BowtieFly

Hi All!! First time poster.

I have a van that has me scratching my head and questioning my skills
The van is a 2006 Express G2500 with a 4.8L engine with 90,737 miles. The current issues is oil pressure. Now this isn't my first van I've had employees run into the ground so I know what that normally means, but in this case it doesn’t show the other obvious signs of issue.

I will apologize up front for the length of the kick off post here. The story here goes back about a year, usage has been spotty as I've had time to try this and try that and then drive for a little while.

Added note - after typing my --- off this is crazy long, I'll post a summery in a second post

About a year ago the van started sputtering at lights and struggled to get going. you'd pump on the gas a little bit and it went back to running great. At first it was once in a while then it was a few times a week... you see where this is going. Anyway all gauges looked fine, I checked fuel pressures, replaced plugs, wires, suspicious coil pack. It seemed to get better so I turned it over to an employee to drive. He had it for 3-6 weeks and I didn't know at the time it got worse until he picked me up one day and the thing was choking and knocking so bad it wouldn't even get up to speed and oil pressure gauge went from 40driving/30idle to less than 10driving/under 5idle. As well the check engine light was on full time now.

I started this hot mess at the trans shop since I could hear engine rev, although barley and really rough. But van not getting up to speed. turns out issue #1 is broken flywheel. had that replaced but still barley running. since it was winter at this point I had a local shop take a look as it wouldn't hardly run at all now. they told me it was one of the left Cats plugging up and the two oxy sensors were shot. they wanted a fortune to fix it because the bolt in OEM cats pipe is $700 and the other option is to go after market and spend the labor welding and retrofitting.

I brought it home, ordered aftermarket sensors and a cat. Pulled the pipe off and the left was fine. since I was under the thing I pulled the right off and the upper right cat had broken apart and clogged the lower one. I gutted them both welded in the aftermarket cat if it worked I planned to put OEM part in later in the year.

Started it up and BAM running great, but low oil pressure. So I take it in and get change the oil and filter changed and drive it while keeping an eye on it and it never gets better or worse. maybe 500 to 1000 miles. When I had oil changed they said it might need a flush (standard quick lube up-sale) so I said no at the time. Still no change I also had heard that sometimes when cats go bad the crap in the oil will plug the pick-up screen and/or crud up the oil pressure sensor. I tried replacing the sensor - no good. I took it back to the local shop and asked them to pull the pan and check the pick-up.

The first thing they reported was the oils was a couple quarts loAw. this surprised me, less than 1000 miles since change, no leaks under van, never did this before. so they topped it off and hooked up a mechanical gauge which confirmed the same thing as the sensor 10/under 5. They then drained the oil ran a scope into the oil pan and looked at the pickup screen and reported it looked good. They re-filled the van with heavy oil (I think 20-50). At first it seemed like the pressure was a little better, but within 10 or 15 miles it was exactly the same as it was going in there. They felt like it must be warn bearings.

At this point I’m not sure what to do so I get the engine flush crap, I dump it in and flush the engine oil as the directions say to do. I change oil and filter this time with normal oil weight (5-30 I think) and it’s a little better but again after 10 or 15 miles right back to where I started. So now what??? Last ditch effort, get out the Lucas!! Added it, no change.. Seriously no change from adding the Lucas.

Is there anything else I can do before just getting a new motor and replacing the whole thing? Can the bearings really go from good to bad in 4K or 5K miles? If it’s flat out bad bearings shouldn’t I see a change from adding the Lucas? Plus where did they couple quarts go in 500 to 1000 miles? It’s not smoking, this not leaking. The engine bay is not all grimy.

As I said I’m left scratching my head and at a loss for what to do next.

Thanks,
Doug

BowtieFly

Here is a the highlight reel, much quicker to read.

85,000 miles - cutting out here at there, pumpig gas and away it goes. Oil pressure good

86,000 miles - changed plugs, wires, one coil pack. seems better give to employee to drive. Oil pressure good, seems fine.

90,000 miles - rattling, cutting out, check engine light on, oil pressure bad. Changed flywheel (the rattle) with new, replaced right cats pipe with one aftermarket welded into pipe, replaced oxy sensors. changed oil and filter. everything is great now, except oil pressure still very low.

90,700 miles - missing about 2 quarts oill, oil pressure low. Change oil pressure sensor, verify very low with mechanical gauge. scoped oil pan to view pick-up, reported as fine and clean (someone else not me persoanlly). changed oil to 20-50 weight. slight change for 10 to 15 miles, then same as before

90,720 miles - Flush engine oil, replace oil and filter, normal 5-30 weight. Slight change for 10 to 15 miles, then same as before.

90,730 miles - Add 1 quart Lucas oil stabilizer - no notable change.

What do I do next? What else could be wrong?