Technical Service Bulletins

Pop Goes the Rear Mainseal

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Pop Goes the Rear Mainseal

Some owners of 2011 Buick Regal vehicles equipped with a 2.4L engine may complain of an engine oil leak that appeared in extremely cold ambient temperatures (generally 0 degrees Fahrenheit or colder). They may also comment that they heard a single “pop” noise immediately before the oil leak started.

Upon inspection the technician will find that the oil leak is coming from the engine’s rear main oil seal. This may be the result of a frozen PCV system and excessive crankcase pressure that caused the seal lips to fold rearward.

Determine if the concern is the result of a frozen PCV system by inspecting the PCV system, dipstick and engine oil fill cap for signs of ice, moisture and/or sludge buildup.

1. Check for proper thermostat operation.

2. Remove the cam cover, inspect the PCV baffle and replace the cam cover if obvious sludge buildup is present.

3. Clean any ice/sludge/water out o the PCV pipes/hoses, the PCV nipple between the #2 and #3 intake runners and the throttle body. Also inspect the related PCV hoses/connections for potential damage and replace if necessary.

4. Allow the engine to idle at operating temperature for at least 15 minutes, turn the engine off and drain the engine oil for at least 15 minutes to remove all oil and condensation/water from the crankcase.

5. Follow SI repair procedures to repair any oil leaks that were induced as a result of the frozen PCV system and excessive crankcase pressure.

6. Clean any oil residue left under the vehicle from the original oil leak.

7. Replace the oil filter and fill the crankcase with engine oil. In the future, the customer should consider changing the engine oil before winter begins in order to prepare for the colder weather.

8. To complete the repairs, ensure that the latest ECM calibrations have been installed to adjust the engine oil life monitor to a maximum of 7,500 miles.

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