Runaway Engine

[gpd955]

Is anyone familiar with runaway engine with regard to degrees of heel. I understand the concept with excess oil but never heard of it when it comes to heel (until this week). The last boat had an Atomic 4 and this is the first diesel I've owned. I've motorsailed other friend's boats and they never mentioned it as a concern.

 

[kloudie1]

Never heard of that as a problem.. With an outboard, the prop can come out of the water and cause that but it is unlikely on a diesel inboard.. Good luck with teh boat, Jack !

 

[Billbeard]

I don’t know much about diesel engines. But it is my understanding that a diesel that is hot and whose oil has become no longer viscous can on occasion run away that is start burning its own lubricant which can be very difficult to stop once the process has begun. This will generally run the engine beyond its rpm. Capability’s ending with the engine destroying itself.

 

[Bill Roosa]

Heel and using the engine

I understand that heel will effect the ability of an engine to obtain lube oil from the sump. Also understand that an engine with bad oil rings can run on it's own lube oil. I don't understand how a heeled engine could get into the situation where lube oil would enter the combustion chamber and still have lube oil being supplied to the engine. I'd think that IF that happened the engine would seize before the oil getting to the combustion chamber. It would have to be heeled over beyond 90 degrees to have oil enter the bottom of the cylinder. I can't really see that happening in practice.
If you where heeled that much you could be sailing at hull speed so why even have the engine on?

 

[Ross]

Re: Heel and using the engine

Worn engines may runaway but it is rare. A runaway engine has an uncontroled source of fuel usually from worn rings. Choking the air intake is the only way to shut it down.

 

[SamLust]

Excessive heel can cause oil to slosh up against pistons, getting by rings. Do not confuse outboard over revving because prop is no longer under load because it has lifted out of the water with a runaway diesel which is running out of control on it's own lube oil. Most 4 stroke outboards now have over-rev limiting protection now.

 

[Don12364]

I Worry About

I worry because nowadays engines, in order to be 'green', now duct their crankcase gasses into the air inlet filter, albeit through a nominal pressure relief valve.
To me this means any overfilled engine or one with combustion gasses leaking past its piston rings has the propensity to run on its own engine oil.
Air filters can be rotated and I have set mine up so that, in the case of a runaway, I could put my hand over the air inlet spout - though whether I would dare to do so is doubtful. I think my palm could withstand 15 PSI vacuum over a 1½" diameter.

For Info: My pal was a boat salesman and it was the day of his new customer to accept his new boat.
He had previously just motored the boat to its berth.
He started the engine to demonstrate it and slowly the revs began to increase.
He shut the throttle but the engine speed continued to increase.
He pulled the 'Stop' control without effect.
He put it into gear but the revs continued to build. They reached 4000 RPM.
He went below and operated the 'Stop' control at the engine, suspecting it might have become disconnected from the wire above. It was connected.

All this took a couple of minutes. The revs kept rising despite being in gear. By now clouds of blue smoke were billowing from the exhaust.
The revs went off the clock, they think to 7,000.
He felt he could do nothing so recommended they both got off the boat - quickly.
He then went in search of the yard's engineer.

Suddenly everything went quiet.
Seized solid.
This all took about 4 minutes - so, if it happens to you, there is time to react - provided you realize that it is happening and act immediately.

Not exactly a good start for a brand new boat!
A new engine was supplied to replace the previous one.

The subsequent post-mortem revealed the sump had been considerably over-filled with oil.

 

[threehulls]

Re: I Worry About

I had a runaway experience with my Yanmar 2GM diesel in my trimaran about 6 weeks ago. Heeling was not an issue. The engine is about 10 years old but has only done 400 or so hours and has never let us down. We set off from the dock motoring at about 2800 rpm (3600 is max). After only 10 minutes the engine speed increased and clouds of white smoke appeared out of the exhaust. I have much diesel experience so I guessed what was happening. Even so I first pulled the stop control to no avail. Then I reduced throttle but of course that took it out of gear and made the situation worse. The boat did not seem to be going any faster so I suspect major prop cavitation at the higher engine speed. Then I did the unthinkable and slammed it back into gear. I thought the transmission was going to jump out of the boat. To an engineer, the noise was much worse than that I heard many times when teaching my daughter to drive a stick shift! The engine finally slowed down and came back under control of the throttle. We slowly motored back to the dock. I found that the oil level was way over the full marl. The mechanical lift pump had been leaking fuel into the crankcase. Under the right conditions, this volatile mixture was getting into the intake manifold via the breather tube. Luckily the engine has performed flawlessly since. My guess is it ran at about 5000 rpm for 90 seconds.
Moral of the story, check the oil level EVERY time you go out.

