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-   -   Drive train noise, stuffing box leak, etc (https://www.moyermarineforum.com/forums/showthread.php?t=10944)

LordGothington 11-28-2018 05:49 PM

Drive train noise, stuffing box leak, etc
 
Ahoy!

When motoring, I feel that the noise coming from the propeller area is a bit excessive -- sounds like I am on a B-52 bomber. But this boat is new to me, so I don't know what 'normal' sounds like.

Recently I have been doing a lot more motoring (650+ miles, and 600+ more to go). I have had to tighten the stuff box several times -- and it seems to be needing attention more frequently. I am on a Tartan 27 Yawl.

Additionally, I noticed that when in gear at idle speed I can see a noticeable wobble of the stuffing box.

I have no real idea if the noise and vibration are normal or not as I have only be on one other similar boat and it had a 3-blade prop.

Right now the boat is in the water -- I am at a facility that can haul it out if/when needed.

Since it is in the water it seems like a good place to start is to check the alignment. On this boat, the engine is a hard mount -- there is no rubber or other vibration reduction stuff. I found that all the mount bolts where a bit loose -- which is not a great sign.

The next step, I believe, is to loosen the 3 bolts that attach the shaft coupler to the transmission. I think I remove 2 and leave one loosely attached and use a feeler gauge to check the alignment.

If everything seems ok, then the next step would be to haul the boat out of the water.

Once the boat is out of the water I can try wiggling the prop around and see if there is too much slop in the cutlass bearing. Next I can remove the propeller and see if the wobble goes away. (Making sure to provide water for the cooling system) If the wobble goes away then the problem was probably an unbalanced propeller. If the wobble remains, it is more likely a bent shaft.

The next step is to remove the shaft (and order a new coupling -- perhaps the split one), and check if the shaft is straight.

So... I am currently stuck on the step where I loosen the 3 bolts holding the coupler to the transmission. With the boat in the water it is pretty hard to stop the shaft from rotating when I try to loosen the bolts. It is tempting to use a pipe wrench on the shaft -- but I've heard that is bad for the shaft. If I was certain to need a new shaft then it wouldn't matter, but I have not reached that point yet.

I've heard it said that an 18" pipe wrench can be used to grab onto the coupler -- but I would assume that would not be good for the coupler. I think in the situation I was reading about they were attempting to replace the coupler on the engine side and just needed to hold it still to remove the nut.

So far I have been soaking the bolts in penetrating oil. I am a bit fearful of using a torch to apply heat right underneath the gas tank. But I do have a small butane torch I could try.

If the boat was out of the water, I could use a 2x4 to stop the propeller from spinning.

So.. another option is to wait -- but I am not sure how bad of an idea that is. I am currently at Green Turtle Bay in Grand Rivers, KY. It's cold here and only getting colder. But I am headed to Mobile, AL where I was planning to have the boat hauled out. So I'd love to just wait until I get there.

But, I've read that the vibrations could cause damage to the transmission. Is 600 miles way too long to wait? Or not far enough to be a big difference.

In this boat there is very little propeller shaft sticking out and the only support is the stuffing box/cutlass bearing/etc that goes through the hull.

I have some other inconclusive data.

If I try to wiggle the shaft from inside the boat near the stuffing box, I can't really feel any play.

If I turn the propeller shaft by hand I am not able to see any wobble. I also tried putting a stick across the nut to amplify the movement and show it like an indicating needle across the hull. I still was not able to see any movement when turning the shaft by hand.

I do see the wobble in both forward and reverse.

I am sure that the tip of one of the blades is slightly bent -- not sure how much bend would be needed to cause issues. (I also don't know how it happened -- was like that when I bought it).

I have no idea when the stuff box was last repacked or when the cutlass bearing was last replaced. I know the engine was rebuilt a decade ago -- so perhaps then.

In summary:

1) can this wait another 600 miles

2) how can I get those bolts loose when I am in the water.

Thanks.

