View Full Version : Uncontrolled engine speed Bukh DV20 marine engine intermittent problem

03-06-2003, 08:22 PM
" I have an unusual problem with a Bukh DV20 marine engine - the engine periodically & without warning will "run away" ie; reach destructive speeds from a low idle speed setting to 4000+ rpm leading to destructive engine damage. This has happened on 2 occasions & on both occurences the engine had been idling under a no-load condition @ approximately 1000 rpm.The engine had to be reconditioned after the first event as it dropped an exhaust valve @ destroyed the piston, damaged the head,etc.While the engine was out of the boat I thoroughly inspected the governor & could find no evidence of a problem @ all.The fuel injection pump & injectors were both reconditioned & calibrated & the governor was set for correct low speed settings as per the manual, on the engine test stand subsequent to the overhaul.The engine starts & runs flawlessly under all conditions & even when it runs away it shows no sign of excess smoke on the exhaust. It doesn't burn oil & the oil is changed @ 50 hr intervals, using SAE 15w40 CG4 classification oil.I am an experienced diesel engine mechanic with 28 years of experience in the heavy equipment & marine industries & admit that this one has me baffled. I have even considered the possibility that the engine is running away on it's own crankcase fumes but can find no evidence to support this theory.I did once encounter a precombustion chamber that ran away with a stuck fuel injector as the fuel @ transfer pump pressure was entering the precombustion chamber & burning uncontrolled-the governor cannot regulate what it does not deliver. If anyone can share their thoughts on what might be wrong here I would be most appreciative. "

03-07-2003, 12:09 PM
" Peter,

I have some thoughts on what the problem might be, but I am not that good at typing! I will email you my phone number and you could give me a call. I don't know where you are, I am in Connecticut.

Gil Plumb "

03-07-2003, 07:36 PM
" Gil, please share your thoughts even though it may be painfull for you to type. I have a diesel in my boat and am always trying to expand my knowledge, as I am sure others are too. Kim "

03-08-2003, 06:44 PM
" Kim,

I have to admit that I entered the above post for Gil. I had sent him the question by email and he told me he had some ideas for Peter.

Gil has a wealth of knowledge on gas and diesel inboards, but I understated it in my "stealth" post for him by saying that he is "not that good at typing".... the truth is that he will not even sit down in front of the computer! His wife prints out email and gives it to him. He is 77 years old and very active mentally and physically, but not interested in learning about computers.

If Peter calls him and gets some useful feedback I hope he will post it here for our mutual benefit.

Andrew "

03-09-2003, 06:38 PM
"Peter and Kim,

Since today is Sunday I thought I would post the following:

<CENTER>Ten Commandments of Diesel Engine Maintenance</CENTER>
I don&#39;t know how well it will display, the copy I have is 3rd or 4th generation...


03-09-2003, 08:02 PM
" I love it, Thanks, Kim "

03-11-2003, 08:47 PM
" Many thanks to Gil for a most informative &amp; interesting discussion this past Sunday on the problem I posted with the DV20 Bukh engine.After some lengthy discussion on the background history of this problem &amp; discussion of the unusual &amp; impractical method by which Bukh vents the crankcase fumes in this engine we both concluded that it may in fact be &#34;running away&#34; on its&#39; own crankcase fumes after extended periods of low idle operation.The crankcase vent in this engine exhausts directly into the intake manifold &amp; if the engine were to pull oil into the cylinders from this area it would be unable to regulate engine speed by the governor as the fuel source is not the fuel injection pump. I have witnessed a Cummins 6BT5.9 engine run away after a turbocharger failure on the compressor side that flooded the intake manifold with oil from the centre housing bearing section. The turbo was replaced on this engine but the manifold had not been removed &amp; cleaned of the engine oil residue &amp; on start-up the engine ran away to destruction-the engine would not shut down via the governor as diesel fuel being injected was not the primary source of combustion fuel.Diesel engines operate on the compression ignition principle &amp; the heat of compressed air to provide the source of ignition.If a fuel source enters the combustion chamber that&#39;s delivery is not regulated then there is no way to regulate engine speed.In light of this I will persue this angle &amp; provide an alternative source to vent the crankcase fumes, as well as remove the injectors once again &amp; verify that they are in fact OK.If anyone out there has anything further to share on this I certainly would be very glad to hear from you.
Peter "

03-11-2003, 09:33 PM
" Thanks for posting the followup Peter.
Good luck! Let us know what happens.
Andrew "

Carol Jacobsen
03-27-2004, 10:10 AM
" I loved the 10 commandments, I&#39;m a narrowboat owner in England with a Bukh engine and gearbox, the engine is fine, its the gearbox thats giving me problems.. so I&#39;m seeking anything I can about how to fix it. I&#39;ve had the engine apart and back together and thats fine.. but the gearbox jumps out of gear and refused to get in at all on some occasions. I need parts and any diagrams or manual etc, in fact anything that could help me fix it.. who said women cant be practical. I have a bet on with a guy who owns a traction engine, if I can get my boat up and running so&#39;s he can have it for a week, I can have the use of his traction engine for a weekend. Any help out there? "

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03-06-2006, 04:05 PM
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07-01-2010, 08:21 PM
Although somewhat dated, my son had a similar experience with a VW diesel engine. The cause was too much oil in the crankcase that became the unwanted fuel supply.

02-13-2011, 05:13 AM
Hi, Peter, I have worked with several different engines and it is very unlikely that the engine is running on it's own oil. When that happened how did you stop it. the only way you would be able to stop it is by cutting off the air supply. If that is the case an other reason could be trapped air in your governor. Are you able to disconnect the linkage from the governor and control the speed that way. Always keep the air cut off ready to trip to stop a run away engine. If you can control the speed that way it is the governor and if it still runs away then you can suspect other things. I do not know the type of engine you are working but if there is no rack that you can control the speed with it the problem will be in the governor. Check to see if low governor oil pressure causes the speed to increase or high pressure causes the governor to speed up. If it is low pressure, then you might have blockage in the supply line to your governor. Hope my little knowledge on your engine will help you. Im thinking that you have a metering jet in the governor and the engine starts at full trottle and when the engine starts the pressure increases to set it to the idle speed. With a blockage you will have low oil pressure and the engine will speed up. Wayne