Runaway diesel engines

[skipperpete]

Yes indeed Briis, that’s a lot of smoke. In the long history of Diesel engines and governors there’s been quiet times and busy times with overspeeds, a lot happened because of the design of the injector pump elements, if one stuck, they all remained in the ungoverned mode and went to overspeed.... most common on GM Detroit 2 stroke engines which had an intake flap built in specifically to stop this........ and then the CAV distributor pump became popular and the “ stuck rack runaway diminished substantially with all the new types of single element rotary pumps. Peace at last with most small engines for a while, then came turbocharged common rail engines and we were off to the races again with an entirely different way to destroy an engine ..... wastegates , broken turbo shafts and failed shaft seals and bearings, now very common and spectacular as in your video.

[deblen]

It would not be too complicated to build your own manual damper in many cases


https://www.amazon.ca/Stainless-Manu...0CF1W6Q4D?th=1

[Pete7]

Originally Posted by deblen

It would not be too complicated to build your own manual damper in many cases


https://www.amazon.ca/Stainless-Manu...0CF1W6Q4D?th=1

I suspect if you slam shut one of those valves on a run away diesel it will turn into a pretzel and be swallowed down the air intake. I was given one for a previous boat with a Ford 4.2L Dover engine. However, there is a risk that you could do even more damage so never fitted it.

Originally Posted by Briis

so I could put my hand or smaller rag on the main air-intake manifold pipe below to kill the engine immediately and effectively via air-starvation.

I am concerned about this advice and hope no one will try an put a hand anywhere near the air intake of a run away diesel. There is the potential for very serious injury.

Pete

[deblen]

https://thedrainagesource.com/valter...s-paddle-each/

[skipperpete]

I wouldn’t like to see anyone try to stop a true runaway with their hand and its certainly possible that a large enough diameter choker valve could be destroyed by the suction ( no more than -14.7 psi regardless of rpm) but from personal experience with the emergency shutdown on a GM 16V71 this doesn’t seem to happen in reality although they try very hard to stay alive and chuck out lots of smoke.
A correction re D Horizon, it did have a Simrad IACS fitted to each engine but the intake shutoff was manually operated and I for one would not like to operate that shutdown on a 7 megawatt Wartsïla engine … and only one engine is definitely established as being the culprit runaway.

[Jim Cate]

Originally Posted by Briis

Good chance you can get it close to plane. In runaway it'll make around 5-10X the power written on paper. It's almost the NOS of diesels, hence if you have 50 HP engine it can be 500 HP engine in runaway mode. Not sure the prop shaft, gearbox and the supporting bearings can take it though

I find the above to hard to believe. Having spent much of my early life desperately trying to get more HP out of engines, realizing a X10 increment seems wildly improbable. The limiting factors would be the max airflow that can be obtained through the intake passages and valve float at high RPMs.

Runaway engines are a scary phenomenon for sure but hyperbole ain't justified whilst discussing them.

Jim

[skipperpete]

Len, that blade valve link is well worth a look and it seems possible that the air cleaner and crankcase ventilation could go on the upwind side of the valve. The stumbling block here is that on our engines in yachts, overall the number of overspeeds is relatively low so it would be hard to justify installing that interesting valve...... and would have unknown success with any of the Shibaura derivatives, they have an internal gallery/ passage from the crank case to the intake manifold.... it is very small though??? And it would certainly create a low pressure in the crankcase.

[Tin Tin]

The OP may have seen this already in another post, I repost it here as it seems relevant

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

[skipperpete]

Thanks TinTin, thats an awful end to a very nice boat and a painful ordeal for the owner, I’m glad no one got injured. The problem is that they never found out why it happened, thats a Perkins engine in the pics and the injector pump ( DPA distributor or bosch VE if its a 4-154) on that engine is not prone to causing overspeeds so I’m none the wiser about why a happy healthy Perkins would run to destruction and sink the boat in flames. There was something odd about how the throttle cable ( or gear cable) got suddenly tight to move when going back to idle and then the engine raced away….. we’ll never know for sure.

[Compass790]

Skipperpete I can tell you that if you install the oil breather plate upside down on YS series Yanmar they will runaway if heeled. I used to sell aftermarket parts for them & at least 2 customers had this happen. I did warn warn those who bought pistons & liners about it.