JOHN COOKSON 11-28-2018 08:10 PM

I don't know the answer to your question but I do have one of my own.
What is the dip rate out of the stuffing box when the engine is in gear?
If you get the packing to tight you can burn the shaft. Not good. Hope you haven't overtightened the stuffing.
IMO a bent prop would cause the the vibration. Any chance that there is something wrapped around the prop that is making the vibration worse?

TRUE GRIT

Edit: One time I had a racket that I was sure was related to the drive train. It turned out to be the alternator. I diagnosed it by removing the belt and starting the engine.

LordGothington 11-28-2018 08:22 PM

I have been pretty conservative when tightening.

I'll tighten it so that it only drips every minute or so when the shaft is not turning. Then motor for 10-12 hours and it will be dripping once a second when the shaft is not turning.

I am not sure how much is is dripping underway immediately after I tighten it -- because I am trying to dodge towboats and not run aground. Solo cruising on rivers makes it tough to spend a lot of time with my head in the engine compartment.

There is always a chance something is fowled on the prop -- but the noise has been there since I put it in the water. That said, I launched it in the Chicago river, so maybe it got immediately fowled.

I guess I should also add that I have been running down silty rivers like the Mississippi -- but none of the locals think the mud could be causing the stuffing to wear out faster.

Peter 11-28-2018 08:36 PM

Dear Lord,

I had some shaft wobble issues this spring after pulling the engine to replace the rear seal and thrust bearing. My repair was motivated by an oil leak but I decided to replace the thrust bearing while I was there and the subsequent reduction in noise was dramatic!!! It should not sound like a B-52.

The shaft should not wobble. This will put stress on the stuffing box and the thrust bearing.

How to loosen the nuts in the water - I had success using one of those rubber strapped oil filter wrenches around the coupling. However, my bolts had been removed very recently so maybe I had it easy.

You are on the right track re aligning. I read somewhere that one should try to get the height about right with the rear mounts and fine tune the alignment with the front mounts. This strategy worked for me.

Can it wait ? If it was my boat I would fix it. I think you risk further damage to the thrust bearing - perhaps catastrophic.

Peter

LordGothington 11-28-2018 09:04 PM

I'm looking at some pictures of adjustable rubber strap wrenches online and those looks very promising. I'll have to grab the courtesy car tomorrow and make a run to the hardware store.

My inclination is to not go anywhere until I have this issue resolved. I *think* I have made it far enough south that I will be able to get fuel and stuff even if I am delayed a bit longer. Though non-winterized pumpout stations are pretty rare these days. This place has a full service center and the pool and sauna are still open, the wifi is reliable, etc. So I'd rather be stuck here than some place where nobody can help me.

It's my understanding that the Atomic 4 uses SAE (imperial) wrenches, but it seems to me that the 14mm fits nuts a lot snugger than the 9/16. I'm tempted to pick up a longer 14mm wrench (for more leverage) unless there is some reason why using the 14mm would be more likely to strip the nut.

ndutton 11-29-2018 08:26 AM

Continued tightening of worn packing only serves to add drag to the shaft, does not manage drip for very long and at some point damages the shaft surface which will affect the replacement packing's ability to seal properly. You may even impart enough drag to stall the engine at low RPM. Since this boat is new to you it's doubtful you know the age of the current packing so based on your first post and the benefit of "making the boat yours" I suggest the time has come for replacement. You'll be amazed at how little pressure it takes for fresh packing to seal properly.

Al Schober 11-29-2018 09:51 AM

LG,
Backing off the coupling and checking the gap between the flanges will give you a good start. I recommend you put alignment marks on both flanges, then remove all the bolts. The shaft side of the coupling won't drop into the bilge as it has a pilot that fits into the engine side of the coupling.
Check the initial alignment - biggest gap & where? Then rotate the engine 180 degrees. Gap and location shouldn't change if the engine flange is running square. Do it again, but rotating the shaft and it's flange 180 degrees. Again, it shouldn't change if the shaft is straight and it's coupling is square.
If the propeller shaft isn't running true, doing an engine re-alignment is a waste of time and could actually make things worse!

