Mercedes SLC Engine Power Loss and Noise

Whoa, that sounds rough! A whistling turning into a hiss when you put your foot down? That's not good. It's like when you're blowing up a balloon and it suddenly gets a hole – all that air escaping! I'm no expert, but could be a leak somewhere in the turbocharger system? Have you checked all the hoses and connections? Maybe something's come loose?

I appreciate the analogy. I have visually inspected the hoses, but I haven't done a pressure test. Could a minor leak really cause these symptoms, especially the stalling and increased fuel consumption? I'm trying to figure out if a hose replacement will fix it, or if the wastegate is the problem.

Okay, you've done some checking. Honestly, with all those symptoms – the stalling, the fuel economy taking a dive and the noise – it sounds like more than a loose hose. That wastegate thing you mentioned sounds plausible. My advice? Get it to a decent workshop. They'll have the right tools to diagnose the boost pressure system. Could save you headaches, and money!

Thank you for your input. A professional diagnosis was indeed warranted. The issue was a defective wastegate valve, as suspected. The repair cost 860€. The vehicle is now performing optimally. Your assistance is appreciated.