Have you ever had this coolant leak before ?

[travlnman]

Was planning on removing the head on my '78 Z (stock) . Suspected blown head gasket, due to need to fill overflow after every drive, with no visible leaks. Evidence of burning something due to residue on all plugs. Puff of smoke from tailpipe when I added stop leak to radiator after thermostat opened. No water in oil, but maybe some slight evidence of moisture in the baffle of the rocker cover.

 

After removing rocker cover, plugs and all associated hoses and wires, I removed the throttle body. The throttle body was completely soaked on the backside of the butterfly, and I was able to pout water from the orifices leading to the now removed BCDD. The only source of coolant in this area is what I believe is called the TVV. A temperature controlled valve for the EGR system, that is threaded into a housing with coolant circulating through it. Has anyone ever known this valve to fail internally, and let coolant bypass and be sucked into the vacuum line for the EGR ?

 

The entire intake tract was wet, and if the problem was the head gasket, I cannot see how coolant would get into the intake tract . The car has no overheating, and runs hard with no issues otherwise. Anybody ever seen anything like this ? Thanks for the help.