Engine seems to start but rolls to a stop

[GrowleyMonster]

Originally Posted by JustinT

Well, I'm struggling to work out how to do the gravity tank. My pipes are mostly metal with banjo fittings at the end.
Then I keep looking at the fuel coming out the check valve on the fuel filter and the pulsing fuel from the injector pipes.
On trying the engine it is so running until I let go of the key/cranking.

I have loosened the cylinder cover to rule out the compression holding the rockers.
I have wound out the solenoid so it's in no way stopping the running.

You are going to have to be a problem solver, and innovate. If you need a banjo fitting to connect to your injection pump, then get one or make one. If all of the points where a banjo is used are the same size, you have only to make or acquire one of them, to be able to insert fuel at any point in the system with your gravity feed ad hoc fuel tank.

If you don't somehow split up the system and isolate parts of it, then the only sure way for you to find the problem is to one at a time, replace each and every component until it finally runs.

[Wotname]

Originally Posted by deblen

https://youtube.com/shorts/6lqyWVqTJ...vIhPQqf5JAR7hi


Guys. Do you think there is enough valve clearance?
Are the valves seating?
Is there compression enough?

All good questions. Obviously the best option is to measure the compression but I'm assuming JustinT does not have access to a compression gauge or even a ready source to buy one.

If it was me, I would fill a small spray bottle (spritz sprayer) with a mix of diesel with 5 to 10% of petrol (gasoline) and spray that lightly into the intake manifold while cranking the engine. A kind of poor man's engine start spray. If it fires and keeps on firing while spraying, then compression is probably borderline low. Once the combustion chamber gets hot enough and assuming the injectors are working properly, the engine should be self sustaining (running) even with marginal compression.

[GrowleyMonster]

Originally Posted by deblen

https://youtube.com/shorts/6lqyWVqTJ...vIhPQqf5JAR7hi


Guys. Do you think there is enough valve clearance?
Are the valves seating?
Is there compression enough?

What is your measured clearance? If it is within specifications then it is good. You measure clearance by seeing which feeler gauge slips through with resistance, but light resistance. Follow the procedure. When the cam for the valve being checked is at the bottom of its rotation, and the gap is at it's greatest, is the point of engine rotation when you check it. We can see that the valves are operating but we cannot see if the valve ends of the rocker arms are high enough to let the valve seat properly and for the proper duration.

Simply being close should let your engine start. But if the gap is too close, the valve will be held down longer than optimum. If the gap is too great, then the valve will be closed longer than optimum. Either condition will keep your engine from running PROPERLY, and eventually maybe damage your engine.

If there is any doubt, check them again, but first review the valve adjustment procedure in your manual and also on youtube. If the gap is in spec, then it is in spec. If you want to know if your valves are seated well, then remove an injector and connect your compression gauge and crank the engine with the starter. Repeat with the other cylinder. See of the readings match what is in the manual. The only way for us to really determine what your compression is, is for you to tell us. To do that, you must connect a compression gauge and crank the engine. Compression gauges are cheap. The only difficulty might be in finding an adapter that fits your injector port. For some engines they are hard to find and must be made out of an old injector or machined from stock.

Did you use a torque wrench to tighten the head bolts, and tighten them in the recommended order?

Remember that any valve operates once in every TWO revolutions of your engine.

I still think your main problem is fuel delivery. I could be wrong, but if it were my engine I would cheerfully bet a few hours of my time to prove it one way or the other, and find the part that isn't doing what it should or is doing what it shouldn't.

I hope by this time that you have found a Bukh owner/user forum or discussion group. Try Reddit. You may be able to find a compression gauge adapter to buy or borrow, if none that come with your gauge will fit. Other owners of the same engine are a tremendously valuable resource, especially for scarce parts and specialized tools.

[deblen]

Page H13 in manual-Hi Pressure fuel pump.
If you remove the inlet banjo fitting at HP pump & loosen the output banjo of the fuel filter(& then retighten)-could you move the filter to HP pump pipe enough to insert the HP end into a small container.
Then crank engine & check fuel flow.
Len

[JustinT]

Originally Posted by GrowleyMonster

What is your measured clearance? If it is within specifications then it is good. You measure clearance by seeing which feeler gauge slips through with resistance, but light resistance. Follow the procedure. When the cam for the valve being checked is at the bottom of its rotation, and the gap is at it's greatest, is the point of engine rotation when you check it. We can see that the valves are operating but we cannot see if the valve ends of the rocker arms are high enough to let the valve seat properly and for the proper duration.

