Valves are popping on acceleration, especially up hill. Could it be bad gas or something else?

Asked by Jan 22, 2015 at 03:38 PM about the 1999 Mercedes-Benz C-Class C 230 Supercharged Sedan

Question type: Maintenance & Repair

Clicking sound, valves. Usually on a hill, trying to accelerate. A little cough and backfire as well. Could it be crud in the gas tank? I have been running with high octane fuel, but bouught from a low volume station just before this began to occur.
C 230 Kompressor

1 Answer


How many miles on the drivetrain? As to it being "crud in the gas tank," no, your fuel filter would prevent that (and if the fuel filter was bad, you would have a loss of fuel pressure). You might have worn valves/valve guides/valve seats, and a corresponding loss of compression. A compression test on each cylinder will help you determine that.

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