I just pulled one of the stupidest stunts I've ever done. I changed the oil in my beautiful 1982 Mercedes 300TD wagon. Forgot to put the gasket on the oil filter cover. I drove it while, unknowingly, it blew oil in the engine compartment.

At some point, the engine began to tap really badly (sounded like a bad valve or valves).

I turned it off immediately. Replaced the gasket. Re-filled oil, but too late. The tapping was still there. Engine wobbles intermittently but badly.

I'm guessing that it's a bad valve (or valves). If someone had to take a totally wild-ass guess, how much would you think it would my mechanic would charge to fix this engine?

I'm guessing the total cost would be between 2k and 3k. Does that sound about right? If it winds up being an engine replacement, how much does that cost?

Just trying to get a sense of how bad I should beat myself over the head (which I obviously have no need for).