RedRadioFlyer
TYF Newbie
Long story, Ill make it as short as I can. I bought an '04 Tahoe 4x4 w/ the 5.3, 155k mi about 13mo ago - completely stock. Once I changed the oil a few times a pretty bad lifter tap appeared on cold starts, got worse pretty quickly. This gave me an excuse to rebuild the top end, and add a new cam/heads at about 172k mi. Over the 4th of July weekend I tore it down to replace the lifters w/ new LS7s, pushrods, BTR stage II cam, built 243 heads, all gaskets/hardware in between, and a dyno tune afterwards. I was a GM tech for 5 years and have done a few performance head/cam swaps on these engines in the past, so its a job I was very familiar with. Everything went pretty well until I got the front cover and valve covers off. This engine is hard sludged worse than almost any engine I've ever personally worked on. Looks like between the fuel dilution, probable long oil change intervals, an obvious overheat or two, and maybe some water entry from the previous owner, this bulletproof engine is in alot of trouble. I pushed on with the rebuild, cleaning everything as well as I could without a parts washer. Here are some pics pre-cleaning:
Note: I was not planning on replacing the oil pump or timing gear/chain at this point - I (somehow) had decent oil pressure before the rebuild and was going to do later when I had the oil pan off and/or was adding significantly more power. Oil pump was NOT disturbed so I didn't have to worry about the pickup tube falling off.
I double checked everything, put it all back together, and went for the initial engine startup. Got 0psi oil pressure after about 15sec, shut if off - crap, I guess the oil pickup tube fell off while I was manually turning the engine over or something? Whatever, time for a new pump and LS2 chain/sprocket I guess. I didn't have room to drop the diff and pan in my garage, and was short on time, so I had it towed to a shop close by. They found that the oil pan had about 1.25" of black sludge built up in the bottom of the pan, so between that and anything I may have dislodged during the job the oil pickup tube had clogged up completely - this got me worried because I know some had to get into the pump, but didn't think it would cause a massive issue. They installed the new pump, tube, and timing chain/sprocket, double checked all of my work and saw no other issues that would cause low pressure. When they started it, they only got 4psi oil pressure at idle. They cleaned out the oil pressure sensor, checked it with a mechanical gauge - still 4psi. At this point the mechanic and I assume sludge got moved through the system and probably clogged atleast one crank bearing or some other oil passage. I had him flush the hell out of it twice, once over the weekend - still 4psi on Monday morning.
So at this point, the bottom end needs a complete rebuild - something I don't have the time, tooling, or space to do myself - this is my DD. On top of that, the wife is getting very tired of my old truck habit, wants a K2xx Tahoe, and for me to stop buying NBS for DD duty. I really want to try to save it, its a great rig otherwise. What other options do I have? Anyone else here ran into anything like this? I am thinking of trying to just dump a gallon+ of B-12 Chemtool into the crank, letting it sit for a day or two, and turn it over by hand a few times. Good idea? What else would you folks do? Any help is much appreciated.
Note: I was not planning on replacing the oil pump or timing gear/chain at this point - I (somehow) had decent oil pressure before the rebuild and was going to do later when I had the oil pan off and/or was adding significantly more power. Oil pump was NOT disturbed so I didn't have to worry about the pickup tube falling off.
I double checked everything, put it all back together, and went for the initial engine startup. Got 0psi oil pressure after about 15sec, shut if off - crap, I guess the oil pickup tube fell off while I was manually turning the engine over or something? Whatever, time for a new pump and LS2 chain/sprocket I guess. I didn't have room to drop the diff and pan in my garage, and was short on time, so I had it towed to a shop close by. They found that the oil pan had about 1.25" of black sludge built up in the bottom of the pan, so between that and anything I may have dislodged during the job the oil pickup tube had clogged up completely - this got me worried because I know some had to get into the pump, but didn't think it would cause a massive issue. They installed the new pump, tube, and timing chain/sprocket, double checked all of my work and saw no other issues that would cause low pressure. When they started it, they only got 4psi oil pressure at idle. They cleaned out the oil pressure sensor, checked it with a mechanical gauge - still 4psi. At this point the mechanic and I assume sludge got moved through the system and probably clogged atleast one crank bearing or some other oil passage. I had him flush the hell out of it twice, once over the weekend - still 4psi on Monday morning.
So at this point, the bottom end needs a complete rebuild - something I don't have the time, tooling, or space to do myself - this is my DD. On top of that, the wife is getting very tired of my old truck habit, wants a K2xx Tahoe, and for me to stop buying NBS for DD duty. I really want to try to save it, its a great rig otherwise. What other options do I have? Anyone else here ran into anything like this? I am thinking of trying to just dump a gallon+ of B-12 Chemtool into the crank, letting it sit for a day or two, and turn it over by hand a few times. Good idea? What else would you folks do? Any help is much appreciated.
