Stuffing Box Get Hot!

[roniszoro]

I have just had my stuffing box hose replaced and the stuffing box repacked. The stuffing box drips at 30 drips per minute when motoring at low RPM and gets quite hot, 140*. I would expect it to drip quite a bit at first as the packing get seated but not to be hot. Incidentally, it does not drip when the shaft is not turning. What's up?

Thank you in advance for your thoughts.

 

[Justin_NSA]

Friction. I'm not familiar with stuffing boxes yet but my guess is it is too tight (?)

 

[Ralph Johnstone]

The stuffing box drips at 30 drips per minute when motoring at low RPM and gets quite hot, 140*.

Hi roniszoro,

This is certainly not meant as a criticism of your packing skills, but I've learned over the years that packing a gland is a real art in order for it to work properly. I pack mine carefully enough as to be able to run it bone dry. See a few posts down from today.

http://forums.sailboatowners.com/index.php?threads/wet-bilge.180746/

Check the type of packing packing you're using. A good soft basic packing is teflon impreganted flax.

Check the size of packing. You should only need to tighten the nut hand tight. If it's too small, you tighten the bejabbers out of it (with a wrench) until it contacts the shaft all around. By that time its hard and not conducive to good sealing.

Be careful not to cut the packing too long. Any overlap on the bevel and you've got a bulge. The bulge doesn't help the seal. Too short causes leaks through the gap.

 

[Alan Gomes]

Definitely refer to this previous thread: http://forums.sailboatowners.com/index.php?threads/dripless-shaft-packing.153899/
MaineSail's comments in Reply #20 are especially helpful (as always). But the entire thread is worth studying.

 

[roniszoro]

Hi Ralph:

No offense is taken as I paid someone else to do the job and the bill was an amount in the neighborhood of the national debt of Guatemala. The fellow seems happy to return to make necessary alterations, but I want to know what you all think tho alterations should be.

Regards,
Ron

 

[JohnVTX]

Too hot and way too many drips. Something is wrong with packing type or size.

 

[Ralph Johnstone]

but I want to know what you all think tho alterations should be.

A complete re-pack because it's overheating while excessively leaking.

 

[kito]

So it only drips when shaft is spinning. Does it start dripping 30 drops a minute from a cold start up or does it gradually drip more when it heats up? Did he notice any scoring on the shaft where the flax seal is? Sorry, I have more questions than answers. It just seems strange to have that much water flow and still get that hot. Did you notice any metal on metal noises coming from that area? It could be the wrong size flax and the shaft is rubbing on the stuffing nut. But then it would drip all the time.........

 

[Siamese]

That many drips and it's still hot. Yeah, that's weird.

Do you have any legitimate reason to think the guy that did it knows what he's doing?

 

[woodster]

read mainsails tutorial on packing a stuffing box and see if anything you read looks like what your mechanic did ....it's either in p base or musings with mainsail

 

[heritage]

Curious that you can count the drips while the shaft is turning. On my boat, any water coming from the gland is flung about the engine room. Maybe the water is coming from the stuffing box hose connection??

 

[woodster]

Curious that you can count the drips while the shaft is turning. On my boat, any water coming from the gland is flung about the engine room. Maybe the water is coming from the stuffing box hose connection??

good catch

 

[Alan Gomes]

That many drips and it's still hot. Yeah, that's weird.

Do you have any legitimate reason to think the guy that did it knows what he's doing?

It is weird that it drips but still runs hot. But have you (the OP) confirmed that the drips are coming out the front of the stuffing box (i.e., where the shaft exits the packing nut toward the transmission) or are the drips coming out of the back of the nut? If the former, it's hard to see why the nut would be so hot. As you look at the shaft where it exits the nut does it look moist?

Since the shaft runs at a downhill angle, drips from the front of the gland will run downhill on the underside of the box and then likely drop down at around the aft end of the box. But that's where they will also drop down if, for example, the nut isn't tightened properly. So I could imagine a situation in which too much or too tight of packing was jammed into the gland, which would make the shaft run hot on the front end but would leak water out the back end. If you are just focusing on the drips you might not have noticed their point of origin.

My suggestion is to repack it with the proper sized packing. The packing should be snug but not overly tight. If you have to hammer it in then it's much too tight. You should be able to press it in without a great deal of difficulty. But there should be some friction so it is not flopping around loosely, either. I wish I could quantify it, but I'd just say "snug, not tight," if that tells you anything.

If you use the dripless packing (recommended), then adjust it so it is "drip less" but not bone dry. A thin film of water (at least) is needed for lubrication Buck Algonquin, one of the major stuffing box manufacturers, specifically says that some moisture is needed regardless of the type of packing used, including dripless. An ideal adjustment would be no drips with the shaft not turning and a slight weeping of water (out the front of the gland) when rotating. This should be sufficient to cool it. Again, consult the thread for which I provided links earlier as it contains some good info. Also, MaineSail has a good tutorial on how to pack a stuffing box on his excellent Compass Marine site (http://www.pbase.com/mainecruising/stuffing_box)

 

[MitchM]

something's wrong. our flax packing is 10 years old. with the grease gland properly adjusted, we get a drip rate of several drips a minute with p shaft turning, and zero with engine off. your drip rate sounds excessive. it sounds as though there's a bad seal at the shaft end, possibly due to a bad overlap and/or improper beveling of the flax rings. this job should not require $$ similar to the national debt of guatemala. how many p- shaft packing glands did your mechanic actually repack before yours? Nigel Calder's 'boat owners mechanical and electrical manual' has an excellent chapter on redoing flax packing. It's my go to boat Bible, has never done me wrong, and has saved me a fortune in yard bills. strange how many 'mechanics' don't abide by its suggestions...