Knocking Noise Diagnosis

MarieK

Member
Joined
3 Mar 2009
Messages
393
Location
Northern Ireland
Hi

Twin shaft mobo, KAD300 with hs63 gear I have a distinct knocking/tapping noise coming from gearbox area whenever I engage forward gear. It is not a consistent noise and it disappears immediately if I lift revs above idle. It is not present when engine is in neutral or when going astern.

I am thinking perhaps shaft bearings are going/gone - would this type of noise be consistent with that?
 

bluerm166

Active member
Joined
29 Sep 2009
Messages
979
Check for loose greasing lines/cables rapping on the hull.Can produce a remarkably mechanical tapping noise .
 

Gsd

New member
Joined
2 Aug 2014
Messages
15
I had same problem with a shaft drive boat with kamd44
It turned out to be gear chatter I changed the couplings on the flywheel for r/d high defeletion couplings never had the problem again
 

Gsd

New member
Joined
2 Aug 2014
Messages
15
You can adjust the idle speed up a little
The edc will only let you go a little you will need to look in book to see how it's done
 

spannerman

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Joined
30 Nov 2002
Messages
3,118
Idle speed should be between 600-700rpm, to adjust turn key to 'S' position and release.
Hold down Neutral button while turning key to 'I' position ( ignition on).
Diagnose lamp lights up, release N button when Diagnose lamp goes out.
Both Neutral and diagnose lamps will now flash to confirm you can adjust idle speed.
( If both engines req adjusting repeat above procedure for other engine so both can be adjusted at the same time)
Start engine and adjust idle speed with lever to desired speed.
Confirm set speed by pressing Neutral button.
Finish adjustment by returning lever to neutral position.
Note this can only be done from main control panel and should be done with engine warm.
 

Jim@sea

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Joined
12 Feb 2010
Messages
4,205
Location
Glasson Dock
An old trick is to get a long screwdriver, place it on the gearbox/engine (or where you think the noise is coming from) and stick your ear on the other end, this helps to identify where the mechanical noise is coming from.
 

Montemar

Active member
Joined
17 Jan 2011
Messages
793
Location
Dorset
An old trick is to get a long screwdriver, place it on the gearbox/engine (or where you think the noise is coming from) and stick your ear on the other end, this helps to identify where the mechanical noise is coming from.

Put the handle end on your ear for best results
 

Firefly625

Well-known member
Joined
18 Mar 2009
Messages
6,381
Location
Home=Surrey / Boat=Hamble
sounds like drive plate chatter... pretty standard on those gearboxes I thought...?

if it stops when a few more rev's applied then I am pretty sure that is what it is, and nothing to worry about IMO..
 
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