Runaway Diesel

[seashine]

Wow! I've read about this and have a kill switch and reasonably quick access to the fuel shutoff but running on oil sounds s-c-a-r-y!!

[seashine]

Originally Posted by seashine

Wow! I've read about this and have a kill switch and reasonably quick access to the fuel shutoff but running on oil sounds s-c-a-r-y!!

P.S: a very helpful post, so glad the hand's functional ~ we humans are an important bit of kit for running a boat ;-)

[hmeilman]

Originally Posted by seashine

P.S: a very helpful post, so glad the hand's functional ~ we humans are an important bit of kit for running a boat ;-)

Had a 375 HP 3208 CAT run away when an injector line broke under the manifold cover. Fortunately it self extinguished when the engine room filled with smoke. Shut the other engine down too. Hot oil sprayed everywhere. If it happens again I would activate the engine room fire suppression system to starve it. Best advice from old time mechanic was to get north or south of engine in case parts start flying out. One of The scariest moments I've had on a boat.

[ValiantV]

Originally Posted by DumnMad

Fuel shut-off would be my 1st reaction but if its oil burning that would be no use.

Kinda curious about that myself.

I would figure if killing the fuel supply by loosening all of the injector lines stopped the engine, it probably wasn't running off of it's crankcase oil - though that is the "classic" cause of a runaway diesel.

Never knew it was so common that we'd get so many stories of witnessing it!

I used to work on GM cars when they first dabbled with diesels in passenger vehicles. (About 1980 I think) The open intake of a 350 cubic inch (5.7 litre) diesel engine revved even to normal speeds is nothing you'd want to put your hand near. I can't imagine the din of one turning anywhere near redline.

Having worked in a shop with an engine dynamometer, standing anywhere near a full-size, high-performance V8 putting out near rated horsepower at high RPM will send most folks edging nervously for the nearest exit.

Anyway, thanks for one more item for my "things that can happen on a sailboat that will pretty much ruin your whole day" list.

[rbk]

It’s always been my understanding that a run away is specifically referring to running off the crank case fluids, whether straight oil but more likely a mixture of oil and diesel. Is there a case where a diesel can runaway from the fuel being supplied via the IP?

[zeehag]

fuel shut off didnot work. as long as there is oil in the engine, there is fuel. got to make oil no longer an issue.
you MUST kill the engine by use of removal of all that makes diesels run and introducing that which makes diesels stop running. as it is difficult to remove oil flow, easy to remove fuel flow, and easy to introduce air into engine to stop it, we did that. took less than 5 min, during which time the freight train ran over the erector set town more than once. damages inside engine were impressive ..i have never destroyed an engine that well, and i have tried hard.
those ways are obstruct air intake or introduce air into machine. introducing air while shutting off fuel forceably was our method..crack injectors. yes i have wrench in appropriate location., painted the correct color for identification.

as for the noise??? holy ***** mon... impressive, but no crunching or banging..just hellahigh rpms. and ever increasing as we stilled the beast
and SMOKE!!! only color smoke we didnot have was pink
yes runaway diesel is an impressive experience.

my issues began with lift pump fail an d fuel in crankcase and progressed to fail injector pump. there was no lipping of pistons nor scoring of cylinders--was fuel delivery initiated.

[RoryD]

What does ‘crack the injectors’ mean?

[zeehag]

Originally Posted by RoryD

What does ‘crack the injectors’ mean?

crack em open. open em..bust em loose.. open em up.. let lots of air into the injectors to prevent fuel flow

[RoryD]

Thanks.

[Wotname]

Originally Posted by rbk

It’s always been my understanding that a run away is specifically referring to running off the crank case fluids, whether straight oil but more likely a mixture of oil and diesel. Is there a case where a diesel can runaway from the fuel being supplied via the IP?

In the case mentioned in post #21, the original fault was the governor had been accidentally and unknowingly disconnected from the IP which forced the IP to full fuel flow mode. All the first stage safety devices relied on controlling the governor but as that was no longer connected to the IP, they had zero effect. Second stage safety mode controlled the IP mechanically but once again due to the "problem", these also were ineffectual. Third stage was fuel shutoff but by the time this was activated, the turbo seals had blown so the engine was pumping it's own oil past the turbo seals into the engine.

It was later estimated that some 20+ gallons of oil was consumed before it threw some rods.

[Jim Cate]

Originally Posted by Wotname

In the case mentioned in post #21, the original fault was the governor had been accidentally and unknowingly disconnected from the IP which forced the IP to full fuel flow mode. All the first stage safety devices relied on controlling the governor but as that was no longer connected to the IP, they had zero effect. Second stage safety mode controlled the IP mechanically but once again due to the "problem", these also were ineffectual. Third stage was fuel shutoff but by the time this was activated, the turbo seals had blown so the engine was pumping it's own oil past the turbo seals into the engine.

It was later estimated that some 20+ gallons of oil was consumed before it threw some rods.

In all these scary stories, I'm surprised that valve float didn't limit the revs somewhat. Engines designed to run at slow speeds usually have pretty weak valve springs. Or maybe the float wasn't severe enough to limit unloaded RPM, I dunno... just thinking back to my drag racing engines from years ago, but those engines were surely not "unloaded"!

Jim

[Cormorant]

I'm wondering if the risk of runaway diesel (consuming engine oil) would be mitigated at all by use of full synthetic oil with its higher flash point.

Do you all run synthetic anyway, or conventional mineral based engine oil?

[Pete7]

Originally Posted by Cormorant

I'm wondering if the risk of runaway diesel (consuming engine oil) would be mitigated at all by use of full synthetic oil with its higher flash point.

Do you all run synthetic anyway, or conventional mineral based engine oil?

Given, the number of videos on you tube of run away engines some in newish cars, I don't think it matters.

Still think it would be a brave person to crawl into a yacht engine space and start fiddling with the injectors when the engine is running away. Perhaps someone could take a camera and film it as it happens, especially the bit were the con rod comes through the block.

Pete

[zeehag]

Originally Posted by Pete7

Given, the number of videos on you tube of run away engines some in newish cars, I don't think it matters.

Still think it would be a brave person to crawl into a yacht engine space and start fiddling with the injectors when the engine is running away. Perhaps someone could take a camera and film it as it happens, especially the bit were the con rod comes through the block.

Pete

my engine space is huge and nonconfined once ye throw off the easily tossed dinette seat, injectors are immediately presented .. liike right there.. easy access. easier than fiddling about with an air cleaner.
when the issue was all injector pump and governor related it seemed the best and quickest thing to do . we didnot hole block nor send pistons shooting thru hull or any other spek ~tacular things besides helluvalotta smoke of all colors except pink and purpul.

y'all forget i have formosa41, designed to cruise trade winds therefore easy access to alll working parts while underway. one of the few sensibly built boats i have encountered since 1955. fiddling?? hell the wrench is immediately accessible as well, so all is right there.

[Pete7]

Originally Posted by RoryD

What does ‘crack the injectors’ mean?

Good luck to finding an air filter or the injectors.

https://www.youtube.com/watch?v=5zx3qKX_Pno