Don't misunderstand, Seafoam is a good product, if used for the right things. Cleaning out a nasty, goopy, gloppy, sludged up crankcase is not one of them All that does is create another problem. If it's nasty, tear it down and clean it out.

Crankshaft, camshaft & rod bearings should never not contact the journals. If or when they do, they knock. There is a "cushion" of oil between the bearing surface and the journal while the engine is running. If the oil is too thick, it can't "fit" between the bearing and the journal as easily. As a result, oil pressure increases, which is good, but oil volume decreases causing oil starvation to the bearing. Engine bearing clearances are smaller than they were years ago, as a result they need thinner oil. If you use thicker oil when the bearing clearance is good, you decrease the life of the bearings. If you use oil that's too thin, oil pressure drops and bearings end up starved for oil. If an engine starts to knock when using the correct weight oil, the damage is done. Using thicker oil might quiet it down short term, due to the thicker oil "filling the gap", but only until the next bearing is starved for oil and starts knocking. Always best to use the recommended weight oil... 5W20 in colder climate, 5W30 in warmer climate.

 

Wow thanks for the info captain. I will definitely pick up some 5w20 for the 3rd round. Since I have the top end completely torn down, what would you recommend for cleaning up the valley? Im not pulling the motor, as I have no crane and I really don't want to fight with bellhousing bolts with snow on the ground. The bottom end is pretty solid, but the top end was starting to fall apart piece by piece. I don't remember if I mentioned this, but it looks as if the previous owner may have overheated mildly one or twice. There is very minor scoring on the number 4 cylinder, and there is a newer radiator and water pump.

 

If you have an old vacuum cleaner or a shop vac, (don't use Mama's new Dyson) you can hold the nozzle next to a scraper and chisel away at it. Once you get the big chunks out, remove the oil drain plug and use solvent and a brush to finish cleaning it. Then flush it out with plenty of clean solvent, then pour clean motor oil in the valley... lots of it. The heads, (along with the intake and rocker arm covers), you can take to a self serve car wash and power wash them. Kerosene, (not gasoline) works well to clean the sludge, but keep it well ventilated. Make sure you pour plenty of clean oil in the valley to flush it out. Put her back together, cross your fingers, say a prayer, and hope for the best. Cleaning it like this reduces the risk of clogging the oil pump pick up screen any more than it already is Good luck and don't make a mess

 

A little bit of cleaning after work today Thanks for the tip with the Kero, Captain! A little elbow grease and a toothbrush got me to this point. Another round after work tomorrow. These 10+ hour days suck for trying to work on your vehicle... One thing I noticed, and have noticed on other 4.3s, is the passenger's side on the valley always seems cleaner than the driver's. Same with the lifters, rockers, and head. Is this because of the oil filler neck is on the passenger's valve cover, or is there some other reason?

 

looks good!

 

Thanks! Im going for one more round of scrubbing tomorrow in the afternoon to get the last of it out. Then time for the rebuild I wish this was over with already haha. It'll run like a champ when this is all done.

 

So you say this sudden drop in gas milege happened in about 3 week time span,with everything that you had to fix to correct the problem I say the length of time was longer than 3 weeks.Now you have the engine top half all torn apart with the sludge build up in the upper part of the engine that within it self would cause poor milege.Anyway by thetime you get dont your upper half will be almost brand new.

 

It really did happen in less than 3 weeks, and it got me worried. One thing led to another and I got frustrated. When I get frustrated, I tear things apart. When I tear things apart, I have to put them back together....Now here we are. If the gas mileage doesn't get better, my insurance rates may go up a bit

 

well its getting great mileage sitting there tore apart anyhow. work slow. dont get frustrated, get even.

 

Could it be possible that your 4wd is not disengaging? (assuming you do most of your hwy driving in 2wd).