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- Aug 18, 2008
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Looking through my old MEB magazines today I noticed a small "tip" about not storing model engines with detergent oil in them. The tip indicated that this leads to internal rusting. The rusting potential inside model engines is very real, but I would suggest that it isn't due to the type of oil used, but rather maintenance that is not provided.
The rusting potential is usually limited to enclosed crankcase wet sump engines. Water is a major component in combustion gases. The moisture in blowby gases will rapidly condense in the cool crankcase of an engine. In a normal engine that reaches operating temperatures, this is a not an problem. The moisture is driven off. However, condensed moisture accumulates in engines where the oil temperature never gets much above ambient temperature. This condition is common in propane forklift truck engines in intermittent service, and in model enignes run for short demo periods. You could run your engines longer and allow the oil to get hot and drive off the water. In most model engines, this is not practical. Regular maintenance is then required. My preferred maintenance is to drain the engine oil after any significant usage (but short runs can be the worst), and flush the crankcase with a water displacing fluid like WD-40. Draining the oil without flushing, will not remove all of the emulsified oil/water inside the engine. Over time, the tiny little water globules form together into larger water globules causing corrosion. Don't forget to refill the engine with oil, and then put it away (out of site) so you won't be tempted to run it again. I know the temptation well.
An even more aggressive corrosion potential exists in the upper cylinder area after very short cold runs. A spritz of WD-40 through the spark plug hole and then a mild blast of compressed air coates this area and protects it. Just my thoughts.
Jeff
The rusting potential is usually limited to enclosed crankcase wet sump engines. Water is a major component in combustion gases. The moisture in blowby gases will rapidly condense in the cool crankcase of an engine. In a normal engine that reaches operating temperatures, this is a not an problem. The moisture is driven off. However, condensed moisture accumulates in engines where the oil temperature never gets much above ambient temperature. This condition is common in propane forklift truck engines in intermittent service, and in model enignes run for short demo periods. You could run your engines longer and allow the oil to get hot and drive off the water. In most model engines, this is not practical. Regular maintenance is then required. My preferred maintenance is to drain the engine oil after any significant usage (but short runs can be the worst), and flush the crankcase with a water displacing fluid like WD-40. Draining the oil without flushing, will not remove all of the emulsified oil/water inside the engine. Over time, the tiny little water globules form together into larger water globules causing corrosion. Don't forget to refill the engine with oil, and then put it away (out of site) so you won't be tempted to run it again. I know the temptation well.
An even more aggressive corrosion potential exists in the upper cylinder area after very short cold runs. A spritz of WD-40 through the spark plug hole and then a mild blast of compressed air coates this area and protects it. Just my thoughts.
Jeff
