need advice low oil pressure 350 tbi

Hey guys,
I need some advice. I bought a 95 Z-71 off craigslist. It had 220k well documented miles. Two-owner truck, uncle gives kid his truck, 6 months later kid gets truck stuck in mud up to the doors. I bought the truck knowing the engine was shot. It knocked hard in the bottom end. I assume he sucked water into the engine and spun a couple main or rod bearings.

I just swapped a known good engine into this truck. It started on the first try, perfect, 60psi cold oil pressure. I took it around the block, and a lifter started ticking, oil pressure around 30-40psi. New AC Delco filter, and valvoline 10w-30. Ticking gets worse, oil pressure dropped to around 5-10 psi warmed up. warning light coming on at idle.

I flushed the engine with STP engine flush per instructions. I started to hear more lifters ticking. I assumed this was good, now I know its lifters and it seemed to be doing its job. Drained old oil, filled up with Valvoline 10w-30 and a half quart of marvel mystery oil. Ticking went away in 30-60 seconds of running. Took it around the block, did OK. Now it ticks on and off worse when its warm.

Im trying to trade this truck to a buddy for a rig he has. He helped me with the swap, and now he's getting cold feet (I don't blame him) What should I do next to try and solve this problem?

I read using 20w-50 and lucas oil stabiliser. Will this do the trick? any help/experience would be great...

I think 10w-30 oil is way too thin for an old style 350, I wouldnt use anyhting thinner than 15w-40 or 20w-50. Other than that, pull the engine again and plastiguage the rod bearings, and if they are way out of spec, try putting a new one in and see if that helps.

Drain oil save it, remove oil filter and screw on an oil filter remote adapter. use compressed air to blow in both hole on the adapter slowly turn motor over while blowing in the adapter. this will blow out any crud in the lifters and also blow back the pump and screen. More then likely you have plastic chunks from the timing gear that float over to the pick up and starve the pump. you can do this with out the adapter but you get better seal with it. use max psi to back flush. you might find a bunch of tin foil quart tops

how long did the engine that you put in the truck sit before it was installled?

crap in the pickup screen?

Travis_K wrote: I think 10w-30 oil is way too thin for an old style 350, I wouldnt use anyhting thinner than 15w-40 or 20w-50. Other than that, pull the engine again and plastiguage the rod bearings, and if they are way out of spec, try putting a new one in and see if that helps.

I've run 10W30 in every 350/305/400 I've ever owned and they all ran fine. That's crazy talk.

hotrodlarry wrote: how long did the engine that you put in the truck sit before it was installled?

hmmm, about 6-9 months. All but 2 weeks was in the truck, 2 weeks in the back yard. Interesting...and I started the engine with the oil that was in it. The oil was less than a year old, with maybe 1000 miles since new. I planned on drivin it for a couple days before doin an oil change. Just to get everything movin around.

might have bit me in the ass huh?

dwarf's suggestion seems right on. or just drop the pan and look at the pickup.

Where did the engine sit? Check the oil to check for a milkshake. Engines are like cars - "ran when parked" doesn't cut it all of the way to "known good".