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Michael Grew
Dec 5, 2009 - 12:04PM
Engine noise
My engine which is a 52 hp inboard Perkins diesel has recently started to make a strange grinding noise at low revs whenever the forward or reverse gear is selected. As soon as the revs are increased above idle speed the sound dies away.Can anyone suggest what this could be? I suspect (but hope it isn't)a bearing in the gear box
SeaDog Name (if owner or crew) Seascape
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Graham
Dec 5, 2009 - 12:19PM
Re: Engine noise
Hi,
If your engine is an 'original' it is probably either a Perkins 4107 or 4108, usually rated at 37Hp in the SeaDog as the max rpm is usually limited to less than 3000 by the propeller size. Other users of this engine run them at up to 3,800 rpm hence the higher BHP quoted sometimes.
Assuming the 4107/08 then you probably have one of the Borg Warner VelvetDrive gearboxes. These are wonderful bits of kit and rarely give problems (when we changed our engine for a Betamarine we retained the original gearbox).
The sound you are describing sounds like a known problem relating to the thrust plate, from memory the noise is not a major issue but when the gearbox can next be accessed then there is an improved non-perkins part that should be fitted.
Eric Richardson has all the details and I am sure he will respond to your inquiry shortly.
regards
Graham
SeaDog Name (if owner or crew) Dougal
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E Richardson
Dec 6, 2009 - 9:32AM
Re: Engine noise
Hi Michael
Sounds ominous, It may be the drive plate as Graham says, but thats usually more of a rattle than a grinding sound. Lets work with the grinding sound!
Remove the fan belt and try it for a brief spell (No more than a couple of minutes as the cooling water is not circulating) If the noise has gone then it's either the water pump or alternator.
Next change the gearbox oil fill it with ATF fluid, it could be water in the oil which would cause a drop in clutch pressure and lubricity causing the plates to grind when engaging. Put the oil removed in to a container to see if water is present.
The Borg Warner Velvet Drive Gearbox is very forgiving.
They are the first moves to make, Engine horse power depends on the calibration of the fuel injection pump. For the Seadog it should be set to 3,000 rpm which equates to 36hp. The higher settings are for motor vehicles or cruisers with higher speeds. The Prop on a Seadog should limit the engine to something just below 3,000 rpm if it is correctly sized.
Please give me a ring if you wish.
Eric Richardson
SeaDog Name (if owner or crew) Ex Taliesin
Michael Grew
Dec 6, 2009 - 3:39PM
Re: Engine noise
Thank you both for your very prompt and informative replies. I will do as you have suggested and let you know how I get on.
Regards
Michael
SeaDog Name (if owner or crew) Seascape
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Graham
Dec 6, 2009 - 3:44PM
Re: Engine noise
Hi Eric,
Would I be right in saying that if the noise only happens when forward or reverse gear is engaged then it is more likely to be related to the transmission?
regards
Graham
SeaDog Name (if owner or crew) Dougal
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E Richardson
Dec 6, 2009 - 3:49PM
Re: Engine noise
Hi Graham
Yes you are correct. That rules out the need to do the fan belt test.
Eric
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