Singing prop? Or something else?

[richardf]

I have a feeling it might be something to do with the alignment - the short piece of shaft between the stuffing box and the centraflex coupling is very greasy - I didn't notice this before and I'm wondering if it due to heat as it passes through the stuffing box - although it was easy enough to turn the prop via the weedhatch.

I have noted that the engine is fitted on tall hardwood risers (this engine sits a lot higher than the Kelvin), but there doesn't seem to be any shims fitted. This means that either the wood blocks were machined exactly as required, or (more likely), they were relying on the centraflex to take up any misalignment.

If this has was excessive, then I guess it may have knocked out the bearing in very short order - it certainly wasn't doing it for the first 15 hours or so of use.

[RLWP]

That piece of shaft is always greasy, I'd be very worried if it wasn't. Excess grease from the shaft squeezes out of the ends of the tube

 

Richard

[Ally]

I'm going to agree it doesn't sound like a singing prop, they usually sing around tickover, annoyingly! And I think you said your prop wasn't changed anyway? Am I correct assuming you have a long shaft to a mid engine?

[nicknorman]

It certainly would be a good idea to check the alignment before (when) re-installing any repaired bits. Not quite clear about your setup, but on ours the centaflex bolts onto the gearbox flange and, having undone the flange bolts it is very easy to check both the positional and the angular alignment. The former because there is a lip and cup on the flanges, so they only go together easily if the positional alignment is correct. The angular alignment can of course be checked by looking for fresh air somewhere around the two (touching) flange faces.

[bizzard]

The engines mounting feet should not bear directly onto the wooden bearers as they are liable to sink in and upset the alignment, but should be mounted on a pair of lengths of steel angle or at least large area metal plates which are mounted on top of the wooden bearers with the engines feet sitting on them to spread the weight. Shim between mounting feet and angle.

And as Richard keeps mentioning ''listening stick''.