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Old 04-17-2012, 12:15 AM   #7
av8r
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City: Anacortes
Vessel Name: Selah
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Join Date: Dec 2011
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Pickeling an aircraft engine or fogging a marine engine are both done to coat the valve train and cylinder walls with a thin coat of oil to prevent rust during periods of inactivity. Pratt & Whitney recommended pickeling radial engines for more than 2 weeks of down-time.
Pratt R-2800s and Wright R-2600s both have a fitting below the carburetor to inject oil for pickeling. With the oil dispenser connected to this fitting through a valve, the engine is run at idle. The valve is slowly opened and oil is sucked into the intake airstream. Over a few minutes the oil flow is increased until the engine stalls. Yes, it is very smokey. We learned to let the Port of Everett fire department know when we were pickeling engines, because if we didn't we would see the fire trucks shortly.
After the engines stalled, one plug was pulled in each cylinder and the cylinder was filled with oil. The carburetor inlet and exhaust pipes were sealed with tape. For long-term storage a silica gel packet would be inserted into each exhaust pipe before taping.
A gasoline marine engine can be fogged the same way, but a diesel engine generally has to be fogged by running the engine on fogging oil since there are no spark plugs that can be remove to fill the cylinders with oil.
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