

Honestly I donno how to diagnose.

I was gonna say pump perhaps. But there are other possibilities. Bearings are real easy to replace and cheap. I may do that for fun within the week to see how the crank is doing.


Sorry I can't help as much,

I'd try a mechanical gauge first your problem could be as simple as the old factory gauge is not reading properly wouldn't be the first time that's happened to someone. 18 years and 214k miles is a good deal of use for anything with a finite lifespan.

Sounds like my gas gauge. full to half in a second

really? maybe you'll do the next engine i need to tear apart, 'cause pulling the engine and ripping apart the bottom end isn't hard-but it sure ain't easy work either.

and i've got other things i'd like to do for fun. :icon_wink:


my first thought was like Outsydr's as well. put in a temp mechanical gauge (one that you know is good & accurate), pass the oil hose up through the rear right corner of the hood, and either hold it while you're driving or tie it to the wiper arm-just don't do that in the rain. :icon_razz: see what the mechanical gauge is telling you.

if the mechanical gauge shows all is well, then you can do 1 of 2 things. install & mount the mechanical gauge in your truck (under your dash, or buy a pillar pod) or replace the factory gauge. you can even get them rebuilt, but sometimes it's cheaper to get a new one. they also make 'Tee' fittings so you can retain the factory dash warning light.

also try adding Lucas oil additive to your next oil change, it'll help in higher mileage engines.

If you need help or suggestions on a full rebuild I can offer assistance online of course. My main experience was building up 4 bangers for boost. Other than that replacing rod bearings and such in a 4.3 doesn't seem like a big challenge. I shoudl do a build log on my truck but have just been rebuilding and refinishing the old parts because there is no reason to replace.