[Richard and Rhonda]

Do you smell exhaust or diesel? I know you said exhaust, but some can't or don't differentiate the smells. In addition to the obvious inspection the others have mentioned, you should see black soot anywhere you have a diesel exhaust leak.

Don't overlook the aquahot for a diesel leak, even if you aren't running it in the summer, the diesel fuel can leak there. I say this because I had a diesel odor problem related to a split fitting in the AH.