Carver Owners Forum

waybomb wrote:Qr Bbpost..... Runaway's happen.....I've seen it. Pretty damn scary.

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waybomb wrote:Qr Bbpost Sounds as if you have things covered.

Something you may want to consider. Develop a way to completely block the air intake to the engine. Runaway's happen. Center bearing seal goes bad in the turbo, engine oil gets in the intake stream, and bam - it's running away from you. Only way to kill it is to completely block the airflow. Completely.

I've seen it. Pretty damn scary.

I've never seen this happen, but can imagine it. I wonder if you could put something like an RPM-triggered FM-200 system in and just plumb it to the intake? I wonder how big of a bottle you'd need?

How many cubic inches is the engine, how many rpm is it running at runaway, how much does the bottle hold, and finally, if the engine is still spinning when you run out of suppressant, it may light off again and off it goes.

waybomb wrote:Qr Bbpost How many cubic inches is the engine, how many rpm is it running at runaway, how much does the bottle hold, and finally, if the engine is still spinning when you run out of suppressant, it may light off again and off it goes.

Ok, so you went and made me do some math!!! A typical small boat FM-200 system would get sucked though his engine in 3-6 seconds at 6000 RPM... so you'd probably need a much larger unit to make sure it was effective. A block-off throttle sounds like an easier solution.

Not to derail this thread, but do regular marine diesels have such a device?

Viper can probably better answer that. I know of one for sure that did not!

If a single VW 4 popper with an out drive starts to run away due to a turbo oil seal leak (odds against it), maybe popping the drive into neutral would be a much easier, cheaper and less damaging option?

I don't think I've seen an OEM production air cutoff device. Engineers never believe anything will go wrong with their designs though. A runaway isn't a very common occurrence but when it happens, look out. Putting it in neutral won't do it, you want to suddenly load it in hopes of stalling the engine. Any electrical device to cut off air isn't the way to go IMO. It may not get used for years and as a result fail when you really need it. A mechanically actuated system with a cable I think is best but preventing the engine from ingesting air is about the only sure way to do it providing the air intake circuit doesn't have a break in it somewhere that will continue to let air in. You can use a CO2 fire extinguisher aimed at the intake to replace the oxygen and prevent combustion as long as you have enough of it. The turbo isn't the only potential cause, any oil leaking into the air intake stream will cause the same thing such as blow by. Other external sources in the engine room such as an oil leak spraying in the right direction will do it.

There's a few things you can try to stop a runaway but in a case where you have to crawl into a cramped engine compartment to do anything, it can be downright life threatening. If it gets bad enough, the forces are incredible and the engine can literally explode. You don't want to be around when that happens.

To give you an idea of an engine grenading.....

https://www.youtube.com/watch?v=d_8Fc9qAZcw

I belive it was in 1998 that vw took care of the issue of a run away diesel, in the programming of the electronically controlled engine. When dropped back to idle run away or not it will keep it 1200 rpms. I will be running and brand new (not china knock off) turbo so hopefully bearing seal failure or excessive blow by wont be an issue for me anyway!

That is if the ASV is functioning property. There is a manual way to activate it, I'll look it up