* A cracked or failing pressure cap: This is the simplest and cheapest fix to check first. The pressure cap maintains pressure in the cooling system, preventing boiling and coolant loss. If it's faulty, pressure builds, forcing coolant out through the overflow reservoir and potentially spraying it onto the engine.
* A blown head gasket: This is a more serious problem. A blown head gasket allows coolant to mix with engine oil (resulting in milky oil) or to leak into the combustion chambers (leading to white smoke from the exhaust). The pressure from combustion can force coolant out through the weakest point, which may be the reservoir.
* Cracked engine block or cylinder head: Similar to a head gasket failure, a crack in the engine itself allows coolant to escape under pressure. This is usually accompanied by other symptoms like overheating and loss of coolant.
* Radiator cap issues (though less likely to spray): While the reservoir cap is the most common culprit for spraying, a faulty radiator cap can also contribute to excessive pressure buildup, though it would likely result in a leak at the radiator rather than spraying from the reservoir.
* Faulty water pump: While less likely to directly cause spraying, a failing water pump can restrict coolant flow, leading to overheating and potentially forcing coolant out through the reservoir.
How to diagnose:
1. Check the pressure cap: Inspect the pressure cap for cracks, damage, or corrosion. Replace it with a new one that meets the correct specifications for your vehicle. This is the easiest and cheapest first step.
2. Inspect the coolant for signs of oil contamination: Check the dipstick for milky or brownish oil. Check the coolant reservoir for oil slicks. This strongly suggests a blown head gasket.
3. Pressure test the cooling system: A mechanic can perform a pressure test to pinpoint leaks in the system. This will help identify if the leak is from the cap, the radiator, a hose, or a more serious problem like a head gasket or crack in the engine.
4. Look for external leaks: Carefully inspect all hoses, clamps, and connections for leaks. Look for signs of coolant on the engine block, cylinder head, or elsewhere in the system.
5. Monitor temperature: Watch the temperature gauge closely while the engine is running. Overheating is a strong indicator of a more serious underlying problem.
Recommendation: A cracked pressure cap is the most likely and least expensive solution. Replace it. If the problem persists, take your Aurora to a qualified mechanic for proper diagnosis and repair, particularly if you suspect a blown head gasket or cracked engine block/head. These are expensive repairs.
