RRyder01

This is probably a stupid question, but can a large vac leak cause overheating? I just replaced the hose that goes under the upper intake manifold, and now my car runs cooler (overheated once and has been running hot since) and my idle (after reset) is nearly perfect. Just wondering...

PJC Racing

Yes to a degree, will it make it overheat on it's own? IMO, no. It will help a poor cooling system overheat. But a vacuum leak will make an engine run hotter be cause the leak will lean out the fuel mixture.