LordGothington 11-29-2018 05:41 PM

Thanks to the rubber strap wrench and a lot of muscle, I finally got those bolts removed. But -- the two halves of the couple are still mated firm together. How do I create a small gap so I can check the alignment?

It is tempting to put the screws in almost all the way and put the engine in reverse so that the prop pulls the shaft back. Is that an awesome or a horrible idea?

Or maybe it mean I overtightened the stuffing box this time? I can still rotate it freely by hand, but I am more inclined to believe it is the coupler that is holding things together still...

ndutton 11-29-2018 06:11 PM

3 Attachment(s)
Here's the tool I made for this exact purpose and it works like a charm.

LordGothington 11-29-2018 07:45 PM

Quote:

Originally Posted by ndutton (Post 115190)
Here's the tool I made for this exact purpose and it works like a charm.

Nice. Are you concerned about that scratching up the faces? Or do you use it when you place to replace both halves anyway?

ndutton 11-29-2018 08:07 PM

No concern with a scratch on the face, we aren't building a watch here. Most folks are a lot more brutish (screwdrivers, hammers, etc.) than this.

It's available to you if you like, Priority Mail and you'll have it in two days.

LordGothington 11-29-2018 08:52 PM

If I don't get it apart soon, I'll take you up on that offer. My coupler looks like it shouldn't be that hard to get apart,

https://photos.app.goo.gl/daLrAM33DnKf86nw7

But looks can be deceiving I guess.

LordGothington 12-01-2018 03:49 PM

So, I managed to get the coupler separated by around 0.028" and use the feeler gauge to check the gap. It seem pretty even all around. I rotated the coupler and the flange around and the spacing did not seem to change.

But.. I never did fully disconnect the bolts so maybe my measurements are meaningless. I don't really understand what would hold the shaft in place if I did. On this boat there is a couple inches of shaft sticking out the back of the stern tube and a couple feet of unsupported shaft inside the boat.

I wasn't sure what else to do, so I put everything back together and took a video. The sound is annoying (and distorted)-- but it helps to be able to hear the engine speed.

https://youtu.be/dPEUImP0_4E

The wobble is most evident in the video at idle speed and seems to mostly go away at higher speeds -- though perhaps that is just because due to aliasing the vibration does not show up on camera. When I am on a longer passage instead of motoring around the harbor, I'll check what I can see with my eyes and feel with my hand.

Does the amount of wobble at low speeds seem concerning?

Also, I just tightened the stuffing box so that it does not leak when at rest. You can see if the video that it is quite wet around the shaft and sometimes flinging water around when the shaft is spinning. Should I tighten it even more? Perhaps I have never gotten it tight enough and that is why it seems to need so many adjustments?

The marina here is overwhelmed with work already and has no interest in this project, so I am going to continue to head south and try to gather additional data. I will also take another video, but at a higher framerate.

ndutton 12-01-2018 04:21 PM

Try running in gear with the shaft coupler unbolted and pulled clear of the engine. Compare the sound to determine if you have an engine/reversing gear noise or a driveline noise and get back to us.

You are absolutely correct that an alignment exercise will be meaningless with the coupler unbolted from the engine due to weight related shaft sag so don't waste your time trying it in the water. There is a way to do it accurately out of the water. It requires removing the stuffing box and its hose, shimming the shaft into the center of the shaft log with three wedges 120° apart and then aligning. With the boat out of the water check the bearing for wear. There is no point in aligning anything with a worn out bearing.

As for tightening the stuffing box further to control drip rate, please revisit my post #6 in this thread. At some point you'll damage the prop shaft. I cannot say you are at that point yet but based on the dialogue I have a sneaky feeling you might be.

Al Schober 12-01-2018 05:24 PM

LG,
Take out the 3 bolts. The shaft WILL NOT drop into the bilge - the shaft part of the coupling has a raised ring that fits into the engine part of the coupling. You'd have to move the shaft aft about 1/4" to disengage the spigot.
With the bolts out, you can rotate the two parts independently. If one has a problem, it will become apparent which one it is.

