Help for slip buddy

[Cooler]

Hello All, I know nothing about diesel engines. This may be nothing. A friend of mine took his sailboat out yesterday for the first time this season. Small diesel started up fine, ran for 30 min. getting out of marina and into the bay. Then, just like that, the engine revved up to a high RPM. He could not use throttle to reduce RPM, could not get on/off switch to stop the engine, no reaction to anything he tried. He finally disconnected the battery to get it to stop. Any thoughts? It is probably a low horsepower, small size, typical of snailors. Almost sounds like something disconnected. Thoughts? er

[Viper]

Sounds like a runaway diesel. A few things can cause this phenomenon but essentially it's getting fuel from a source it shouldn't be getting it from or getting more than it should be from its fuel delivery system. Keep in mind that "fuel" to a diesel engine can also be engine oil getting into the combustion chamber by several means. When this happens, it basically feeds itself and can run uncontrollably. On newer engines that rely on electrical controls, you can shut the engine down by disconnecting power but on older engines that didn't rely on electricity to make them run, shutting down a runaway isn't that easy and many have destroyed themselves in the process. Do a Google search on runaway diesels and you'll see what I mean.

[bud37]

It would be interesting to find out whether shutting off the battery actually stopped it or was it a coincidence. Only a few ways to shut off a diesel I can think of, cut off it's fuel, cut off it's air or stall ( quick overload ) or the obvious in a runaway situation would be the engine failure.

[waybomb]

Everybody with a diesel should fabricate a tight cover for the engine intake.
Especially with a turbocharged engine.
If the turbo leaks oil, you could have a runaway engine; the oil becomes the fuel. The only way to stop it - grenade the engine, run out of oil or cut off the air.

[Cooler]

Thanks all! I did Google runaway diesel,...YIKES! I think you're right Bud. Probably a coincidence as the engine was burning up. Glad there was no fire, they had a 12 year old passenger as well as a dog onboard at the time. They are not going to be happy to hear this news. It is an older snailboat, and may not support the expense of a new engine. If I see him this weekend, I am not going to deliver the news. Just going to tell him to Google runaway diesels. er