Locate your car's engine coolant reservoir. If you don't know where this is, consult your vehicle's owner's manual. Search for a detailed, labeled diagram of your car's engine and pinpoint the location of the engine coolant reservoir.
Perform a visual inspection of all the connection points where hoses are attached to the coolant reservoir. Look for broken connections, hoses that are degrading and any cracks in the rubber of the hoses or gaskets. If you find any, fixing the problem may be as simple as draining the cooling system, replacing the faulty parts and refilling your engine with coolant.
Turn your car's ignition on and have another person press down on the accelerator to create exhaust. Watch to see whether there's any white smoke emerging from your car's tailpipes. The presence of white smoke may indicate that you have a faulty head gasket, and there's a coolant leak that's draining into your combustion chamber.
Check for coolant leaks by refilling your car's coolant system, ensuring that it is filled to maximum capacity. Then, drive normally and check your coolant levels a few days later (or after you've driven about 100 or 200 miles). If the coolant levels are low or the coolant chamber has emptied, it is a virtual certainty that your coolant is leaking into another part of your engine.