 

[FastOlson]

Is anyone familiar with runaway engine with regard to degrees of heel. I understand the concept with excess oil but never heard of it when it comes to heel (until this week). The last boat had an Atomic 4 and this is the first diesel I've owned. I've motorsailed other friend's boats and they never mentioned it as a concern.

Some clarification is needed...
An "Atomic 4" engine is by definition a gasoline engine. The runaway engine thread addressed in some replies would apply to a diesel engine.
In any case, the problem is extremely rare. Usual fix, if you work fast, is to cut off the air supply -- put something over the air intake (but NOT your hand!).
Without air the diesel will instantly stop.

Regards,
L

 

[gpd955]

I have a Universal M25XPB now, the A4 was in my Catalina 30. When I had this boat surveyed, the discussion of the runaway engine came up and I jusst wanted to figure out how accurate the "runaway engine due to >10 degree heel" claim that he made was. None of the diesel owners that I know ever heard of it outside of the overfilling cause and since I have little experience with diesels (except helping friends out with theirs) I wanted to get some more expert opinions. The bulk of my delivery is going to be on Friday/Saturday and I expect to motorsail some of the way. Just want to make sure I don't kill this engine. Had enough issues with the A4 to last a lifetime!

Thanks for all of the input!!

 

[Stu Jackson]

You have a great engine. In 12 years I have not heard of any of these issues with 1800 C34s, 6,000 C30s, 2100 C36s and the Ericsons. While the M25XP engines were made until the early 90s, I think, their successors, the M30 and M35 series are essentially big brothers to the same design concept.

You don't get it form heeling. These posts prove that and also explain why to check your oil level every time, not just sometimes. You already know about our C34 website's engine database for your puppy.

 

[Steve Dion]

I suggest that you contact Universal. They probably have some engineering specs that dictate the max degrees of heel.

I do not think you will have any problems up to about 15-20 deg of heel unless there is something wrong with the engine.

I think that this may have been an issue on some of those older Yanmar's that were mounted on their side. One of the owners in our marina experienced this once or twice.

 

[shorty]

At the Mack Boring Day with Your Diesel, Larry Berlin says to not run engine @ anything greater than 15d heel. Otherwise problems picking up oil from sump & fried engine possible.

 

[Ross]

Most engine have limits on running position. Bulldozers can damage the engine if they are run for too long on very steep grades.

 

[druid]

Both the Universal M25 and the Yanmar 2GM series have decompression levers - why not use them to stop the engine? It's easier than finding a rag, and I can't see a diesel running without compression...

As for the OP - I suppose if there's ENOUGH heel, the oil in the crankcase might run up the cyl and get by the rings, but we're talking over 45 degrees...

druid

 

[rejenk3]

At the power plant I worked at we had CO2 injectors on the standby diesels, for run-away prevention. May not be a bad idea to have a CO2 extinguisher mounted close to the engine.

 

[Snotter]

I wonder if a halogen engineroom extinguisher would work for this purpose. Regardless, the previous post has got me thinking of rigging a way to manual set off an engine room extinguisher from the cockpit.

 

[Bill Roosa]

Halogen will work fine

Anything that robs the engine of oxygen and is a gas. Dry extinguishers would work too but you would ruin the engine using it as it would be stopping the engine by making all the parts sandpaper.
CNG would work as long as it does not mix with O2. Course I'd not recommend that to anyone but you get the idea.

 

[rejenk3]

The plant (nuclear) used Halon fire suppression in the control room. so the operators could remain on station. It's leaves a breathable mixture but interfers with combustion. Its not oxygen displacing, so it may or may not work on a compression ignition engine. But CO2 or N2 would definitely work. Obviously, after using an oxygen displacing gas, you would want to immediately evacuate the cabin until it's thoroughly vented.