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Old 23-09-2009, 06:16   #1
TOM
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Stuffing Box Always Hot

We are running in our new 4JH4-TE Yanmar 75hp. 24 hours running time so far .As Yanmar specifies we are running the engine in the high rpm range mostly 2800rpm .3000rpm for 10 minutes every half hour and wot {3200 rpm}for 4 mins every 30 minutes.

Problem is our stuffing box gets very hot .So i loosened it off a few turns so that iam getting a steadey stream of water and it is still getting hot.I recently replaced the flax and always make sure it has plenty of grease .

Could this be a product of running in the motor at very high rpm or have i got a more sinister problem ? I dont want to score the shaft but dont kow what else to do .has anyone had any exsperience with this .
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Old 23-09-2009, 07:09   #2
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I can think of 4 possibillities. Incorrect size of packing, too much packing, incorrect motor allignment, motormount not adjusted correctly.
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Old 23-09-2009, 07:18   #3
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just wondering how close your transmission is to the stuffing box. the shaft gets hot near the engine also. i would use the GFO packing.
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Old 23-09-2009, 07:20   #4
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Well i put the exact same packing and quantity in as i took out. I run a v drive so shaft position has not changed .Only thing i changed was my gearbox ratio 2.03 to 1.60
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Old 23-09-2009, 07:36   #5
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If you changed ratio, that would imply that you changed the V-drive? could this have possibly caused a mis-alignment?That would seem the most likely cause of the heating.
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Old 23-09-2009, 07:42   #6
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I dont know much about ratios, but isn't the shaft turning faster now at a given rpm than it was before? Or is it the other way around? Could this be a factor? I think Steve is probably correct as the v drive was removed and maybe not reinstalled correctly.
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Old 23-09-2009, 07:57   #7
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Very good question Steve C .I kept the same vdrive all i did was switch the gears around changing it from a 4:3 reduction to a 3:4 step up .I know this sounds complecated but the reason i did so was to avoid having to run a 22 inch prop .With the 1.60 reduction i can run a 16/10 prop.

Re shaft allingment i have no vibration and although shaft is runing very fast it appears to run sweet
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Old 23-09-2009, 23:04   #8
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If your shaft is turning faster then you have more friction.

You may need to inject water into the stern tube to cool it or go with a Tides tyoe shaft seal.
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Old 24-09-2009, 16:42   #9
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How hot?

There are varying grades of hot:-
1) Faint sense of warmth when cover is lifted.
2) Hand feels warmth when gently placed on top.
3) Part is very warm but hand can be left on top.
4) To warm to leave hand on top.
5) Too hot to place hand on.
6) Too hot to touch.
7) Smell of overheated material.
8) Smell of burning material.
9) Some smoke noticed.
10) Lots of smoke.
11) Sparks or flames.

Could you give us a sense of exactly how hot it is getting?

Have you tried (with the engine off) holding your hand over varying places and parts round the stuffing box to get a sense of how hot they are?

Since the problem has only occurred since the new engine was installed possible causes that come to mind are:-
1) Slight misalignment of propeller shaft.
2) Slight misalignment of shaft from V-drive
3) Propeller shaft has moved during engine installation and an existing groove/ridge is now being pushed against the stuffing box housing. If this is the case the V-drive may be just a little warmer.

Don't forget you have close to doubled (maybe trebled or more given the condition of the Leyland) your power so any fault that would not have been noticed with the old engine is now very visible.

If the drive train can be realigned so the propeller shaft is moved slightly aft (0.5mm could do the trick!) it may help if the problem is the propeller shaft rubbing against the stuffing box.

There is a significant risk in continuing with a "hot" stuffing box, but immediate repairs are likely to be very expensive.