LordGothington 12-01-2018 08:45 PM

Quote:

Originally Posted by ndutton (Post 115211)
As for tightening the stuffing box further to control drip rate, please revisit my post #6 in this thread. At some point you'll damage the prop shaft. I cannot say you are at that point yet but based on the dialogue I have a sneaky feeling you might be.

Ok. I'll stay another day and repack the stuffing box. (Another first for me!) Pretty sure I can get the flax at the ship store here.

ndutton 12-01-2018 09:28 PM

Cool. Spend some time on the internet to read up on the process like three separate flax rings, joints 120° apart, different types of flax (I've been very pleased with the teflon impregnated flax).

Be sure to use the proper size too. I recommend removing one ring of the old flax and take it with you to buy the replacement. You can reattach the stuffing box with the remaining two rings to check the water inflow while you're away shopping. You'll ship water aboard during the process (a temporary wrap of tape really helps) but it's not much.

When reassembling the stuffing box, start out loose and slowly tighten to your preferred drip rate. No long sleeves when working around a turning shaft.

Marty Levenson 12-02-2018 01:39 PM

stuffing box
 
I'm always nervous working on the stuffing box in the water. It helps to be sure the bilge pump works and battery good. I also like to have silicone repair tape on hand to wrap it up if needed.

Marty (aka Nervous Nelly)

ndutton 12-02-2018 02:31 PM

Reading assignment including the link roadnsky provided:
http://www.moyermarineforum.com/foru...ad.php?p=69290

LordGothington 12-03-2018 05:44 PM

I repacked the stuffing box in the water. It's dripping multiple times a second at the moment because I read I am supposed to wait a while before tightening it down so that it can get water logged. I plan to motor around 4 hours tomorrow and then give it some adjustments.

As suspected, my shaft is scorched and scored. So, I'll have to replace that when I next haul it out of the water.

I'll just pretend that this problem already existed when I bought the boat -- which could be true. But there is a reason I bought a cheap (but quality) starter boat to make mistakes with. :)

Here is a photo of the old stuffing and the shaft. I can feel where the shaft is worn down in spots:

https://photos.app.goo.gl/SkTduWSA4wTCHduBA

What are the side effects of the shaft being warn down? How do I know when it has reached an unsafe amount of wear? I am hoping to do another 650NMi of motoring before my next haul out.

ndutton 12-03-2018 07:45 PM

You're probably correct that this has been going on for a long time but what you are seeing is the direct effect of continually tightening worn out flax attempting to manage drip. With fresh flax you'll be in better shape but do not expect to get an optimal adjustment against a scored shaft. It's gonna drip and if it doesn't you're likely too tight again. On the other hand, you risk nothing with this shaft, the damage has been done. Stuffing box temperature underway is a reliable method to monitor things. Consider 20°F above ambient water temp as the maximum allowable.

Administrator 12-04-2018 10:35 AM

Is there room for a PSS shaft seal?

Bill

romantic comedy 12-05-2018 05:41 PM

LG if you want to continue to be really cheap you might try replacing the packing hose instead of the shaft.

The packing hose is that special wire free, super thick hose that the stuffing box is attached to. The length is arbitrary and can be changed to move the stuffing contact surface to another point on the shaft.

The change can even be done with the boat in the water depending on the access and how confident you are.

JOHN COOKSON 12-05-2018 06:14 PM

Quote:

Originally Posted by romantic comedy (Post 115238)
LG if you want to continue to be really cheap(????) you might try replacing the packing hose instead of the shaft.
The packing hose is that special wire free, super thick hose that the stuffing box is attached to. The length is arbitrary and can be changed to move the stuffing contact surface to another point on the shaft.
The change can even be done with the boat in the water depending on the access and how confident you are.

I call a maneuver such as this practical not cheap.

TRUE GRIT

LordGothington 12-05-2018 07:28 PM

Quote:

Originally Posted by Administrator (Post 115227)
Is there room for a PSS shaft seal?

Bill

Probably. There is over a foot between the current stuffing box and the engine. And there are a couple inches of free space around it.


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