Simply being close should let your engine start. But if the gap is too close, the valve will be held down longer than optimum. If the gap is too great, then the valve will be closed longer than optimum. Either condition will keep your engine from running PROPERLY, and eventually maybe damage your engine.

If there is any doubt, check them again, but first review the valve adjustment procedure in your manual and also on youtube. If the gap is in spec, then it is in spec. If you want to know if your valves are seated well, then remove an injector and connect your compression gauge and crank the engine with the starter. Repeat with the other cylinder. See of the readings match what is in the manual. The only way for us to really determine what your compression is, is for you to tell us. To do that, you must connect a compression gauge and crank the engine. Compression gauges are cheap. The only difficulty might be in finding an adapter that fits your injector port. For some engines they are hard to find and must be made out of an old injector or machined from stock.

Did you use a torque wrench to tighten the head bolts, and tighten them in the recommended order?

Remember that any valve operates once in every TWO revolutions of your engine.

I still think your main problem is fuel delivery. I could be wrong, but if it were my engine I would cheerfully bet a few hours of my time to prove it one way or the other, and find the part that isn't doing what it should or is doing what it shouldn't.

I hope by this time that you have found a Bukh owner/user forum or discussion group. Try Reddit. You may be able to find a compression gauge adapter to buy or borrow, if none that come with your gauge will fit. Other owners of the same engine are a tremendously valuable resource, especially for scarce parts and specialized tools.

My exhaust is 0.30mm and inlet 0.25
However, I was doing the gap when the engine was TDC
I'm also having a hard time working out when to adjust which valve as I don't think I adjust them all when the engine is TDC. Very confused and the YouTubes don't seem to help.
Another yacht owner here says he has a compression gauge and is searching it out for me.

I did torque the head blots in order and to the correct torque. Although I couldn't find the toque value for the cylinder cover, which seems significant due to the decompression levers.

[JustinT]

Originally Posted by Wotname

All good questions. Obviously the best option is to measure the compression but I'm assuming JustinT does not have access to a compression gauge or even a ready source to buy one.

If it was me, I would fill a small spray bottle (spritz sprayer) with a mix of diesel with 5 to 10% of petrol (gasoline) and spray that lightly into the intake manifold while cranking the engine. A kind of poor man's engine start spray. If it fires and keeps on firing while spraying, then compression is probably borderline low. Once the combustion chamber gets hot enough and assuming the injectors are working properly, the engine should be self sustaining (running) even with marginal compression.

Good point, I did mix some Spiritz but kept forgetting to give it a go.

[JustinT]

Originally Posted by deblen

Page H13 in manual-Hi Pressure fuel pump.
If you remove the inlet banjo fitting at HP pump & loosen the output banjo of the fuel filter(& then retighten)-could you move the filter to HP pump pipe enough to insert the HP end into a small container.
Then crank engine & check fuel flow.
Len

Thank you!

[jamhass]

I'm sure you've already figured this out, but for finding TDC to check the valve clearances:

Illustrations of the crankshaft in the workshop and parts manual clearly show that both pistons move up/down together. This makes finding the "right" TDC spot to check clearances easy.

Rotate the crank until one of the cylinders has one valve just moving up while the other is just moving down the same amount. This is TDC and the spot to check the OTHER cylinder's valve clearance. One turn of the crank and it's time to check the other pistons valves.

[JustinT]

Originally Posted by jamhass

I'm sure you've already figured this out, but for finding TDC to check the valve clearances:

Illustrations of the crankshaft in the workshop and parts manual clearly show that both pistons move up/down together. This makes finding the "right" TDC spot to check clearances easy.

Rotate the crank until one of the cylinders has one valve just moving up while the other is just moving down the same amount. This is TDC and the spot to check the OTHER cylinder's valve clearance. One turn of the crank and it's time to check the other pistons valves.

I see, thanks, I think I'm getting it now. I'm being very dense about this I realise.

