Volkswagen Repair: 1979 VW bus camper exhaust smell, heat, exchanger

Question
I just bought a 1979 VW bus that has a really bad exhaust smell in the cab when I am driving it.  When I turn the heater on it is much worse and cannot even drive it without getting sick.  How can I fix this? Thanks, Ryan

Answer

Bus_exchanger It likely your heat exchanger(s).  There are 2, one below each engine head, connected to the exhaust tubes, in and out, then to the engine fresh air fan, and finally the hot air supply hose going to the passenger compartment.  Either the exchangers are rusted/cracked internally, or a hose(s) is not on tightly or even disconnected.   Of course the first scenario is the worse, they are about $300 each, unless you are good working with metal repair/welding.  The second situation can be easily rectified, you just have to get under the rear of the bus and in the engine compartment to track down the offending hose/connection.  
 Another possibility is exhaust is entering the engine compartment because of bad/missing compartment sealing.  That's another reason it's never a good idea to dispense with the tin surrounding the engine for the sake of accessibility/laziness.  Yes, the fresh air source, believe it or not, is the engine fan; therefore exhaust in the engine compartment, then exhaust in your heater system.  Good luck, let me know what you find...