Hurth Gearbox on a Yanmar

[jfkal]

I go a Yanmar 3HM30 with a Kanzaki Hurth Gearbox KM3-P. Sometimes when I go in forward I hear a droning/rumbling noise. Going out of gear and back in, all is fine. First I suspected my folding prop not unfolding all the way or the shaft anode may have slipped and grinding against the P-bracket. Went diving, cleaned and checked everything is fine.
Additionally when running at higher RPM for some time the normal engine sounds get overlayed by a similar but fainter grumbling which comes and goes.
I now suspect the clutch slipping accasionally. Anyone had a similar experience or idas what it could be and or how to test the clutch?

 

[haffiman37]

Probably not the clutchsystem.When they fail you will normally have what is called a 'delayed shift engagement': it takes some time for the clutces to engage or they only engage when you encrease the rpm. What you may have is a ratling from the clutch disk pack that is not in use, there are seperate disk packs for forward and revers. On the other hand it may be a vibration noise caused by frequency which is very hard to find. My sugestion will be if the clucth system engages normall -forget them. If it is a bearing problem it would be all over the rpm range. If problem is only at certain rpm's - stay awy from that rpm range.

 

[jfkal]

Thanks. The second problem starts appearing after a while. I.e I run at 2,500 rpm for about 10 mins and then ist starts, so it does not seem to be a harmonic problem. I will observe and see whether it gets worse.