humming sound from engine on cold start up
01-13-2003, 06:55 PM
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2004 Audi S4, 2003 CLK 500
humming sound from engine on cold start up
I have noticed in the past week when I start up the engine after it has been sitting in the cold all night, there is a humming sound coming from the engine when it is idling. It seems to disappear once I start driving. I am not referring to the ticking sounds that some people have complained about. Any thoughts.
01-13-2003, 11:06 PM
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Mercedes C240X
Rocky,
The humming sound is perfectly normal for the engine when it is first started in cold. I have a C 240, and the engine sound just exactly like you have described. The humming sound is actually the air pump that pumps air into the engine during cold start for emission purposes. Very innovative of MB to design such feature, but at the same time, it just adds too much complexity.
My car engine continue to make the humming noise until the engine temperature reaches normal. I am not too sure about yours?
mrfu
2001 C240X / Desert Silver / Java (57,000 km with more than $10k in warranty repairs)
The humming sound is perfectly normal for the engine when it is first started in cold. I have a C 240, and the engine sound just exactly like you have described. The humming sound is actually the air pump that pumps air into the engine during cold start for emission purposes. Very innovative of MB to design such feature, but at the same time, it just adds too much complexity.
My car engine continue to make the humming noise until the engine temperature reaches normal. I am not too sure about yours?
mrfu
2001 C240X / Desert Silver / Java (57,000 km with more than $10k in warranty repairs)
