Bukh dv 24 flywheel bolt fail

Boater Sam said:
I would not trust that crankshaft with new bolts in it. There ir bad distortion around all the holes and as to what state the threads are in is another matter.
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The damage to the threads is restricted to the first two threads only, the crankshaft end face polished out well
 
europe172 said:
Yes, engine had run for about 1.5 hours about 20 mins idle and the rest at 3/4 throttle . I had not touched the flywheel since I had the engine.
The supplier is testing bolts urgently. The supplier uses these bolts for many engines each year and does not have this happen, as evidenced by their reputation. One possible explanation is that the flywheel was not properly seated during bolt installation ( the bolts are replaced as a routine item ) and shortly after running the flywheel seated causing the bolts to be loose
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How long have you had the engine? Often, as an aid to fittng, the flywheel is removed from the engine and then reattached when the engine is installed.. did this happen with yours?
I hope you have retained one of these bolts as 'evidence'. If recently supplied, is the supplier confirming that they will cover your costs? You might also consider opening a conversation with your insurer....
 
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RivalRedwing said:
How long have you had the engine? Often, as an aid to fittng, the flywheel is removed from the engine and then reattached when the engine is installed.. did this happen with yours?
I hope you have retained one of these bolts as 'evidence'. If recently supplied, is the supplier confirming that they will cover your costs? You might also consider opening a conversation with your insurer....
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New to me engine , I have no costs so far. I have kept the broken bits and I am in contact with the supplier who is advising
 
europe172 said:
The damage to the threads is restricted to the first two threads only, the crankshaft end face polished out well
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I think that I would echo Boater sam's comments above.
The crank looks to be severely damaged. Not only have you lost 15-25% of thread, the hole entrance is now oval allowing flexing of the bolts in that area in addition to the face of the crank looking like it has suffered severe abrasion. Unless you have access to some top line repair facility I think that I'd maybe want a new shaft there.....! You might also want to inspect the flywheel as it may be in a similar state.
 
Boater Sam said:
I would not trust that crankshaft with new bolts in it. There ir bad distortion around all the holes and as to what state the threads are in is another matter.
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The incident I referred to.in an earlier post was dealt with by replacing the bolts with the correct bolts and very carefully dressing the shaft with an.oil stone. No.more problems with the engine til the boat was unfortunately lost in The North Sea when it met an unlit container in the water. !
 
But they should be put in with Loktite so retorquing will destroy the adhesive! Check they are tight, yes, but if you get any movement withdraw, re Loktite and retorque. To be pedantic, you should then have fitted a new screw!
 
That is only true if they are stretch bolts and the manual requires it; the Bukh manual does not, so it's down to a judgement based on age, length of operation and physical condition.
 
I am very surprised by the condition of the surface of the crankshaft. What has caused that pattern of wear
 
Difficult to say, it may be mostly debris from the wear, while the flange face is important the biggest concern is the spigot that the flywheel locates on. Significant wear there would prevent accurately registering the flywheel to the crankshaft.
 
penfold said:
Difficult to say, it may be mostly debris from the wear, while the flange face is important the biggest concern is the spigot that the flywheel locates on. Significant wear there would prevent accurately registering the flywheel to the crankshaft.
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The engine ran today for 5 hours, sounds good, the face cleaned and polished well , so I am hopeful. Will recheck torque tomorrow ( without turning bolts)
 
penfold said:
Difficult to say, it may be mostly debris from the wear, while the flange face is important the biggest concern is the spigot that the flywheel locates on. Significant wear there would prevent accurately registering the flywheel to the crankshaft.
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If I didn't know better I would be tempted to think that the surface damage to the crank flange face was caused by rotary friction as if the flywheel had been rotating against it and the two surfaces had 'picked up' due to friction / heat. There is a degree of damage on the spigot circumference too which also looks like it was caused by rotation of the flywheel. Presumably the flywheel will have similar surface damage too. What I don't quite get is how the flange face is so damaged and yet the 'debris' from the hole deformation is still standing proud of the surface. Almost as if the surface damage was there prior to the hole deformation. A few comments from Vyv Cox would be informative here I would think...!
Anyway its all a bit academic now as europe172 has rebuilt and run the engine for several hours and thereby, I would suggest, taken ownership of the baby as his! Yer a braver man then me Gungadin!
 
ean_p said:
Anyway its all a bit academic now as europe172 has rebuilt and run the engine for several hours and thereby, I would suggest, taken ownership of the baby as his! Yer a braver man then me Gungadin!
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I think a few of us on this forum have the same engine from the same source so our interest is rather more than academic!
 
bedouin said:
I think a few of us on this forum have the same engine from the same source so our interest is rather more than academic!
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Rechecked the torque this morning, no bolt movement, painted marks on the bolts as witness marks.
The alternator belt seems to be wearing, as the alternator took the full weight of flywheel perhaps it has bent the alternator shaft ?
 
ean_p said:
If I didn't know better I would be tempted to think that the surface damage to the crank flange face was caused by rotary friction as if the flywheel had been rotating against it and the two surfaces had 'picked up' due to friction / heat. There is a degree of damage on the spigot circumference too which also looks like it was caused by rotation of the flywheel. Presumably the flywheel will have similar surface damage too. What I don't quite get is how the flange face is so damaged and yet the 'debris' from the hole deformation is still standing proud of the surface. Almost as if the surface damage was there prior to the hole deformation. A few comments from Vyv Cox would be informative here I would think...!
Anyway its all a bit academic now as europe172 has rebuilt and run the engine for several hours and thereby, I would suggest, taken ownership of the baby as his! Yer a braver man then me Gungadin!
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It was a difficult decision, I could have returned the engine for repair free of charge.
But the boat would be out of the water for an unknown period
 
europe172 said:
It was a difficult decision, I could have returned the engine for repair free of charge.
But the boat would be out of the water for an unknown period
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I hope it is OK for you but I would not have countenanced using that crank or the flywheel.

I have a horrible feeling that the surface damage was there when the engine was built, well before the flywheel fell off. What was the mating face on the flywheel like?
 
europe172 said:
It was a difficult decision, I could have returned the engine for repair free of charge.
But the boat would be out of the water for an unknown period
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Yes I can appreciate you having been placed into the dilemma and one not of your making. Best wishes but keep an eye on it all!
 
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