Soot on Underside of Hood

I have a 1997 Saturn SL SOHC, 5 speed manual with 98,000 miles. A month ago I had the oil changed and they service tech said I need to replace the timing belt, which I did.

Recently I refilled the windshield washer reservoir and notice the entire underside of the hood is covered with soot. What can cause this and is it safe to drive this vehicle?


Are you sure it is soot? This type of thing is normally engine oil pushed out be a malfunctioning PCV system or a leak in the valve cover gasket, or the oil filler cap or dipstick not put back in correctly. Soot could be from a leaking exhaust system under the hood. In that case the engine would be noisy.

I’m also puzzled as to why a timing belt change could cause soot under the hood, unless the technician scraped the guck from inside the timing belt cover and depOsited it under hood without cleaning up the mess he made. This is a very good reason to open the hood and inspect the car right after you take delivery from the service department.

Is there a pattern to this “soot”? Does it appear to be slinging off a belt or moving part? Could this “soot” actually be ground up belt material?

Is it just a light powdery coating of black stuff? A lot of cars get this over time and as far as I know it’s normal. Try wiping it off and see if it comes back.

Thank you for your message. The soot is uniformly deposited over most of the underside of the hood. It is not from the oil cap or dip stick.

The service engine light occasionally comes on but goes out after a few days - usually in wet or humid weather.

The engine is a little noisy.

The soot is not oily - dry powder.

Thanks again.

Noiser engine? Is the inside of the tail pipe sooty, also? Have your mechanic check the tube to the egr valve (in the engine compartment), and the egr valve, itself, for leaking exhaust.