My car's temperature gauge has been running a bit high lately. Before I panic, I want to check the cooling system DIY style. What are the basic cooling system DIY checks I should do? I know about checking coolant levels, but what else should I look at? Any tips for flushing the system myself?
Cooling system DIY checks: coolant level (cold engine only), coolant condition (should be clean, not muddy), radiator cap seal, hoses for cracks/softness, radiator fins for debris, thermostat operation, water pump for leaks. For flushing: drain old coolant, flush with distilled water until clear, refill with proper coolant mix. Never mix coolant types.
If your temp gauge is running high, check: radiator fan operation (should come on when AC is on or engine hot), thermostat (stick it in boiling water to see if it opens), coolant concentration (use a tester). Also, make sure the radiator isn't blocked by leaves or bugs. A garden hose can clean the fins gently.
When doing cooling system DIY work, always use distilled water, not tap water. Minerals in tap water can cause scaling and corrosion. Also, burp the system after refilling - air pockets can cause overheating. Most cars have a bleeder valve, or you can let the car run with radiator cap off (cold engine) until thermostat opens and bubbles stop.