Engine seems to start but rolls to a stop

[JustinT]

One thing, first of all I'd left the oil feed to the rocker arms unplugged. Something squirted all over the cabin, but it wasn't gloopy oil. Looked more like oily water.... could it be the engine has water in it? Would that cause theses issues? I probably should drop the oil and put new oil in it.

[deblen]

Originally Posted by JustinT

One thing, first of all I'd left the oil feed to the rocker arms unplugged. Something squirted all over the cabin, but it wasn't gloopy oil. Looked more like oily water.... could it be the engine has water in it? Would that cause theses issues? I probably should drop the oil and put new oil in it.

Change oil before running because you probably knocked some sludge & other nasties loose while working on it. You could probably get by with the existing oil filter,for initial start up & brief run/test.
Then change oil & filter again before putting in permanent service.
Check oil for "graying" due to water contamination regularly for a few weeks.
Quick blackening of lube oil in a diesel is normal,due to soot,& indicates that the detergents in the oil are doing their job.


I may be wrong-not familiar with that engine-,but many engines have a "restriction" built into the rocker shaft lube pipe/system,to prevent spraying rocker oil all over the place.Rocker assemblies only need a trickle of oil.
Bukh-a,Bukh-a...
Len

[JustinT]

Thanks Len. Will give the oil a good check next visit to the yacht.

[deblen]

Originally Posted by GrowleyMonster

Youtube is your friend. Watch as many vids as you can stand. Also remember that even though both pistons on your engine are at TDC at the same time, (I believe, not a lot of hands-on with Bukh 2 cylinders) they are not both on the same stroke.

You don't adjust clearance when the cam is up and the valve is open. You adjust clearance when the cam is down all the way, and the valve is closed.There will be some gap or slack at that point. When the cam is up, the rod is pushing up on its end of the rocker arm, which is pushing the valve down against its spring, out of its seat and into the cylinder. At that point in the cycle, there is no gap to measure. If you follow exactly along with a good video you should be good to go.

Personally I have cheated on small engines as regards TDC vs valves open/closed.
One cyl. at a time & one valve in that cylinder.Put finger on rocker near adjusting nut.Hand roll engine until that rocker goes loose.Hand roll the engine a bit more-that tappet/follower is now on the lowest part of it's cam lobe.
Use feeler & adjust that loose rocker. Hand roll engine backwards a bit to start lifting that valve,then roll forward & re-check gap.
Repeat for rest of valves in engine.
Len

[JustinT]

Humm, I see, I'll try it as am not convinced of them at the moment.

[JustinT]

Today's frustration
https://youtube.com/shorts/dqHdS883e...dK7VShy5Ma7ej7
Regulator rolled back, solenoid loosened off

[deblen]

Congratulations!!

[JustinT]

Originally Posted by deblen

Congratulations!!

It doesn't stay running. Just up and putt putt putt stop.
However the putt putt putt is more enthusiastic even if it is still followed by an engine that does not run.



After compression it is very enthusiastic but then it is wild, followed by running down to a stop, like it always has done. Once I stop cranking the engine dies.

I wonder if the regulator is seized? Running out of ideas.

[deblen]

I listened to your video.
If this had been your first post,I think most would say-OH,that engine is not getting enough volume of fuel to the input of the injector pump.I is burning what little is in the line & slowly starving.The fuel supply is restricted somewhere-before the inj.pump.
Fact: You found stuck valves,rust,stuck tappet/follower/valve lifter,lot of old sludge in oil passages,etc.
You now have working valves,some compression,clear air inlet?,working injectors-proven by the engine running for a brief time in video.
If the engine injection pump has a steady,non restricted supply of fuel,The engine should keep running,at least as fast as video.
I don't know if you gave it any more throttle than the little bit in your video.One early post says he must give his DV20 1/3 throttle to get it started.
Yes-the governor/regulator could be stuck like several other things were. Research & check it for operation,if you can.


