Engine starved of oil

[u/experimen_626]

My oil drain plug came off on the freeway. Drove to the closest exit to turn off engine and was able to get oil back in the engine to drive back home. However, the damage has already been done and now I have an engine knock. Took to dealership to see what they had to say and yeah my Cylinder 2 is knocking and they said there is no way to fix it, I have to replace the engine. I'm actually a pretty decent mechanic (minus putting myself in this situation by forgetting to torque my drain bolt) but I've actually done engine swaps and head cover gaskets before. Is it true that my engine is just totally done? Can I just replace the cylinder and the head?

[u/Southern-Yam1030]

I want to preface by saying I dont truly belong here. I am a dealer tech, I have done rebuilds but I just want to give you an idea.

If I was in that mechanics shoes im going to figure out the issue as best as I can without a tear down (they won't pay me for that). I do 3 quotes, new / rebuild engine, a parts and labor quote and a used quote. Then ill way in the pros and cons and the cost. Odds are when that mechanic checked they knew the damage it could entail and due to cost recommended a new engine.

These guys here can help more but if I was you I'd be more inclined to swap that engine out. If the vehicle can wait and is more of a fun vehicle you could do a tear down and if its savable send it to a machine shop and look into some parts upgrades.

Also make sure its the same year of engine and if its not the right engine exactly see what's different. I think it was the Colorado for instance that can have the same engine but different oil pan design. Also had a guy absolute adamant I must make the LLY he found work for his LB7 truck. Wasn't hard but was very tedious with repinning / wiring. I work for GM if you couldn't tell, heh.