You need to take the head off and replace at least the intake valves that are bent. Your timing chain jumped a tooth and had it been correctly diagnosed at the beginning it would have saved you a lot of money. M271 engines are notorious for they're timing chain problems. Here is what you need: timing chain, all the chain sprockets (they wear down), timing chain tensioner, all the valves that are bent, new head gasket, new valve gasket, thick wallet and a new car (with something else than an M271)

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600SEL '91
300E 4Matic '88
240D '83
280SE '77
350SE '73
The most complex systems can fail in the simplest way.
Contra verbosus noli contendere verbis, sermo datur cunctis, animi sapientia paucis.

i don't believe in the lord! He's never bought me a Mercedes Benz.