2012 Mercedes Benz C250 – Engine Top-End Rebuild
The engine in this car was originally designed for the C-Coupe from the early 2000s. That was a port-injected, supercharged affair. Now they’ve bolted on a vacuum pump to one cam, a high pressure fuel pump to the other cam, beefed up the timing chain to more than twice its original strength, made it direct-injected, and put a turbo on it.
The timing chain tensioner chronically is not up to the challenge, as in this case. Thus, that beefy, beefy chain goes out of time and valves bend.
This is not catastrophic. The head is not damaged, though it will be sent out to be hot-tanked and machined. Valves and timing chain components are replaced, and she’s good as new. However, the chain tensioner should be considered a wear item, probably best replaced every 40,000 miles.
In the meantime, we take the opportunity to clean the front subframe, steering rack, stabilizer, etc., which were grimy and unsightly. When we’re done with our work, the car should “come correct.”