louisklein44

Mercedes R Klasse Diesel Turbo Issue

I'm having trouble with my 2012 Mercedes R Klasse diesel. It has 109143 km on it. Performance is down, the check engine light is on, and the engine response is poor. I hear whistling that turns into hissing when I accelerate. Sometimes the engine stalls, and fuel consumption is up. I think it might be the boost pressure actuator valve, maybe an electrical bypass issue causing a boost leak in the turbo system. Has anyone else seen this?

4 comment(s)

I had similar symptoms on my old Vauxhall Astra diesel. It was a split hose on the turbo. Check all the hoses for cracks and that the actuator arm is moving freely. Did you check the turbo actuator?

Thanks. I'm going to check the hoses. When you say the actuator arm's range of motion, what should I be looking for? Is there a specific range of movement I should expect?

On my Astra, the arm was seized, barely moving. I couldn't see it without getting under the car. If yours is moving freely, it's probably not the turbo actuator itself, but a boost leak somewhere. If it's seized, you need a new turbo or to get it refurbished. I'd suggest a workshop visit at this point.

Thanks for your help. Your Astra experience was spot on. It was the boost pressure actuator valve. The electrical bypass had failed. Replacing it cost 250€. The car is running great now.

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