Here are some of the most likely culprits:
* Head Gasket Failure: This is a serious issue. A blown head gasket allows coolant to mix with oil (resulting in milky oil) and/or enter the combustion chamber (causing white smoke from the exhaust). The location of your leak (under the manifold) makes this a strong possibility.
* Cracked Cylinder Head: Similar to a head gasket failure, a crack in the cylinder head can allow coolant to escape. This is also a significant repair.
* Leaking Intake Manifold Gasket: The intake manifold sits atop the engine and is prone to gasket leaks. Coolant passages often run through or near the intake manifold, so a leak here could explain the location of your drip.
* Water Pump: While less likely to leak *from the top* of the engine under the manifold, a failing water pump *could* leak coolant in this area depending on the exact location of the leak within the water pump housing itself and the way the coolant runs.
* Thermostat Housing: A crack or leak in the thermostat housing can cause coolant to escape, often near the top of the engine.
* Coolant Hoses: While less likely to be the sole cause of dripping *under* the manifold, a compromised hose *near* the manifold could contribute to the leak. Check all hoses for cracks, bulges, or looseness.
Before you take it to a mechanic:
* Don't drive it extensively. Driving with a coolant leak risks overheating, which can cause catastrophic engine damage.
* Check your coolant level regularly.
* Look for signs of overheating. Does your temperature gauge rise? Is there steam coming from under the hood?
* Check your oil. If the oil is milky or brown, this strongly suggests a head gasket or cylinder head crack.
Because pinpointing the exact cause without a visual inspection is difficult, taking your Chevy Malibu to a qualified mechanic is absolutely essential. They'll be able to diagnose the problem accurately and provide the necessary repair. Delaying this could be very costly in the long run.
