Causes of Coolant Leaking From the Engine Manifold

by Naomi Bolton
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Coolant leaks are often the cause when a car's engine overheats. A leak can occur anywhere in the cooling system and is usually easy to find, as the coolant can often be seen spraying, seeping, bubbling or dripping from the leaky component. Depending on the type of antifreeze used in your car, coolant color can vary between green, orange and yellow. The engine manifold consists of a series of tubes that are attached to the carburetor and several engine parts.

Intake Manifold Gasket

Several gaskets seal the connection between the intake manifold and the cylinder heads. When these gaskets fail coolant will enter the crankcase or intake port, or drip down the outside of the engine. Intake manifold gaskets on many general engine models are made from plastic, and typically fail between 50,000 and 80,000 miles.

Damaged Hose

A series of hoses connect the manifold with other engine parts. An old, cracked hose is a common cause of a coolant leak. A cracked and leaky hose must be replaced.

Bad Head Gaskets

The head gasket connects the engine block with the cylinder head. Coolant can leak into the crankcase and dilute the oil, damaging bearings in your engine. A head gasket leak can also foul the spark plug and cause a lot of white exhaust smoke. Add sealer to the cooling system in an attempt to plug the leak temporarily, but arrange for the head gasket to be replaced in the meantime.

Cracked Head or Block

A cracked engine block can cause internal coolant leaks, which will often dilute the oil on the cylinder walls and damage piston and rings. If your car's antifreeze contains silicates, it can also foul the catalytic converter and oxygen sensor. If a lot of coolant leaks into the cylinder, your engine may "hydrolock" and refuse to crank when you try to start it.

Corroded Freeze Plugs

Freeze plugs are often situated just behind the exhaust manifold. Coolant leaks from these plugs may seem like it is coming from the manifold itself. Freeze plugs are the expansion plugs in the side of the engine block and cylinder head, and often corrode from the inside out.

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