Coolant disappearing...

[540s10]

loses about a quart every 300 miles, I can smell vaporizing coolant under the hood, and when I had the fan shroud off I could see that the fins on the bottom tubes of the radiator were missing.

can I be fairly sure its the radiator leaking a minute amount and its not a cracked head?

 

[vail426]

Coolant crossover gaskets are prone to leaks. Usually evaporates before reaching the ground. Look closely at that area. Pressure test is helpful also.

 

[SmithvilleD]

Sometimes the old tailpipe sniffer's used to set carb idle mixture will detect small amounts of exhaust gas in a radiator or overflow throat w/ the cap off. Not always, but I had that work in a couple instances where there weren't obvious combustion gas bubbles consistently appearing.

If there's a shop around you that's been in business long enough to still have one of those sniffer's around, it's quick & easy to pop the pressure cap, put the probe in the neck & see if it registers any exhaust gases.

 

[Turbine Doc]

possibly the mickey mouse GM quick disconnect at coolant crossover leaks then seals up from time to time, o-rings turn to square rings, then fitting rots many have replaced with a 5/8" barb x 1/2 NPT male fitting