Overheating stuffing box

[skipmac]

Overhauled the stuffing box (along with just about everything else on the boat) which of course included new packing. Based on recommendations and reviews (including an endorsement from MaineSail) I went with the Gore GFO packing.

Shaft 1 1/2", space between the shaft and ID of the packing nut 1/4" by measurement. Also all the info I find on the internet specifies 1/4" packing so I bought 1/4" packing.

Diagonal cut 3 rings, loaded into the packing nut, loose hand tightened. When I launched the boat I verified I was getting a few drips/minute at the dock. Cranked the engine and in gear started about a drip every 5-10 seconds.

First time I ran the engine I didn't check the temp on the shaft, ran the engine about 45 minutes first run, about double that the second run. Checked and still had drips before the second run but when I checked the temp it was too hot to hold my hand on it.

Next day I pulled out one of the three rings of packing. Left the nut loose enough to get a slow trickle and ran it again. At idle in reverse (still at the mooring) withing 10 minutes the nuts showed 147 F. Also the slow stream had slowed to an occasional drop without any change in the nut adjustment.

Next test is to pull the two remaining rings for inspection (quickly before the boat sinks) and if they look ok, put them back loosely and try again.

BUT, any other ideas or suggestions? How come running so hot?

I read a comment from another member on another thread (that I can't currently find) that he had the same problem, put in a smaller size packing and problem solved. I may try this but all information indicates 1/4" is the right size.

[model 10]

I don't think you could get the wrong size in there unless you installed some sort of metric thing. But an american 3/16" nut is not going to let you fit a 1/4" packing which leaves 7/32" packing material, never seen that.

[skipmac]

3/16" and 1/4" is all I can find as well.

I'm thinking about trying 3/16" packing if I can't come up with a better idea. I think a little pressure on the nut would expand the 3/16" packing to fill the gap but won't know unless I give it a go.

The packing is pretty flexible and I could probably stuff over sized in the nut without too much effort but the 1/4" fit easily. No forcing, no wigging or jiggling to get the nut over it.

[model 10]

Is this a hose mounted stuffing or did you need to glass in something?

[skipmac]

Originally Posted by Guy

Is this a hose mounted stuffing or did you need to glass in something?

Boat has a fiberglass shaft log built in to the bilge with 6 ply hose clamped to the shaft log and the stuffing box.

[Lepke]

Sometimes the shaft log can get air and block any cooling water until you reverse strongly. My old style boxes have some of the exhaust water plumbed to them. Older boxes often have a zerk fitting on the box when sealing bigger shafts so you can grease them.
When I change packing, I put water proof grease on the shaft or rope seal where it will rub, for the break in period. Works on engines with rope style rear main seals, too.

[skipmac]

Originally Posted by Lepke

Sometimes the shaft log can get air and block any cooling water until you reverse strongly. My old style boxes have some of the exhaust water plumbed to them. Older boxes often have a zerk fitting on the box when sealing bigger shafts so you can grease them.
When I change packing, I put water proof grease on the shaft or rope seal where it will rub, for the break in period. Works on engines with rope style rear main seals, too.

Plenty of water coming through so can't be an air lock.

The Gore GTO packing is graphite impregnated so has built in lube.

[boatbod]

Are you certain there isn't another ring of old packing material jammed down in the base of the gland?

[skipmac]

Originally Posted by boatbod

Are you certain there isn't another ring of old packing material jammed down in the base of the gland?

Oh yes. Very sure. Just finished an overhaul which included pulling the prop shaft, new cutlass bearing, new hose on the shaft log and of course strip down, clean, lube and repack the stuffing box.

[Squanderbucks]

I think the normal operating temp of a stuffing box needs to be determined by consensus. I'm not sure that 147F overheating. Does it make any noise such as a whine or hum?

When I replaced my fiberglass tubes and installed new Buck Algonquin 1-1/2inch stuffing boxes (they use 1/4" packing - three pieces) I did all the work except pacing them. Standard (probably cheap) flax with PTFE was used. I could never get them to drip right amount. Either too little or too much. When packing nut was tightened to stop the flood the they ran hot over (180 degrees) and emitted a terrible whine. I had to make adjustments after every few hours of running. A real pain on a two week trip to the Bahamas.

When I returned fromthe trip I removed the packings and replaced them myself with Ultra-X all synthetic packing. No more excessive dripping and they ran 50 hours before needing any adjustment. Now just occasionally. I have not put the temp gun on them but suspect that they run warm but not hot. The material conducts heat so it is supposed to carry heat away from the shaft through the bronze gland and nut to help cooling. Next time I go out and do a run at full cruise I'll make a temp reading with a heat gun just for fun. However, I'm in the middle of spraying some new Awlgrip on the back deck to cover some blemishes and waiting for the rain to let up here in South Florida. All primed and ready to shoot the top color and then non-skid. Maybe a week or two before I go out and can get back here. Otherwise maybe someone else can tell you what their traditional packing runs at as far as drips and temperature.

[model 10]

It is supposed to get hot enough to melt the wax in old style flax seals. That's around 147 deg.

[boatbod]

You are supposed to be able to hold your hand on the bronze. If it is to hot to touch it is too hot for the packing. Approx 125F is a good number.

[skipmac]

Originally Posted by boatbod

You are supposed to be able to hold your hand on the bronze. If it is to hot to touch it is too hot for the packing. Approx 125F is a good number.

Not too hot to hold your hand on it is my understanding and 147 F is definitely too hot to hold

[artisanmach]

is the shaft properly aligned? it maybe rubbing on gland...

[Celestialsailor]

Skip...I went through that whole mess when I launched with the new Teflon packing. I couldn't.t put my hand on the bronze. After realigning, it didn't seem much better. After a few hundred miles, it was cooler. I'm going back in the water in a few months and may change back to the flax style. My worry was shaft friction damage.