New stuffing boxes overheat!!! - The Hull Truth

Nitecapt · 07-11-2007, 01:41 PM

I am writing this for a friend

I have a 28 Rampage which I have just installed new stuffing boxes on reconditioned shafts. The dealer that sold me the stuffing boxes also reconditioned the shafts. The shaft slid very nicely into the stuffing box, not so loose that the shaft would slide out if left alone but it went in easily enough. Splashed the boat and ran it and the stuffing boxes are overheating at low speed even with the packing nut all the way out and a very slow drip is coming ouyt of the stuffing box tube. Once the shaft heats the dripping stops. When it cools they will drip again. Is this just breaking in or is something wrong?

yottyboy · 07-11-2007, 01:53 PM

Rest assured that a slight drip from a stuffing box, spinning or not, is absolutely OK. It depends on the type of packing, in that traditional flax packing without teflon will drip the most folllowed by teflon impregnated flax followed by synthetic impregnated with teflon followed by Drip Free packing. You should expect that ther'll be a little moisture at all times. In fact, if it isn't dripping it could mean that the packing is too tight, which can lead to scoring and premature wear of the shafts and packing. The water acts as a coolant/lubricant. It sounds like it's OK from the description.

homewrecker · 07-11-2007, 03:11 PM

Did you check your alignment,they should never run hot,were the stuffing boxes complete new units? what size packing do you have?

Nitecapt · 07-11-2007, 03:25 PM

It's not the dripping we are worried about. We expect that. It's the fact that the heating occurs and that the dripping stops! We would be happy if the dripping continued. We're talking about no drip and heat up with the packing nut backed off completely.
The packing is Flax/Wax with no teflon.

SIM · 07-11-2007, 03:58 PM

Quote:

Nitecapt - 7/11/2007 1:25 PM It's not the dripping we are worried about. We expect that. It's the fact that the heating occurs and that the dripping stops! We would be happy if the dripping continued. We're talking about no drip and heat up with the packing nut backed off completely. The packing is Flax/Wax with no teflon.

I assume that it is heating up while underway. Many inboard boats do this and most owners have no idea it is going on since they do not go in there engine rooms and actually check it.

The reason it is heating up is from the raw water being drawn awya from our out of that area while at planning speeds. It is common and is an isssue with the design of the hull and the area where the shaft exits the boat.

What you can do............the best thing to do would have been to install dripless shaft seals that are water injected (PYI comes to mind) when you had the shafts out of the boat.

We have also...... when the thickness of the bronze shaft log permits is to drill and tap a small brassfitting into the shaft log and run a small ID hose from a raw water source on the engine to that fitting. Right aft of where the packing is. This will keep the area water lubed when the engine is running, which should cut down on the heat and the constant adjusting of the packing after running the boat.

Andy

tobnpr · 07-11-2007, 04:19 PM

What SIM said may be correct, but it's a model-specific problem. My Sea Ray has very deep prop pockets which cause exactly the problem he mentioned. However, Sea Ray was aware of this and installed a round ring or "collar" just abaft the stern tube on the shaft to force water back up and into the stuffing box when underway. Because the boat now has (water injected) dripless seals they're no longer necessary. I would contact Rampage (are they still in biz?) to see if they are aware of such a problem.

It also occured to me that the packing diameter may be too large and might be sealing tightly around the shaft even with no compression from the packing nut. I'd check to see that the proper diameter packing was used...

SIM · 07-11-2007, 06:00 PM

Tob,

Good point......I forgot about those. They can be added without removing the shaft since they are split rings held togetherby allen head bolts. The only problem we see with them is that they like to slip down the prop shaft away from where the shaft exits the hull on occasion.

Is that a 34 Sundancer or a 39 in your pic? If its a 34..........god help the guy that has to adjust those shaft packings or change a centerline bilge pump. [img]../images/emoticons/biggrin.gif[/img]The 39's are much easier. Those both are common boats in our neck of the woods.

Andy

sammi · 07-11-2007, 11:39 PM

If the packing nut is all the way off and you are only getting a drip I wonder if the packing was too small and you forced a piece between the shaft and tha shaft log. When you pull the nut off, water should enter the boat rather fast. Maybe even some fishing line wrapped up there.

sammi · 07-11-2007, 11:40 PM

delete

Shark1007 · 07-11-2007, 11:49 PM

How many pieces of packing? Did you rotate the gap on the pieces?

I've removed one piece of packing before to enable the nut to be run down a little and to allow the device to cool. If she's hot at low speed, you've got a problem, maybe you should try the goretex stuff.

thataway · 07-12-2007, 12:41 AM

I agree there should not be that much heat (no more than you are comfortable putting the back of your hand on)--why rebuilt stuffing boxes? I have owned 30 year old boats with the origional stuffing boxes...Makes me think that mis alignment was a problem in the past--damaging the shafts and causing stuffing box problems. First check shaft alignment. Then pull the stuffing. Be certain that the correct size stuffing is used. Use teflon packing, with the teflon grease. If the engine is aligned, the stuffing box properly packed, there should be no overheating or excessive leaking. If the box is still heating, certainly drill and trap, with a small water flow to keep the shaft well lubricated.

Nitecapt · 07-20-2007, 11:04 AM

I think we have an answer. It appears that the stuffing boxes, which were NEW were actually too tight and need to be milled to allow more tolerance around the shaft. The dealer did not check the stuffing boxes and relied on themanufacturers specs. After we sopoke with him he checked soem on the shelf and found considerable variation in diameter. Add to this that normally 1.25" shafts are allowed to run a wee bit larger and we have a problem. Wish the dealer had checked the stuffing box inside diameters to match with the shafts instread of trusting in someone else's work.

I'll keep you [posted.