How do you tell if your radiator cap is faulty?
take the cap off and check this look under the cap and see if the rubber seal is broken or it looks worn but if in doubt replace it a mechanic has tool for connecting to radiator to check cap pressure. but if you think radiator cap is the problem, just buy a new one they cost under 10 bucks. if that is the problem, it is sure cheaper than going to a mechanic
to add to this, a big YES,on the radiator cap .the radiator cap needs to be specific pressure rating. radiator caps do wear out. also the cheapest fix to start It is doubtful a radiator cap would cause a car to overheat. Common overheating causes are insufficient coolant, leaking coolant (into or out of your engine), faulty thermostat, blown cooling fan fuse, faulty fan temperature switch ( sender ), faulty fan, or a faulty fan…
I presume you mean car water pump? If the water pump is faulty the car will over heat and the temperature gauge will go up. Make sure that there is enough coolant in the radiator, the radiator or the hose pipe is not leaking and the radiator cap is not faulty, as all of these faults can cause overheating. Once you have excluded these then you can blame the water pump.