Prop Shaft Getting Hot near stuffing box ?

[Jobs a good un]

Hi All

Noticed my prop shaft is getting hot for about 12 inches between the engine and stuffing box ,its getting hot the stuffing box side .
Anyone know what causes this , is it normal ?

Regards
Mark

 

[Tranona]

Likely to be the packing is done up too tight and not allowing water through to cool it. Could also be over zealous pumping in of grease resulting in the tube being blocked and not allowing water in - or a combination of the two.

 

[Refueler]

Likely to be the packing is done up too tight and not allowing water through to cool it. Could also be over zealous pumping in of grease resulting in the tube being blocked and not allowing water in - or a combination of the two.

Which I was going to type as well ... but judging by posts in other threads ... I would have been accused of not understanding the stuffing box type :

1. Water is not to cool - its to lubricate
2. Grease is to seal and reduce water flow

But I totally agree ... if the packing is pressed too tight - it basically 'strangles' the shaft .. it can even over time create a groove.

If overtightened but not too far - it can be simply slack back packing gland nut .. run shaft to loosen packing - water will start to pass through ..... keep it going for a bit. Then bit by bit re-tighten till water flow is down to a steady drip every 10 - 20 seconds. Pump in a bit of grease ... watch drips .... With shaft stationary - you should be able to stop water drips with the grease, once motoring again - water drips should restart after a short run ...

If seriously overtightened - you can try above - but it may be such that removing the layers of packing is only way to loosen up again. Re-packing and then carry out the above till drip every 10 - 20 secs while running ... grease injection to stop drips at stationary.

Just a comment ... I repacked my seal over 15yrs ago .... never had reason to open up and repack. After each shaft run at end of day - I give 2 turns on my greaser to avoid bilge water. My shaft runs cool ...

 

[Boater Sam]

Be sure that the shaft alignment is correct and that the engine mountings have not sagged.

 

[Yara]

Those darn engine mountings. How are you supposed to know if the glue has failed and they are only resting on by weight? Remove them? I don't have a hardness tester, but even if I did, what Shore A number should it be?
Of course, the mounting bolts are impossible to get at on my boat. Ah, for the S&S Yankee 30 I nearly bought, with centre mounted engine, and complete easy access to the engine and the whole drive train all the way to the prop tube....

 

[Plum]

Just a comment ... I repacked my seal over 15yrs ago .... never had reason to open up and repack. After each shaft run at end of day - I give 2 turns on my greaser to avoid bilge water. My shaft runs cool ...

ditto !

www.solocoastalsailing.co.uk

 

[Refueler]

Those darn engine mountings. How are you supposed to know if the glue has failed and they are only resting on by weight? Remove them? I don't have a hardness tester, but even if I did, what Shore A number should it be?
Of course, the mounting bolts are impossible to get at on my boat. Ah, for the S&S Yankee 30 I nearly bought, with centre mounted engine, and complete easy access to the engine and the whole drive train all the way to the prop tube....

I despair of some boat builders .... my SR25 ... the engine bearers were solid hardwood and the engine bolts inserted from underneath. Engine must have been bolted to beams BEFORE beams placed into boat. When my engine mounts failed and we wanted to lift it out to replace ... it was impossible as only a few cms clearance under bolt heads to bilge. Engine was too tall to lift of before hitting bridgedeck.
We had to cut away cabin furniture, cut away the mounts and then get engine out still with mounts bolted up.
It was decided to refit using angle iron 'beams' - that way bolts were accessible ... could be drawn easily etc.

It proved its worth some years later when the engine seized and we had to change it ... unbolt, lift - slide out (the furniture when cut previously had been 'keyed' so went back together nicely and with hidden screws) ... replacement engine slid in .. bolted up ... furniture back ... job done.

 

[RogerJolly]

After a thrash I'd sometimes notice a sort of tarry smell, similar to what I've smelled near the vents on a big ferry.

Used to wonder if it's the grease in the stuffing box getting toasted. Didn't seem to be any ill-effects.

Got one of those Volvo rubber jobs now on new boat.