I have a 2003 chevy duramax that is leaking large amount of oil from breather tub in front right side of engine

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Customer: I have a 2003 chevy duramax that is leaking large amount of oil from breather tub in front right side of engine
Answered by John in 4 mins 12 years ago
40+ years of experience

6,206 satisfied customers

Specialities include: Automotive Mechanic, Small Engine Repairs, Auto Body Repairs, Diesel Engine Repairs



This sounds like the crankcase is building too much pressure possibly due to a component failure.


Crankcase Ventilation System Inspection/Diagnosis



DEFINITION: During normal operation the crankcase gases can be seen exiting from the hose at the oil separator.

The maximum crankcase pressure is 4 kPa or 16 in of water at 3,100 RPM measured at the oil level indicator tube.

Oil leak - external

Plugged or kinked crankcase ventilation system hoses
Damaged or loose crankcase ventilation system hoses
Valve rocker arm diaphragm covers loose
Oil separator oil drain hose damaged or loose
Too much crankcase pressure

PCV check valve (bottom of generator bracket) stuck closed

Valve closes when 1.47 kPa (0.213 psi) of crankcase pressure is applied from the crankcase side (bottom) of the valve.
Valve should allow oil to drain from the separator during idle and engine off conditions.
Inspect for proper operation by stopping engine and waiting 5 minutes to allow the oil to drain back into the crankcase. Remove the drain hose from the check valve. If more than residual oil (several drops) drains from the separator, replace the valve.

Restricted Positive Crankcase Ventilation vent hole inside the PCV separator (if equipped)

Confirm the vent hole, if equipped, or area between the bracket and block is not restricted with dirt, ice, or debris.


Normal situation


Cracked hoses


Internal engine failure

Also check the oil level & if there seems to be fuel in the engine oil it is possible that you could have a fuel injector problem.There has been a large amount of them fail.
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