I recently bought a Ford C-Max 05, and have found that when I am stopped in traffic a strong smell of petrol or oil comes through the air vents and there is white smoke coming from the bonnet. Does anyone have any suggestions on what this could be?

  • 1
    Has this just started or did you buy this with the problem? If you bought it from a dealer take it back, right away!
    – GdD
    Apr 19, 2018 at 13:09
  • I’ve had the car week and I noticed it quite early on after the sale, however it was a private sale and im getting no reply Apr 19, 2018 at 13:36
  • That sucks @JessCokeley! More information needed: does the white smoke start right away, or does it only happen once the engine heats up? Do you get smoke out of the tailpipe? Look under the bonnet, and under the engine, do you have any obvious fluid leaks? When it's making smoke is there an obvious source?
    – GdD
    Apr 19, 2018 at 13:48
  • 2
    Petrol smells very different from motor oil. Motor oil, especially burnt one, has a thick, acrid smell. Gasoline doesn't.
    – Al_
    Apr 19, 2018 at 15:55

1 Answer 1


Smoke under the hood can be caused by many things. It is commonly caused by oil leaking into the exhaust manifold(s) from the valve covers where the gaskets have gone bad. Another common reason is sloppy adding of oil that missed the filler. You will have to identify it to know for sure.

As far as the smell coming from the vents, on most cars the fresh air intake for the cabin is located in close proximity or the engine compartment. Therefore, when the smoke from the burning oil is present, it can be pulled into the fresh air for the cabin, thus allowing the smell to come thru the vents.

You will need to inspect the engine for leaks. Once you have found them, please update your question so we can help with more detail. Hopefully it is just valve cover gaskets, which can be a simple, inexpensive fix.

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