I've always been curious to know if an air leak around an intake manifold or carburetor gasket could cause the engine to run leaner and cause overheating issues. now I know unmetered air can cause idle problems and so forth with any engine but I've never correlated it to some problems I've encountered on cars I've worked on. is it feasible to conclude that an air leak is responsible for a car running hot and searching for idle?

 

A vacuum leak will definatly cause the car to run leaner. While lean mixtures do create higher combustion temperatures, that doesnt necessary mean your engine temperature will be hotter. I guess theoretically it is possible for a lean condition to cause a car to overheat, it is unlikly. Ive never heard of it happening.