Can a broken radiator cap cause a 2005 honda to overheat

If your engine is overheating, Try this procedure:

• Dirt and debris can get lodged in the radiator air flow paths. This can block the radiator and cause your engine to overheat and damage the engine.

• The thermostat can be stuck close. If you feel the upper hose very hot and the lower hose cooler than normal, it may be a stuck thermostat.

• Make sure the radiator and the overflow bottle are filled to the proper levels.

• Bleed air from the coolant system:This is best done by running the engine with the radiator cap off until you see when the air bubbles stop coming up.

• Check the radiator fans: The easiest way is to turn on the cars air conditioner and turn up the A/C fans. Both radiator fans should come on when the A/C starts

• Make a pressure test by using a pressure testing tool (available at most auto parts stores). Use the pressure shown on your radiator cap. Most cars are 16 PSI or less, so don't exceed that pressure. Replace the radiator cap if it doesn't hold the pressure.

To answer yr qustn, yes a radiator cap can & will make yr car overheat if it blocked or foulty or dasn't fit properly as the water will escape and yr system will be left empty or short on water & coolant. The cap on it on is a breather that can get blocked wich will make yr car overheat, also check the spring on it, if all that is fine go with the above solutions. G/luck. Tony

Well... your radiator cap should fit properly so start there. If that doesn't work the next step would be to change the radiator valve which should have been done when you changed the radiator... but if they gave you a cap that doesn't fit, why should they do anything else right. You can also change the tempeture valve going into the engine... it may be recording wrong. good luck