Re: YANMAR RUNAWAY! Lessons Learned...
I had a runaway once with my Yanmar YSM 12... the oil breather plate had somehow been installed upside down, by a friend mechanic who had repaired the engine for some other reason which escapes me now, but I took the boat out on a solo sail one Tuesday morning in the False Bay area off Simonstown in South Africa, and unbeknownst to me the SA Navy restricted this bay during naval operations every Tuesday!! and they were having missile training!

Well I was trying to get out of their way and was sailing hard pressed to windward, well heeled over and had the engine running for extra speed.... what happened next was an absolute nightmare for any sailor, solo or otherwise!

Suddenly my faithful, reliable engine shot up to maximum revs and I could NOT stop her, and at this stage I had left the helm, and was down below panicking and clawing and pulling cables to stop her and just did not know what to do..

The naval frigate I had been trying to avoid was a couple hundred yards off my starboard bow and I knew those had not been friendly waves the white clad officers were executing...! The engine continued to scream out of control and I suddenly recalled reading once about this ugly phenomena, and how to stop them from running away, which was to starve them of air. I was able to grab a settee cushion and stuffed it onto the air intake, slowly the revs came down and finally petered out.... I later found out that the engine had been feeding on her own sump oil!!! and this was how I figured out the oil screen plate had been put back upside down and had been triggered by my heeling over when beating upwind...and I was severely reprimanded by the yacht club Commodore.


You can stop those little 8/12hp ys Yammers putting your hand over air intake BUT dont try it on a bigger turbo motor. Dont ask me how I know!

[skipperpete]

Yeah Compass, it all depends on the diameter of the intake, I actually do it quite often but can’t recommend it to forum members for safety reasons. The best strategy is to be prepared in advance like the old saying “hope for the best, prepare for the worst”. Its easy to crack open a few or all the injector pipes and spin the engine over , if there is good fuel delivery outta those pipes and pulling the stop control doesn’t change that delivery….. you have a potential runaway. I replaced a GM series yanmar after a backyard type marina mechanic refitted an injector pump but missed the yoke with the rack pin…. That little Yanmar threw the governor weights through the timing cover and it was finally halted by the desperate mechanic cutting off the fuel hose at the injector pump…… the engine was a “parts only” proposition after that.

[Compass790]

Do you have success with turbos blocking air intake by hand? I know you did say it depends on intake dia. but just am unsure if that includes turbos? I'm a backyard mechanic so dont have your experience with multiple motors.

I agree that you have to consider safety, American posters could be sued at the drop of a hat I guess.
I did say about dont try it on turbos as once I tried to stop a CAT front end loader ( about 1980 so details sketchy frm memory ) by putting hand over air intake & I was worried my hand was gunna disappear down it before a Rubber cap on the alternative air intake got sucked into the engine. Red ring was emblazoned on my hand matching air intake dia. Think I used something else over both intakes but this was an idling engine NOT a runaway.

[Pauls]

I had a runaway on an old GM 71 series engine. The cause was a jammed injector, on these engines one jammed injector jammed them all. I put a piece of wood over the air cleaner intake, it did not stop the engine (there must have been air leaks that provided enough air to keep it running, but it did slow it down to an acceptable RPM, and valving off the diesel stopped it in a minute or so. The engine was not damaged.

As was mentioned above, GM diesels from this era had air cut off valves built into the air cleaner. Simple and effective. I think adding this to modern diesels, especially turbo'd ones, is a prudent safety measure, especially on engines where reaching the air intake is difficult. If the air cleaner housing can take 14.7 psi then this can work. If the intake is easy to reach then just have something that can block the intake available. Anything used for blockage should be solid, ie wood, metal, etc. The suction from the engine will inhale rags, etc.

[skipperpete]

I’ve never tried choking a turbo compressor, a vacuum on the intake would cause a situation like compressor stall in reverse and that might not end well. It takes a very special type of courage to put a hand close to a fan spinning at 150,000 rpm. GM 2 strokes are the gold standard for heart stopping overspeeds. The old Hamilton island ferry “Quickcat” had two 16V92GM’s and one of em seized an injector entering the harbour…. An exciting moment for the engineer and the skipper, they knew the drill and kept the engine in gear until the engineer could get to the emergency shutdown and choke it.

[kryg]

impessive Video THANKS

Originally Posted by Briis

Just to illustrate my previous text on how much smoke and noise there is for those who haven't experienced a runaway diesel yet:

https://youtu.be/fJIcxMJevII?si=fDBlf3gp3DejtCvY