Can Water Get in Oil From a Blown Intake Gasket?

by Chris Stevenson

The automotive intake manifold functions as a passage to route atomized fuel into the cylinders for purpose of combustion. The intake manifold requires a gasket to seal the manifold against the cylinder head. On V-type engines that bolt and seal directly to the head, a fiber or metal-fiber gasket makes the vacuum and fluid-resistant seal. These types of engines have water passages, typically running from the front and rear of the intake manifold that circulates coolant. Under certain circumstances, water can enter into the oil pan as a result of a blown intake manifold gasket.

Intake Manifold Location and Design

On the V-type engines, intake manifolds are made of cast aluminum, iron and, in some cases, plastic. They sit directly mid-engine between the heads. The manifold has two angled mating surfaces, one for each head bank. Large bolts must be properly torqued to specifications to connect and seal the intake manifold to the cylinder head. The intake manifold gasket has rear and front water passages, joining the manifold with the head, to allow coolant to flow and cool the cylinder head, as well as large fuel port openings and bolt holes.

Water in Oil Symptoms of a Blown Intake Manifold Gasket

A blown intake manifold gasket shows itself by the condition of the engine oil when checked with a dip stick. If the vehicle has an oil leak, the oil will also appear altered in color and texture. Water-contaminated oil will look light brown and exhibit a frothy or creamy texture the consistency of a milkshake. The frothy texture results from churning and air in the oil. Oil will not necessarily enter the cooling system with a blown intake manifold gasket.

Reasons for Gasket Failure

Intake manifold gaskets are designed to crush upon the torque applied to them between the head and manifold, forming a seal. Temperature fluctuations during constant engine heating and cooling can warp the manifold contact surface and allow gasket leakage. Age can cause the eventual deterioration of the gasket material, allowing a split or break. Severe engine overheating can warp the manifold or head, causing leakage as well as burning the gasket material. Corrosion and rust in a water passage can weaken and disintegrate gasket material.

Location of Gasket Failure

Engines that have a one-piece manifold-to-head seal without a lifter valley cover will leak on the inner edge of the gasket close to the coolant passage. Coolant will bypass the gasket seal and leak down into the lifter valley. The coolant will proceed to drop into the oil pan and collect there. Some model vehicles do not have such a passage, or have the lifter valley sealed off by a separate cover.

Gasket Failure Consequences

When the intake manifold gasket breaks and allows coolant to mix with the engine oil, the oil becomes diluted and loses its viscosity. Depending upon the severity of the leak, the engine might run hot. The radiator or overflow coolant reservoir level will drop noticeably. Water-contaminated oil will raise the engine temperature through increased friction. Connecting rods, crankshaft bearings, camshaft bearings, valve train rockers and shafts, valve stems and other major metal components will begin to fail. Water-contaminated oil leads to eventual seizing, galling and breakage of major engine components.

About the Author

Chris Stevenson has been writing since 1988. His automotive vocation has spanned more than 35 years and he authored the auto repair manual "Auto Repair Shams and Scams" in 1990. Stevenson holds a P.D.S Toyota certificate, ASE brake certification, Clean Air Act certification and a California smog license.

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