[deblen]

How to check valve lash/adjustment/gap:
2 cyl BUKH DV20 with no external timing marks


1.Begin with Cyl. #1-the front cyl.
2.The larger valve is Intake-& is beside the air intake for that cyl.
the smaller is Exhaust & is beside the ehaust outlet for that cyl.
3.Roll engine by hand until both valves in that #1 cyl are closed. ie: fully up with no spring pressure against either.
4.If you roll a few more deg.,the intake rocker will move down & press on the intake valve stem.Roll back & the exhaust rocker will move down against exhaust valve stem. Roll to a point midway between these two.
5.Both rockers should now be loose. Insert appropriate feel gauge to each valve & adjust the rocker screw/locknut so that gauge can just be pulled out with slight drag/effort.

6.Roll engine by hand until both valves in cyl # 2 are closed & repeat same proceedure as cyl #1
That is it.
Cheers/Len

[JustinT]

Thank you

[GrowleyMonster]

Originally Posted by JustinT

My exhaust is 0.30mm and inlet 0.25
However, I was doing the gap when the engine was TDC
I'm also having a hard time working out when to adjust which valve as I don't think I adjust them all when the engine is TDC. Very confused and the YouTubes don't seem to help.
Another yacht owner here says he has a compression gauge and is searching it out for me.

I did torque the head blots in order and to the correct torque. Although I couldn't find the toque value for the cylinder cover, which seems significant due to the decompression levers.

I don't think you want to do both cylinders at the same time. Remember, in a cycle, there are TWO TDC points. I believe both pistons are at TDC at the same time, but one is at the end of the compression stroke / beginning of the power stroke, and the other is at the end of the exhaust stroke / beginning of the intake stroke. In other words, when both pistons are at TDC, one cylinder is firing with both valves closed, and the other is just doing housekeeping. At the next TDC, they are reversed. I got to think about this and read your manual. Remember, it is a four stroke engine. Up - down - up - down is two revolutions of the crankshaft but only one revolution of the camshaft. Before you do anything wait and see if someone more familiar with your engine will weigh in. Improper valve lash COULD result in another valve-piston collision, especially if you start with bad and make it worse.

<EDIT> deblen beat me to it and seems to be spot on the money with a good answer.

[GrowleyMonster]

Originally Posted by JustinT

My exhaust is 0.30mm and inlet 0.25
However, I was doing the gap when the engine was TDC
I'm also having a hard time working out when to adjust which valve as I don't think I adjust them all when the engine is TDC. Very confused and the YouTubes don't seem to help.
Another yacht owner here says he has a compression gauge and is searching it out for me.

I did torque the head blots in order and to the correct torque. Although I couldn't find the toque value for the cylinder cover, which seems significant due to the decompression levers.

Oh and the valve cover torque should have a specific torque listed, but it is not super critical. It is just to keep oil from slobbering out, mostly. Snug them down diametrically and just good and snug, and you should be good. The head bolt torque is somewhat critical, though. Improper or imbalanced torque can cause a blown gasket or even worse.

[JustinT]

Originally Posted by deblen

How to check valve lash/adjustment/gap:
2 cyl BUKH DV20 with no external timing marks


1.Begin with Cyl. #1-the front cyl.
2.The larger valve is Intake-& is beside the air intake for that cyl.
the smaller is Exhaust & is beside the ehaust outlet for that cyl.
3.Roll engine by hand until both valves in that #1 cyl are closed. ie: fully up with no spring pressure against either.
4.If you roll a few more deg.,the intake rocker will move down & press on the intake valve stem.Roll back & the exhaust rocker will move down against exhaust valve stem. Roll to a point midway between these two.
5.Both rockers should now be loose. Insert appropriate feel gauge to each valve & adjust the rocker screw/locknut so that gauge can just be pulled out with slight drag/effort.

6.Roll engine by hand until both valves in cyl # 2 are closed & repeat same proceedure as cyl #1
That is it.
Cheers/Len

So on this forum:
https://forums.ybw.com/threads/bukh-...arence.555977/

They are saying get the exhaust valve right TDC on one cylinder then rotate the engine right around to TDC again and do the inlet on that cylinder. Then onto cylinder 2.

The more I look at it the more confused I get.

[GrowleyMonster]

Originally Posted by JustinT

So on this forum:
https://forums.ybw.com/threads/bukh-...arence.555977/

They are saying get the exhaust valve right TDC on one cylinder then rotate the engine right around to TDC again and do the inlet on that cylinder. Then onto cylinder 2.

The more I look at it the more confused I get.

I suggest you stick with Deb's directions at this point. They are very clear and to the point, and will be easier for you to follow.