1. Identify the Leak:
* Visual Inspection: With the engine cold, carefully examine the entire cooling system. Look for:
* Obvious leaks: Wet spots, drips, or trails of green/orange/yellow (depending on your antifreeze type) liquid. Pay close attention to hoses, clamps, the radiator, water pump, thermostat housing, heater core hoses (inside the car, under the dash – this is a difficult-to-reach area), and the radiator cap.
* Pressure Leaks: These are harder to spot and might only appear when the engine is running and the system is under pressure. A pressure test (see below) is best for this.
* Smell: Sweet smelling liquid is a telltale sign of antifreeze.
* Check the coolant level: Regularly check the coolant reservoir to see if it's dropping.
2. Test for Pressure:
* Pressure Test: This is the most effective way to pinpoint a leak. A radiator pressure tester is relatively inexpensive and available at most auto parts stores. It attaches to the radiator cap and pressurizes the system. Leaks will become apparent. *Do this with the engine cold.*
3. Common Leak Points and Solutions:
Based on your findings, here are some likely culprits and their fixes:
* Hoses: Cracked, brittle, or loose hoses are common culprits. Replacement is usually straightforward and inexpensive. Clamp tightness is crucial.
* Clamps: Worn or broken clamps can allow hoses to leak. Replacement is simple and cheap.
* Radiator: Leaks can be small pinholes or larger cracks. Repair might be possible with a sealant (a temporary solution) or the radiator may need replacing.
* Water Pump: Leaks typically occur around the shaft seal. A leaking water pump requires replacement.
* Thermostat Housing: Cracks or a failing gasket can cause leaks. Replacement is usually straightforward.
* Radiator Cap: A faulty cap can fail to maintain proper pressure, leading to leaks or boiling over. Replace if suspect.
* Heater Core: This is located inside the dashboard and is the most difficult to access and repair. A leak usually results in antifreeze in the car's interior, often on the passenger side floor. This often requires dashboard disassembly for replacement.
* Head Gasket: A blown head gasket is a much more serious problem, often resulting in antifreeze in the engine oil or vice versa (oil in the coolant). This requires professional attention and is a costly repair. Look for milky oil or foamy coolant.
4. Repairs:
* Minor repairs (hoses, clamps, radiator cap): You might be able to tackle these yourself with basic tools. Consult a repair manual or online videos for guidance.
* Major repairs (water pump, thermostat, heater core, radiator, head gasket): These often require specialized tools and expertise. It's best to take your car to a qualified mechanic.
Important Considerations:
* Safety: Antifreeze is toxic. Wear gloves and eye protection when working on the cooling system. Dispose of old antifreeze properly according to local regulations.
* Repair Manual: A repair manual specific to your 1999 Chevrolet Malibu is invaluable. It will provide diagrams, torque specifications, and step-by-step instructions.
* Mechanic: If you're not comfortable working on your car yourself, take it to a reputable mechanic for diagnosis and repair.
By systematically checking these areas, you should be able to locate the source of your antifreeze leak and get your 1999 Malibu back on the road. Remember safety first!
