radiator over heating

Since that resivour is not pressurized and the cap pulls right off I doubt it If you cat overheated it was Low on coolant Or the system was malfunctioning Or you have a head gasket leak If it runs fill w coolant burp the motors to get rid of air Fill tank to correct level. Out a cap on that They are dirt cheap in a parts store Drive it watch the gauge and determine if overheating again If so have the system checked at a radiator shop

It's very unlikely that the engine will overheat because of the recovery tank cap being left off. A non pressurized recovery tank is simply a holding tank for coolant and makes it easier to check your coolant level. If the tank was empty that means you were low on coolant in the radiator and that's why the engine overheated. When you have a leak the coolant level goes down in the radiator. Coolant is pulled from the recovery tank to make this up. When the recovery tank is empty and the coolant level continues to drop because of a leak the engine will overheat. Hope that helps! Jim