If you find that your system is low on coolant, use a coolant that meets the requirements which is required for your vehicle. When adding water, use distilled water. Distilled water does not contain any additives which can cause your coolant system to corrode or plug up over time.

Difficulty Level

Ways a head gasket can leak:

1. Between the water jacket and combustion chamber
2. Between the water jacket and oil passage hole
3. Between the water jacket and the exterior of the engine
4. Between two or more combustion chambers
5. Between an oil passage hole and the exterior of the engine

What to look for:

1. Between the water jacket and combustion chamber:
• coolant level going down
• bubbling in the radiator or expansion/reservoir tank
• steam out of the exhaust pipe
• coolant residue or beige crusty surface on the spark plug
• engine running hotter than normal operating temperature
2. Between the water jacket and oil passage hole
• coolant level going down
• oil level going down
• milky oil (during oil change or at the end of the dipstick)
• rusty dipstick
• milky residue under oil fill cap
• milky coolant
• engine running hotter than normal operating temperature
3. Between the water jacket and the exterior of the engine
• coolant level going down
• coolant residue on the outside of the engine block
• engine running hotter than normal operating temperature
4. Between two or more combustion chambers
• rough/erratic idle
• loss of compression
• engine running rough across the rpm range
• loss of power
5. Between an oil passage hole and the exterior of the engine
• oil level going down
• oil residue outside of the engine block
• loss of oil pressure

Tests which can be done:

1. Between the water jacket and combustion chamber
• compression test on cylinder
• leak down test on cylinder
• pressure test on coolant system
• leak down test on coolant system
• hydrocarbon test on coolant system
2. Between the water jacket and oil passage hole
• pressure test on coolant system
• leak down test on coolant system
3. Between the water jacket and the exterior of the engine
• pressure test on coolant system
• leak down test on coolant system
• run a dye through the coolant system
4. Between two or more combustion chambers
• compression test on cylinder
• leak down test on cylinder
5. Between an oil passage hole and the exterior of the engine
• visual inspection

Similar symptoms to a faulty head gasket:

• water leaked into oil sump will create a milky oil
• short distant trips or not allowing your vehicle to warm up will causing a milky substance under the oil cap
• cracked head
• cracked block
• warped head
• value or piston ring leakage will give you low compression
• coolant level dropping can also be from other components leaking on the cooling system such as a faulty clamp, hose, other gaskets, radiator, etc
• engine running hot could also be a faulty temperature sensor, plugged rad or coolant system, thermostat stuck closed, etc.