Engine Knocking. Bearing Replacement.

Do an oil pressure test before you do anything else to see where you stand. Report back the findings. If there was so much buildup in the engine it's not out of the realm of possibility that you have a collapsed or sticky lifter.

Now I'm NEVER the one to recommend snake oils but sometimes a bit of solvent does help to free up a lifter. Marvel Mystery Oil is a combo of mineral oil and mineral spirits and is mild enough to leave in the oil but still effective enough to do some real cleaning. I had a loud tick when cold that faded as the engine warmed up. On a whim I dumped half a bottle of MMO into the crankcase and 2 weeks of driving later, I can honestly say the noise is gone. Not faded - gone. It was gradual, but sure enough the noise faded and eventually disappeared. Even on the coldest 40F morning Florida can muster, it didn't tick. I am a huge proponent of "if you're going to fix it, fix it right" but for whatever reason this worked. Who knows - at $6/bottle it's worth a shot.

If that doesn't help and the diagnosis really is bad bearings, I think you'd be better suited pulling the whole motor and having it rebuilt. Trying to fix precision components piecemeal while the engine is still in the truck is a nightmare. You can get the bottom bearings out pretty easy, but you'll need to "spin" the top ones out one by one and that's pretty time consuming - made even worse by the fact that you'll be on your back in the cold. Furthermore it's likely that the crank itself is scored and will need to be polished. Putting in good bearings on a bad crank is a band-aid fix at best. If you're already going to do the HGs, pull the thing and do it right. It'll be SO much easier and cheaper in the long run.

Bosnian. I was totally freaking out, thinking the worst, as I normally do. I went to Wal-Mart, bought some 10W30 Max Life, some of your miracle oil, and a K&n 3001 Filter. I filled the oil filter with oil, put it on, then I put 16oz. (2 ounce per cylinder as bottle recommends) then filled it with oil. Upon starting the oil light stayed on a bit (roughly 5 seconds) I didn't turn the engine off at first because there was no sound (clacking, knocking or any ticking) the light went off and the engine idled smooth... very smooth. I let it idle for about 20 minutes then took it for a drive, no noise at all, there is a minor noise in the valve covers but I plan to do a performance cam swap with matching lifters, modified timing gear and chains, then probably buy the full gasket fit and do that. Dude, I seriously almost **** my pants when I started it and no noise... I cannot thank you enough... Next time I guess ill just have to keep my cool and not freak out.

Yeah, my oil change intervals have been less than 3000 after I did the oil pump, the lifters and stuff are just going to be replaced eventually I can slow get the carbon off of them but their probably flattened and the cam is probably well worn, Im going to buy a performance cam and matching lifters. I cleaned the bottom of the engine and timing cover extensively, oil pick up lines everything, the valve covers are the only thing left. Im also leaking oil from somewhere, so ill buy the gasket kit and replace all of them including the headgaskets, just because the truck has 130,000 on it. Its only 200$ for gasket kit with studs. 550$ for the new performance cam, matching lifters, and timing gear and chain to match. Also, would it be wise to just swap the bearings anyway? The knock is gone, but I'm sure they are worn extensively with previous neglect of motor. Its not a Band-Aid fix now, its more of a preventative maintenance thing.

I think changing the bearings out for no reason at all would be kind of shitty. Might as well pull the engine to do that kinda job. I would mic the crank bring, bring everything to the machine shop...blah, blah. Don't do it. If the bearings fail...rebuild it. I don't believe that even came close to being your problem honestly.

One thing I noticed when I first joined this forum. I had never been on another online mechanical social deal...It made me extremely paranoid. Sometimes any noise or whatever quickly became a problem from the countless threads I pillaged through here. I was trying to learn about a Vehicle I knew zero about.

The valve train setup involves the rockers being mounted to a shaft vs old v8s used to be stud mounted. The shaft is -much- quieter, but I believe from what I read and dealt with they have a tough time getting oil...add to that the cam s probably somewhat wore and this shaft the rockers mount to need to be adjusted. All the work that involves I would just change the cam, timing chain, lifters and maybe pushrods and knock out as much of it as I could at once....damn sure would throw those parts at it first before changing the main bearings... Have you ever changed them in the vehicle like that? I havent had to and I have messed up alot of cars. I wouldnt..

Talk to mike...