A close call.

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nicho

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We were supposed to be relocating to Chichester Marina today, but we are still firmly alongside at Swanwick. I thought I would run the engines yesterday (KAD 44's), and noticed that the port unit seemed to be vibrating, a bit like a misfire. Opening the engine hatch revealed a nasty "clanking" sound, and I saw that the bottom pulley (some kind of crankshaft vibration damper) was very loose, wobbling like crazy. It was causing a bad vibration. Immediately switched off, and called a Volvo engineer. It appears that the bottom pulley, all 10 kg of it, was about to fall off, having three of the retaining bolts sheared, and the other two loose. Had that come off at 3000 rpm, heavan knows what damage to the engine room, and the engineer reckoned he'd seen one blow a hole in the bottom of the boat!! Now that scared SWMBO to death - she hates being at sea already!
New bolts are on order, and those sheared flush will have to be drilled out. The engineer reckons they failed having been overtightened at some time - the s/board one will be checked too. Anyone come across this before? We hope to depart now on Wednesday, confidence a bit dented!
 
nicho said:
We were supposed to be relocating to Chichester Marina today, but we are still firmly alongside at Swanwick. I thought I would run the engines yesterday (KAD 44's), and noticed that the port unit seemed to be vibrating, a bit like a misfire. Opening the engine hatch revealed a nasty "clanking" sound, and I saw that the bottom pulley (some kind of crankshaft vibration damper) was very loose, wobbling like crazy. It was causing a bad vibration. Immediately switched off, and called a Volvo engineer. It appears that the bottom pulley, all 10 kg of it, was about to fall off, having three of the retaining bolts sheared, and the other two loose. Had that come off at 3000 rpm, heavan knows what damage to the engine room, and the engineer reckoned he'd seen one blow a hole in the bottom of the boat!! Now that scared SWMBO to death - she hates being at sea already!
New bolts are on order, and those sheared flush will have to be drilled out. The engineer reckons they failed having been overtightened at some time - the s/board one will be checked too. Anyone come across this before? We hope to depart now on Wednesday, confidence a bit dented!
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Yikes. Well done for spotting it.
It's hard to tell without seeing the exact application and design of te parts, but perhaps consider thethr they're more likely to have failed due to being not tightened enough than due to being over tightened. I'd be worried about your engineer under tighten the new ones. Volvo will specify a torque somewhere so work from that and don't let them engineer suck his teeth and tighten them a bit less. The science behind this is that bolts that are subject to cyclic loading suffer a lower stress cycle amplitude if you tighten them more, and it is the amplitude of the stress cycles that kills the bolt ( by fatigue) rather than the static load from tightening them in the first place
 
jfm said:
Yikes. Well done for spotting it.
It's hard to tell without seeing the exact application and design of te parts, but perhaps consider thethr they're more likely to have failed due to being not tightened enough than due to being over tightened. I'd be worried about your engineer under tighten the new ones. Volvo will specify a torque somewhere so work from that and don't let them engineer suck his teeth and tighten them a bit less. The science behind this is that bolts that are subject to cyclic loading suffer a lower stress cycle amplitude if you tighten them more, and it is the amplitude of the stress cycles that kills the bolt ( by fatigue) rather than the static load from tightening them in the first place
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Thanks JFM. The guy who owned the boat before us (Cranchi Endurance 39) was a self proclaimed marine engineer, but frankly seeing the state of the engines when we bought it, he was little more than a grease monkey. Luckily, Boats.co.uk were more than fair with their 3 month warranty, and paid to have everything fixed by our own first class Volvo engineer - it cost them a considrable sum. They even extended the warranty to 6 months.
It will be interesting to get his view over the tight or loose scenario - luckily, I am sensitive to "noises"����
 
nicho said:
Thanks JFM. The guy who owned the boat before us (Cranchi Endurance 39) was a self proclaimed marine engineer, but frankly seeing the state of the engines when we bought it, he was little more than a grease monkey. Luckily, Boats.co.uk were more than fair with their 3 month warranty, and paid to have everything fixed by our own first class Volvo engineer - it cost them a considrable sum. They even extended the warranty to 6 months.
It will be interesting to get his view over the tight or loose scenario - luckily, I am sensitive to "noises"����
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You couldn't ask for more.....great service.
 
petem said:
What needed fixing Mike?
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Major issues - one alternator u/s, one supercharger clutch replaced, one outdrive clutch replaced, prefilters bunged up having not been serviced for some time, all filters replaced, tappets way out, cockpit fridge replaced, fuel polished to clear diesel bug - all done under warranty. The boats in nice condition generally, but let down by a moron previous owner trying to maintain the engines himself. Our Volvo guy did a great job on the engines on behalf of Boats, but this thing came out of the blue. I guess it's not something you would normally check.
 
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I'd insist they change the polygon hub that the damper attaches to as it has the threads that matter, they will have to take it off to drill them out so it would be a lot easier to replace the hub and the damper.
 
nicho said:
Major issues - one alternator u/s, one supercharger clutch replaced, one outdrive clutch replaced, prefilters bunged up having not been serviced for some time, all filters replaced, tappets way out, cockpit fridge replaced, fuel polished to clear diesel bug - all done under warranty. The boats in nice condition generally, but let down by a moron previous owner trying to maintain the engines himself. Our Volvo guy did a great job on the engines on behalf of Boats, but this thing came out of the blue. I guess it's not something you would normally check.
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Makes sailing look cheap :)

atb with the season :encouragement:
 
Jobs a good 'un! Had Andy Parham over today. He stripped everything off, drilled the sheared bolts out, cleaned off everything, rebuilt with new bolts, new crankshaft oil seal, and some lovely green Volvo paint to finish off. The s/board engine pulley is fine, but he checked the bolts were torqued correctly. The engine's now as sweet as a nut, vibration (that has been there for some time, but which I assumed was normal) all gone, and good to go. Chi and new berth tomorrow (barring some other unforseen.......!!)
 
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