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What can this issue be?

(2004 Mercedes-Benz C240 4MATIC)
in Charlotte, NC on March 06, 2013
At first It started with clicking noise from vents when heater or air was turned on. Now all of a sudden without warning a loud knocking from under the hood.
Displaying 1 answers & 0 comments
Popular Answer
on March 06, 2013
check your fluids. if you have low coolant or oil that could be your engine knocking.
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