Bet the boat goes great with all that power.
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Old 24-09-2009, 17:14   #10
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why the miniprop?
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Old 29-09-2009, 02:39   #11
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Quote:
Originally Posted by Boracay View Post
There are varying grades of hot:-
Quote:
Originally Posted by Boracay View Post
1) Faint sense of warmth when cover is lifted.
2) Hand feels warmth when gently placed on top.
3) Part is very warm but hand can be left on top.
4) To warm to leave hand on top.
5) Too hot to place hand on.
6) Too hot to touch.
7) Smell of overheated material.
8) Smell of burning material.
9) Some smoke noticed.
10) Lots of smoke.
11) Sparks or flames.

Could you give us a sense of exactly how hot it is getting?

Have you tried (with the engine off) holding your hand over varying places and parts round the stuffing box to get a sense of how hot they are?

Since the problem has only occurred since the new engine was installed possible causes that come to mind are:-
1) Slight misalignment of propeller shaft.
2) Slight misalignment of shaft from V-drive
3) Propeller shaft has moved during engine installation and an existing groove/ridge is now being pushed against the stuffing box housing. If this is the case the V-drive may be just a little warmer.

Don't forget you have close to doubled (maybe trebled or more given the condition of the Leyland) your power so any fault that would not have been noticed with the old engine is now very visible.

If the drive train can be realigned so the propeller shaft is moved slightly aft (0.5mm could do the trick!) it may help if the problem is the propeller shaft rubbing against the stuffing box.

There is a significant risk in continuing with a "hot" stuffing box, but immediate repairs are likely to be very expensive.

Bet the boat goes great with all that power.


I would say no 4 .There is no smell of burning flax i have had that happen before on another boat and it took a week to get rid of the smell! .I rang the mechanic who installed the motor to ask his opinion ,he was surprised and is certain the shaft is aligned correctly as during sea trials everything seemed fine no vibration or anything to indicate misalignement {silly me i should have checked the s/box}

He sugested I tighten the s/box up as much as posssible to squeeeze the flax and then let it off, this should eliminate any problem with the flax been put in incorrectly .Sounds abit far fetched to me but i will give it a go before i start looking at shaft alingent.

Hope your refit is going as planned.Everytime i get the urge to one day build a boat i have a look at your blog ,see how much work is involved and I'm cured!! for a while anyway.
The new motor is great Yanmar appear to make a very good product .All I have to do is sort out this s/box problem and well be right.
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Old 01-10-2009, 17:32   #12
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You mentioned new flax, and lots of grease. Did you possibly put some type of grease in there, that is clogging up the flax and not allowing it to cool the shaft?

I would have liked to use Gore stuff, but it wasn't available locally when I needed it, so I used traditional flax. No added grease though.
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Old 01-10-2009, 18:15   #13
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Too hot?

Too hot to keep a hand on definitely sounds too hot to be comfortable with.

Through fortuitous circumstance my stuffing box barely drips and runs cold. I'm not going to stuff round with it...

You're not wrong about how long it all takes. Just complying with standards (the Admiral's) seems to take forever.
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Old 01-10-2009, 18:55   #14
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The rule of thumb in my training has been to tighten the packing just enough to allow an occasional drop. New packing may take a little while to break in but not too long or it'll start to wear a grove in the shaft. #4 on Boracay's list seems about right but that may depend on the type of hull you have.

A finkeel design will have a deep/open shaftlog with lots of water in it. Whereas, a fullkeel will have fairly closed shaftlog with very little water transfer. But I would say if it doesn't get any hotter then #4 after running for an hour I wouldn't worry too much.

If your running a stream of water out and it's still hot, you may not have the flax in properly. The split line on each ring should be 90 to 180 off from each other. Have you considered Teflon packing????

Here's a couple articles that might help. Servicing Your Stuffing Box by Don Casey
Shaft and Stuffing Box - resources for cruising sailors


Here's a typical full keel or rudder type stuffing box. BTW- The first and last packing should be square to the shaft, not tapered like in the picture. It's proven to cause misalignment of the follower.

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Old 02-10-2009, 15:14   #15
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FWIW - invest in an IR laser thermometer - they're as cheap as $US30 or even less. I've verified that my stuffing box, after running for hours, is a cool 89.8F when the water temp is about 68F. And virtually no drips, even without Teflon or Goretex packing...
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