Q: My radiator boils after the car has stopped. The cap has been replaced, thermostat, fan sensor, etc. 2006 Chrysler PT Cruiser

Hi there - the "boiling after shutoff" symptom is evidence of excess engine heat which is not being radiated by the radiator. Most likely, the "sealant" you added to the cooling system prior, is biting you back. The leak sealant coatings inside the cooling system added by this sealant, reduces both ability of the engine to shed heat to the coolant, and to transfer heat to the radiator fins (and outside air) to get heat out of the cooling system. I recommend both a coolant system flush to get the sealer out of the system, and a leak inspection so that the source of the leak can be determined and fixed. I suggest you get this done by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

Hi there. Although it’s designed to plug a leak, in most cases, radiator ’leak products’ tend to do more harm than good. It’s quite possible that the sealant leak material is clogged somewhere in the cooling system; possibly in the heater core. It’s probably a good idea to have a professional mobile mechanic come to your location and complete a car is overheating inspection, to determine why you’re car is having this problem.