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Engine Building & OverhaulingAll you ever wanted to know about building and rebuilding engines in here! Remember to post your model-specific questions in the correct section.
2008 5.3 LC9 Gen4 engine build gone wrong?? Need help Let me start by saying I'm a retired bumpertobumper tech from gm dealership. Never completely tore an engine down and rebuilt it. Just partial repairs. Always wanted too, but never really had the time, place or vehicle to do it. So now i have my 2008 Avalanche daily driver that had developed dod problems and so i decided to pull the engine and tear it down and rebuild new stock parts and delete AFMDoD. I know the engine has 200k plus miles. Unknown correct miles. I purchased the
I cleaned the block and heads and measured bores determined i could just refresh with new stock parts. New Stock GM parts Pistons and Rods, Camshaft and Crankshaft. Aftermarket parts Melling valves and pushrods Michigan motorsports roller rockers, springs, retainers and keepers. Should be off to a great start! Nope! I made the mistake of watching youtube videos on resurfacing blocks and heads. This is when my head swelled up and i lost reality and bypassed the machine shop path. Never in all my 20 years ever did anything like bypass machine shop. Ugg. I put together a 3/4 15x30 board and routered out 1/8 in hole to fit a 12x24 porcelain tile from lowes. I put the straight edge on it to verify flatness. I have a machinest straightedge. Glued the tile in the slot and glued 240 grit sandpaper to the tile no overlapping of sandpaper. A week later me and a friend put each head on the sandpaper tile and pulled back and forth from each side making sure we didn't push down and only pull. The heads were looking beautiful. We stopped on the heads and put the block on it. Same procedure. I noticed low spots or areas that were not getting clean. So i grabbed the straight edge and found the heads and block has low spots. I then checked the tile for flatness and it had developed a high spot. O know! I’m not sure how it developed this but i stopped everything and took the block and heads to the machine shop. The machine shop said they dont recommend decking the block because they have no way of telling where the specs are at. I was like what, wait Who! O no learning curve ball. What does this mean??? They recommend resurfacing the block and heads just enough to get them flat and using thicker head gaskets. And bore and hone. And rebuild the heads. And getting oversized pistons with rings. Said the stock rods are fine not to waste money on them. so I was able to return the GM stock pistons and rods. But now after looking up going to far on heads and or blocks can cause all kinds of problems. Great now what do i do?! I don’t think the block or heads have ever been touched before me. You can see the numbers still, so doesn't that mean it wasn't decked? Sorry for the long story but wanted to give as much info i can. So is this project botched beyond proper repair and buy another engine? No funds for that now. How will I know the head gaskets are the correct size and will work? Cant the machine shop know if it’s in spec heights after resurfacing. This has gone out of my experience and I’m lost. What a bummer! How do i get this project back on course?
Only have pics before the sanding. Everything is at machine shop now. Before cleaning After cleaning and before sanding
March 14th, 2024, 12:48 PM
Gen 4 rebuild gone wrong, maybe?
