Depreservation of an Engine Inspection and Depreservation of Accessories After the engine has been secured to an engine stand, all  covers must be removed from the points where the engine was  sealed or closed with ventilatory covers, such as the engine  breathers, exhaust outlets, and accessory mounting-pad cover  plates. As each cover is removed, inspect the uncovered part  of the engine for signs of corrosion. Also, as the dehydrator  plugs are removed from each cylinder, make a very careful  check of the walls of any cylinder for which the dehydrator  plug color indicates an unsafe condition. Care is emphasized  in the inspection of the cylinders, even if it is necessary to  remove a cylinder. On radial engines, the inside of the lower cylinders and  intake pipes should be carefully checked for the presence of  excessive corrosion-preventive compound that has drained  from throughout the interior of the engine and settled at these  low points. This excessive compound could cause the engine  to become damaged from a hydraulic lock (also referred to  as liquid-lock) when a starting attempt is made. The check for excessive corrosion-preventive compound in  the cylinders of reciprocating engines can be made as the  dehydrator plugs are removed from each cylinder. Much of  the compound drains from the spark plug holes of the lower  cylinders of a radial engine when the dehydrator plugs are  removed. But some of the mixture remains in the cylinder head  below the level of the spark plug hole and can be removed  with a hand pump.  [Figure 8-3]  A more positive method is  to remove the lower intake pipes and open the intake valve  of the cylinder by rotating the crankshaft. This latter method  allows the compound to drain from the cylinder through the  open intake valve. If excessive compound is present in an  upper cylinder, it can be removed with a hand pump. The oil screens should be removed from the engine and  thoroughly washed in an approved solvent to remove all  accumulations that could restrict the oil circulation and cause  engine failure. After the screens are cleaned, immerse them  in clean oil and then reinstall them in the engine. When the cover has been removed from the intake area, the  silica gel desiccant bags (used to remove moisture from the  engine in storage) must be removed from the engine area. If  the engine uses a propeller, remove the protective covering  from the propeller shaft and wash all corrosion-preventive  compounds from both the inside and outside surfaces of the  shaft. Then, coat the propeller shaft lightly with engine oil.  Turbine engines require the removal of several covers on  many external areas on the engine. As a final check, see that the exterior of the engine is clean.  Usually a quantity of compound runs out of the engine when  the dehydrator plugs and oil screens are removed. To clean  the engine, spray it with an approved commercial solvent. An engine’s performance is no better than that of its  accessories. Though the engine has been completely  overhauled and is in top condition, any oversight or error  in installing the accessories can result in improper engine  operation or even irreparable damage to it. Before depreserving any of the accessories enclosed with  the engine, consult the storage data usually stenciled on the  outside of the engine container or the records enclosed with  the engine to determine how long the engine and accessories  were in storage. Certain accessories that normally accompany  an engine from overhaul are considered unsafe for use if their  time in storage has exceeded a specified period. This time  varies according to the limits prescribed by the manufacturer. Any accessory that has been removed from an old engine that  can be installed on the new one must be given a thorough  inspection to determine its condition. This inspection  includes a check for general condition, cleanliness, absence  of corrosion, and absence of wear as evidenced by excessive  play in the moving parts. Some accessories must be replaced, regardless of their  operating time, if the engine is being changed because  of internal failure. Such accessories may have been  contaminated by metal particles carried into their operating  mechanisms by the engine oil that lubricates them. Before installing any replacement accessory, check it  visually for signs of corrosion and for freedom of operation.  Figure 8-3.  Draining corrosion preventive compound. 8-5