Packing Box Maintenance

There are several different types of packing boxes, including the dripless because they are lubricated by water from the cooling system. Most other boxes are very similar. They form a sleeve or a chamber around the shaft that contain, as we call “packing”.  Which water can’t flow through when it’s compressed; however, the packing allows the shaft to spin.  The packing is compressed around the shaft by tightening the packing nut to the point at which it drips only occasionally and remains barely warm when in progress. This is the importance to checking the packing box whenever taking the boat out.  Because when the packing is gone or disappears, allowing more than 12 drips per minute to penetrate the bilge while in progress, or allowing any water at all to enter when standing still, then you need to follow the next step.  Try tightening the packing nut and it should solve the problem, but if it does not reduce the flow, then it causes the packing box to become more than warm to the touch. And that means it’s time to renew the packing. 

How to Renew Packing Box:

1.  First have to back off the locking nut. Water will flow into the boat when the packing nut is loosened, so be prepared or do this job when the boat is hauled. Position yourself so you can reach the packing box with two wrenches.  Crescent slip-joint pliers with jaws to fit will be nice to have too. (Sometimes you may have to resort to a hammer and punch.)  Each wrench handles should be moved toward each other to loosen, away from one another to be tightened. When the lock nut is loose, remove the packing nut.

2.  Get rid of the old packing material with a pick of some kind. The best picks look like a corkscrew and have a flexible shaft, but you can make your own pick.  Packing boxes have the packing inside the hollow core of the threaded sleeve. But be careful, sometimes you will find it in the packing nut instead of the sleeve. It doesn’t matter what kind, just make sure you take out all the old packing. Also make sure that there is no sand or grit left behind because that could score the shaft.

3. Cut pieces of packing material to the proper length to go around the shaft in a full circle. Typically, you can determine this length by using a fabric tape measure or a string.  Be sure not to wrap the packing material too tight around the shaft because your rings won’t seal.

4.  Wrap the rings of packing material around the shaft between the sleeve and the nut. The points at which they come together should be staggered, with layers.  The three layers should be at four, eight and twelve o’clock, and with four layers at three, six, nine and twelve o’clock. Now push the packing nut over the rings so they enter the nut.  The packing material must then be pressed into the nut tightly with a small screwdriver. (Screwdriver blade needs to be blunted so it will not dig into the packing)

5. When the packing is tightly seated, tighten the packing nut and then loosen it to see if the packing still looks consistent. Tighten it again with a wrench, but don’t apply too much pressure. Run the boat in gear and monitor the drip. Now tighten the nut until the drip decreases to fewer than 10 a minute. The following day, run the boat again and check the drip.  If it’s in the three to six range, tighten the lock nut hard against the packing nut, using the wrenches as described in step 1.

Don’t forget that you need to check the warmth of the packing box whenever you take your boat out. Also you need to check the “packing” and make sure that it’s still there and has not dissolved.

Good luck!!!

This picture shows the shaft, packing box, packing nut, the homemade pick and the packing.

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