Stuffing box wobble

[Tinto]

Hi all
I recently gave a few turns to my stuffing box and have notice a wobble at it I hadn’t noticed before. It’s about 2mm maybe a bit more when at idle

more wobble at idle then when at 1000rpm
More wobble when in gear
Shaft turns freely by hand

any thoughts?

engine mounts were recently done my previous owner so I don’t think it’s them. Engine looks ok - no excessive movement

 

[V1701]

Bump...

Maybe time to repack it?

 

[alahol2]

If the engine is on flexible mounts and the stuffing box is on a flexible hose then a small amount of wobble is almost inevitable. I can't see it being a problem.

 

[Refueler]

Photo of the box showing its mount area as well ?

When you say shaft turns freely by hand .... you mean really easy ? No resistance at all ? Shaft should be turnable by hand - but slight resistance felt based on the packing ....

Some years ago ... I noted a slight wobble on my shaft ... it too was only mm's ... but I investigated ... finally had engineer take a look as I could not see why. Engine mounts appeared ok .. stuffing box etc. appeared OK .... but when engine run and shaft engaged .. there it was.
The 'culprit' was failed engine mount - just the one ... it looked fine but when he levered it ... the mount had failed inside leaving what looked fine on outside. It was enough to allow the engine to move such that shaft then 'wobbled'. The amount engine moved literally was hard to see ...

 

[vyv_cox]

Additional to Refueler's post, there is a condition known as 'soft foot' in which most of the engine weight is taken by three mounts, the other not being adjusted sufficiently. It is difficult to assess but careful use of a short spanner on the adjusting screw should help.

 

[scottie]

If the engine is on flexible mounts and the stuffing box is on a flexible hose then a small amount of wobble is almost inevitable. I can't see it being a problem.

Remember of the three items one must be solid (mounts gland coupling)

 

[alahol2]

Remember of the three items one must be solid (mounts gland coupling)

Maybe the OP can let us know.

 

[Tinto]

Thanks everyone for your suggestions. I will look into those and see what happens. Stuffing box re pack looks like a good idea, regardless.

 

[Tranona]

Maybe it is an optical illusion but it looks like the adjustment nuts are uneven so putting uneven pressure on the packing.

 

[Sandy]

Do you have a P bracket? If you do that might need checking. Says man who's P bracket is having serous GRP surgery at the moment then we move onto the stern tube.

 

[Tinto]

Maybe it is an optical illusion but it looks like the adjustment nuts are uneven so putting uneven pressure on the packing.

The gap between the two plates is continuous, so it is in alignment

 

[Refueler]

The gap between the two plates is continuous, so it is in alignment

The adjustment section - that 'compresses' the packing can actually be out of parallel quite a bit and not affect shaft as its a slack fit over shaft anyway - its job is to press on the packing - not to align the shaft.

BUT I agree that it should be evenly adjusted to be parallel to the fitting to avoid uneven packing pressure on shaft.

 

[Tinto]

Do you have a P bracket? If you do that might need checking. Says man who's P bracket is having serous GRP surgery at the moment then we move onto the stern tube.

I do yes. But it is solid. Cutlass bearing done last year

 

[Tinto]

So today I repacked the stuffing box and it is much improved, no more vibration