car smells bad when running

[Lee Levitt]

Kent writes:

> Stick you finger
>    in the coolant overflow tank and smell it.

Um, that is not a great idea. Coolant can be toxic to domestic animals and it probably ain't great for humans either.

The OP may not be able to distinguish between good and bad coolant based on the smell, so conducting this particular diagnostic may not be helpful.

She should conduct the visual inspection as described and hand off the car to her trusted indie mechanic.

I'm betting on a head gasket leak. 

Best,

Lee