The old "Hot Box" thing again ... stuffing box that is!

[Dan-Q]

Can anyone tell me how water can crawl up to packing gland underneath a runabout mooving on top of a lake at 32 MPH???
My newly finished 1954 Hunter's Marine 18ft runabout w/283 CC engine is giving me heating problems at the stuffing box. I've replaced the flax twice, have little or no compression on the gland (waiting for the first drips to tighten) and still don't get enough cooling.
We have owned a few sail boats and never had this problem ... basically because they mooved at a snail's pace.
I'm considering installing a small piece of 3/8" copper tubing underneath the boat just by the shaft opening in the hull in a "U" shape so that at speed, water goes through the tube and sprays up at the packing. I will set the tube in epoxy.
Has anyone ever tried this??

Thanks for the replies
Dan-Q

[bugeye]

hi,
Sounds to me that you have an engine/shaft alignment problem. That is assuming that you haven't over tightened the stuffing box.

[Quk&DrtyPete]

I agree with Buckeye. After the boat has sat in the water for a time, assuming that you trailer it, disconnect the flange bolts that connect the transmission to the stuffing box and slide a feeler guage .003 or so around the flanges, hold them together with your fingers, the clearence between the two should be the same all the way around. If not adjust your engine mounts until the clearence is the same all the way around the flanges. That should do it.

[Dan-Q]

Thanks guys for the feedback.
If I did have a misalignement problem that would become vibration. At present time my alignement is quite fair as it was checked on my last outing.
My point is how can water come up the stuffing box and cool the packing like it's supposed to do when the boat is mooving forward at 30 knots?
The shaft comes off the transmission at a 14* angle, goes through a cigar shaped hole in the hull and to a strut and prop. If I were going backwards I would have no problem. I just wonder HOW the water could possibly work its way up there against the flow!!??

Regards

Dan-Q

[Dan-Q]

Thanks RKROUGH,

As I stated in my original post, I have no compression on the packing. So much so, the 2 nuts came off the gland from the engine buzz. On my first trial run I had 3 rings of flax in there moderatly compressed. I found out it was too tight real soon by the heating of the box. I backed off the nuts and got a very small drip ... not enough. So I pulled the shaft and box and replaced the old flax with 2 rings of new stuff. I put a little compression on the flax just to give it shape around the shaft, then backed off completely.
At slow speeds I get a drip but none at speed.
I'm no rocket engineer but I just can't make out how water can crawl up the inside of the stuffing box to the packing ... about 5 or 6 inches higher ... and cool the flax and gland while the boat is on plane.

I'm going to try my idea about a small (3/8") piece of copper tubing shooting water up the box and see what happens ... I'll let you know next week!!

Have a nice day :confused:

[On Vacation]

Many hig speed boats have a stuffing box with a cooling tube connected to the top with water taped off the side of the heat exchanger or in raw water cooled, the exhaust outlet.

One other thought, if you are using the teflon type packing, try to find the older style waxed cord and see if it runs cool. Also just check to make sure the size is correct. Many times a shaft will not vibrate at top end speed if it is misaligned. Did you upgrade the type stuffing box from the original one?

[ 08-20-2002, 07:56 AM: Message edited by: oyster ]

[GROOVY]

Dan, I understand what your saying, and untill now have not thought much about the packing on my just launched boat. But if everything else is aligned, square and there are no buggers on shaft or anything else to cause friction I wonder if leaving a gap at ends of first ring of packing would help?
How long do you run before it gets hot and how hot does the stuffing box get?

[Dan-Q]

Hey Oyster and Groovy,

Oyster, I am using the waxed packing ... flax. But I'm going to give the teflon a try. I beleive it has a higher heat endurance.
I beleive the stuffing box to be original. But I've seen other ones and they are not different to mine. I think its shape and angle to be up to today's standards ... afterall the boat is only a 1954 ... not all that old. But cooling from the inside could be another option. Thanks for the idea.

Groovy, you ask how long do I run ... well I can go all day at 10 MPH because I'm on the step but when I get on plane it heats up quite fast ... a couple of minutes.
Actually on my last run, the wax melted and dripped just below the gland. I've read that this is a normal reaction to a box that is overheating.
I do like your idea of the gap on the rings. I'm going to save that one. On this coming friday I will test my "underwater cooling tube" and see what that does. I don't want to try more than one thing at a time for then I won't know which is working.

Thanks guys, and I'll let you know what happens
Don't forget ... only popcicles are cool!!

[On Vacation]

Dan, if it happens in just a few minutes, I would have to look at the actual size of the packing being too large. It should not run hot at all. I will send you a shot of the cooling tube on our stuffing box. But if it never had one and this is the orignal one, then it should need one now. Just my thought. One more question, how long has it been since the boat has been run?

Also is the shaft new? Could it be that the shaft size is changed allowing it to run against the nut? Being in Canada, is the shaft size metric? On some oriental boats, we would run into this with attempting to fit American propellers on them.