Welcome the brain Stuff front House stuff works dot Com where smart happens him Marshall Brain with today's question, is it true that a diesel engine can operate underwater while a gasoline engine cannot. You sometimes see military vehicles running in extreme conditions, and these conditions can include deep submersion during a river fording. Creating a vehicle that can run
submerged is a challenge. In order for any type of combustion engine to run, it must have a source of air and it must be able to release exhaust gases. If the water is not too deep a few feet, say, the exhaust castes can take care of themselves because they are under pressure. The air intake is usually the problem. As soon as you submerge the air intake, the engine can no longer get air and it will stop running. You can get around the air intake problem by adding
a snorkel. Military humvees often have a snorkel attached and it allows them to submerge in up to five feet of water. In order to handle submersion like this, the engine and the rest of the vehicle must be waterproofed. However, so your question changes into is it easier to waterproof a diesel engine than it is the waterproof a gasoline engine. To waterproof any off road vehicle, there are lots of
different things to think about. For example, any electrical devices like the instruments, the engine control computers, motors for fans, windshield wipers and so on, lights, battery, et cetera. All have to be sealed. Second, any venting for things like the crank case, the differential and stuff like that must also be sealed or vented at the same level as the snorkel. The fuel tank must be sealed invented appropriately, and any chamber or crevice that can fill with water
must of a drain. Assuming that all these other things have been taken care of, and assuming that the engine is waterproof, then the vehicle can run under water. In general, it's easier to waterproof a diesel engine than it is to waterproof a gasoline engine because the spark plugs and ignition system and a gasoline engine are complicated when you get them wet. These components run at high voltage, and
sealing them is harder, although it's not impossible. A diesel engine, on the other hand, has no ignition system See how diesel engines work at how stuff works for details on that. If the diesel engine has a mechanical fuel pump for the injectors and a mechanical transmission, there's also no engine control electronics to worry about. These features can make a diesel engine relatively easy to waterproof. That's why most military vehicles that ford rivers or run submerged have diesel engines.
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