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les1ey...
les1ey...

Posted: Sun Aug 21, 2011 7:43pm

Post Subject: Scuffing Noise maybe from PRM Gearbox with Trolling Valve

Hi My Dad has a 57' narrowboat with a 30 bph Beta Marine PropGen diesel engine and I think a PRM gearbox with trolling valve. I believe the engine is run at a constant 1500 rpm, (charging battery bank for a gas free boat). The boat is 10 years old but I would be very surprised if it had as much as 2000 engine hours, probably less. A few years ago a fairly loud mechanical scuffing sound started to happen, apparently randomly, usually after a few hours running. It does not seem to happen if they are not travelling. It usually goes away I think if they slow down a lot or stop for a while. They have had all the stern gear (though hull, thrust bearing etc) replaced, to no avail. I'm wondering if it's the gearbox though my Dad says he thinks the noise is from further back. There are 2 universal joints between the gearbox and the part it rotates - sorry not too clear on this - (so shouldn't be alignment problems). I am hoping someone can help because this is really getting him down and stopping him using the boat. He can't seem to get anyone willing to travel to Yorkshire to look at it. It would also help to know if it is likely to be serious or cause sudden loss of power - it is putting him off navigating any rivers. Many thanks Lesley

Tony-B...
Tony-B...

Posted: Sun Aug 21, 2011 9:25pm

Post Subject: Scuffing Noise maybe from PRM Gearbox with Trolling Valve

I can not be much help and suspect you need to involve Beta in this. I understand the Propgen is no longer produced. A Scuffing noise does not sound much like anything I would expect as long as nothing is fouling the propshaft. I assume the prop has been checked and is free of debris. It would be a good idea to change and retention the alternator drive belt(s). I also wonder if this is a manifestation of a singing prop. If it is simply ignore it or have the prop edges ground when next out for blacking. To be honest I would not expect a UJ or the associated thrust bearing to produce scuffing noises. I would expect whines or growls. Can you record the noise and email it to Tony@Tb_training.co.uk NEXT WEEKEND so I can listen to it. Time is important because I do not want to be on mobile BB when I get the file but I do not hold out much hope of identifying the problem. Lets hope our readers have heard something similar. Tony Brooks

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