i have a diesel smell in my cab when i let my truck sit there an idle with the defrost on. Anyone know why?

 

I have the same problem. Will be watching this thread.
Sorry no answer

 

Hole in up pipe possibly. Check under your hood for signs of soot. If your getting diesel fumes in the cab that is the most likely cause.

 

I had the same. I just figured out it is my fuel filter lid leaking in the engine compartment.

 

Does it smell like diesel exhaust or diesel fuel? The regulator on the filter bowl was leaking on my truck awhile back. Would only smell diesel sometimes until it got really bad, it wont leave a puddle either. It wont leak if the trucks not running. Took me about 15min to replace the oring and problem solved. You can find it on the front of the fuel filter bowl on top of the motor. It has 4 small screws holding the cover on and a fuel line on it.

 

I had this same prob too but mine was a torn turbo hose. Replaced it and prob solved.

 

the stainless steel y pipe to the turbo have a tendency to crack behind the heat shield like BC said , check for soot on the fire wall and along the manifold mounting studs