Then-I think you have to reset your mind back to the first 10-20 posts,where most of us were looking for poor fuel supply.
Note the precaution about turning raw water supply off so as not to flood with water while cranking.
I suppose the exhaust could be plugged enough to cause excessive exh. back pressure to build up-like putting a potato in a car exh.pipe
Remove the fuel pipe from the fuel lift pump(s) -check flow into a bottle,etc.
I will look at the fuel system & governor/injector system in service manual.
Cheers/Len

[deblen]

Section H Fuel System.
Check filter screen in lift pump.Bukh fuel lift pump filter.PNG Views: 15 Size: 198.0 KB ID: 289433" style="margin: 2px" />

[deblen]

Bukh Hi Pressure fuel pump- with throttle rack(s) pg H120? item d. & e.

Read the operation description of the HP pump.
The racks turn the fuel(throttle) control sleeve inside the pump.
Are the racks clean & free moving?
Is the mechanism in the engine free to move racks?
Sludg

Fuel pump with throttle(regulator) d. & e..PNG Views: 15 Size: 269.3 KB ID: 289436" style="margin: 2px" />

fuel pump throttle racks.PNG Views: 17 Size: 163.1 KB ID: 289437" style="margin: 2px" />e/rust in this area?

[JustinT]

Thank you so much Len. Here was me all out of ideas not able to sleep ar 2am. Your messages give me hope, plenty more to go ever again.

I'm actually not over water as the yacht is beached. The cooling worries me as the pickup is in a bucket of water. But it's not going down. Going to remove the impeller to do more tests.

Anyway, thanks again for your help, it's really very appreciated.

[Wotname]

OK, back to basics.

On the positive side - you know a shipload more about the engine than you did last year. You have overcome a lack of mechanical knowledge by asking questions and are now () listening to the answers. You have demonstrated you can learn new stuff. We all started off this way, none of us were born knowing how a diesel engine works. At this point you should be reading the manual over and over again during the 2am worry period. Initially the manual may seem hard to comprehend but as you learn more and keep reading, it becomes your best friend. It was written to to explain how everything goes together and how the engine works although it was written to an audience who has basic mechanical knowledge - which will be you soon! You have made the process of helping you easier by posting videos and responding to our collective input.

On the negative side - the engine isn't fixed, yet. There are more than one issue at play and until all are resolved, the engine won't perform as you need it to. You have to work through the issues one by one before the job is done.

My guess is the engine has been left unmaintained for a considerable period of time and now it is time 'to pay the piper'. Don't get despondent, the Bukh was well designed and is a tough engine to kill completely which is one of the reasons they were fitted to lifeboats.

The fact that it starts and runs for a short while tells me it is very fixable.

You need to get the cooling sorted before letting the engine run for too long as the cooling water is needed to keep the exhaust hose cool enough.

More later...

[Wotname]

Originally Posted by JustinT

One thing, first of all I'd left the oil feed to the rocker arms unplugged. Something squirted all over the cabin, but it wasn't gloopy oil. Looked more like oily water.... could it be the engine has water in it? Would that cause theses issues? I probably should drop the oil and put new oil in it.

Yes, you probably should but before that, please post a picture of the existing oil.

What colour is the oil on the dipstick?

a. almost clear (like new)
b. honey coloured
c. black
d. grey (like a milkshake)

a, b, c are all ok and you don't need to worry about an oil change ATM.

d is very problematic as it indicates oil has been contaminated with water. The water gets emulsified in the oil, turning it a grey colour.
Drain the oil and replace the oil filter.
Fill with the cheapest supermarket engine oil.
With the engine decompressed, seacock closed and fuel shut off, spin the engine over (using the starter motor) for 30 seconds.
Wait five minutes.
Spin it again for 30 seconds.
Wait five minutes.
Repeat this say 10 times unless the battery is getting too low. The 5 minute wait time is to ensure the starter motor doesn't overheat although with the engine decompressed, the load on the starter motor is not high.

The idea is to circulate good oil throughout the engine flushing out the contaminated oil.

Drain oil and replace filter again. Fill with good (diesel) oil and get back to getting the engine running .

[JustinT]

Thanks Wotty, I have a long list to take to the boat with me today