<VV> heater exhaust smell.

[Smitty]

From: jeandelucca at aol.com

i am zeroing in on what i believe to be an exhaust leak based on the smell 
the heater of my 63 is producing. i have a set of manifold exhaust donuts to 
install, but am wondering about the likelihood of a cracked manifold or 
rotted exhaust tube. the car otherwise runs fine and strong and is not loud 
at all, all hoses are new and intact. any toughts/ comments? thanks, jim
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Smitty Says;  If the smell is worse when the heater is on, then there are 
few places that can leak and you smell it.  Usually even the manifold to 
crossover pipe donuts won't be smelled when leaking because they are outside 
of the engine's cooling system.  In other words, the engine cooling fan is 
pressurizing the lower shrouds and air is being blown out of them, 
overcoming what might leak in.  So that leaves just the exhaust tubes and 
(horrors) a head gasket leak.  Since you will be in there changing the tube 
donuts anyway, get your CSI flashlight and check the joint where the head 
and cylinders come together.  If there is a gummy black deposit or 
accumulation on any of the cylinders at that point then you likely do have a 
leak there.  One clue about head gasket leaks is that they can be pretty 
rank when you first fire up the engine, but the smell sort of goes away as 
it warms up.
If you don't have leaks at the heads or exhaust tubes then other possible 
ways to get smells from exhaust inversion to the top of the engine.  A 
straight out the back tail pipe can cause this.  Turbos are sometimes bad 
about leaking exhaust from leaking plumbing and into the fan.  Bad air seals 
around the engine can allow inversion.  I'm betting on the tubes or head 
gaskets.