Cutlass bearing or something else?

[wpc691]

Wanted to take the Admiral out for an instructional cruise with the new AIS. Got 100 yds from the dock when we heard a loud squawking noise for a few seconds from the back of the boat. I first thought it was somebody putting down a lift - it sounded just like it. We went another 50 yds and heard it again. The Admiral took the helm and I jumped down in the engine room, heard the squawk again just as I lifted the hatch. Saw the shroud on the stuffing box on the port shaft pulsing up and down about 3/16” and the stuffing box leaking about 3 drops a second. Shut that engine down, and returned to the dock. Went back to the engine room, nothing seemed amiss except the stuffing box leaking a drop every 2 seconds. I backed the stuffing box off, then retightened (probably tighter than usual), slowing the leak to a drop a minute. Today, my diver went under the boat...I was thinking he might find a palm frond wrapped up in the shaft...but didn’t. Said the wheel, shaft and struts looked fine. Rotated both wheels, said the port was harder to turn than starboard...maybe that’s an over-tightened stuffing box. No runout that he could see in the shaft. I went down in the engine room while he rotated the shaft, and didn’t see or hear anything unusual. I tried to wiggle the shaft and couldn’t. I’ve read quite a few threads here about bad cutlass bearings, but I don’t recall any reports of loud howling noises or shaft wobble. It almost seems like that kind of motion in the shaft would have to come from the transmission end. The boat was running perfectly right up to the moment it started squawking - no noises, no vibration, although we were at idle, so maybe not surprising. Any thoughts? I’ll be back in the engine room tomorrow with a pry bar to see if I can get something to wiggle. Anything else I should look for or try? Should I just head for haulout before something really breaks?

 

[bayview]

Squealing fan belt?

 

[wpc691]

Squealing fan belt?

Don’t think so. The boat came with Carquest belts that really slipped. I switched to Cat cogged belts, and keep them snug. And there was no doubt the shaft was hopping up and down...not normal.

 

[DDW]

I had the forward cutlass bearing tighten up and nearly seize the shaft, but there was no vibration or shaft movement. And the prop could not be turned by hand. If the rubber in the cutlass has come unbonded, it could plausibly do what you describe under power, but still feel OK turning by hand.

 

[Larry M]

We had a cutlass bearing fail on another boat. The rubber separated from the bronze sleeve. At low rpms we had a high pitch noise. At highs rpms it was ok. From the water side you could see where the rubber had slipped back about 1/8 of an inch.

 

[Xsbank]

Disconnect the coupling and turn the shaft by hand. That may give you a better idea, then check that the engine is aligned properly? Also, make sure the water fitting is working and not blocked, if you have one?

 

[O C Diver]

Is there a water feed to the stuffing box?

Ted

 

[wpc691]

No water feed. I’ll study it again in the morning, but like most other things, it looks like I have to disassemble half the engine to get at all the bolts holding the coupling together.

 

[High Wire]

One drop per minute drip from the packing is too tight unless it is a dripless packing. One drop per 5 - 15 seconds is normal for normal packing.

 

[catalinajack]

Not for modern packing like Gore-tex!

One drop per minute drip from the packing is too tight unless it is a dripless packing. One drop per 5 - 15 seconds is normal for normal packing.

 

[O C Diver]

No water feed. I’ll study it again in the morning, but like most other things, it looks like I have to disassemble half the engine to get at all the bolts holding the coupling together.

I think I would start by loosening the packing up significantly and then trying turning the shaft. With a good alignment and everything else ok, you should be able to grap the shaft and turn it. If not, trying turning the coupling. I would want to eliminate the packing as the problem before getting further into disassembling things.

Ted

 

[wpc691]

I think I would start by loosening the packing up significantly and then trying turning the shaft. With a good alignment and everything else ok, you should be able to grap the shaft and turn it. If not, trying turning the coupling. I would want to eliminate the packing as the problem before getting further into disassembling things.

Ted

I backed the nuts all the way off the gland. It maybe got a little easier, but still much harder to turn than the other shaft. The diver turned it by hand holding the prop, but no way I could turn it from inside holding the shaft - I needed a strap wrench to turn it. It did turn smoothly, no binding, but not easy to move.

 

[Larry M]

Not for modern packing like Gore-tex!

What he said. If we get several drops an hour it’s too loose.

GFO - GFO Packing

 

[O C Diver]

I backed the nuts all the way off the gland. It maybe got a little easier, but still much harder to turn than the other shaft. The diver turned it by hand holding the prop, but no way I could turn it from inside holding the shaft - I needed a strap wrench to turn it. It did turn smoothly, no binding, but not easy to move.

Have you ever repacked the stuffing box in the water? I haven't and I'm not suggesting if you haven't done it, you should be comfortable doing it. But, if you have and you're comfortable doing it, I would move there next. Packing is inexpensive. If I were comfortable doing it, I would want to dig the old packing out and see what's left of it. If the shaft doesn't turn as well as the other one, you're probably going to be pulling the boat out next.

Ted

 

[High Wire]

Not for modern packing like Gore-tex!

Agree but nothing in the OPs posts say anything about goretex.

 

[slowgoesit]

OP, just for clarification, you state:

Saw the shroud on the stuffing box on the port shaft pulsing up and down about 3/16”

What was the SHAFT doing at that time? Was it displaying any sign of vertical/lateral movement at all?

 

[wpc691]

OP, just for clarification, you state:

Saw the shroud on the stuffing box on the port shaft pulsing up and down about 3/16”

What was the SHAFT doing at that time? Was it displaying any sign of vertical/lateral movement at all?

Obviously harder to see exactly what the shaft was doing, but it had to be moving up and down in concert with the shroud/stuffing box...didn’t it? Unless the packing (done before I bought the boat, don’t know what it is) somehow folded over on itself (as has been described to me re the rubber in the cutlass bearing) and was rolling around driving the stuffing box up and down like a cam?

 

[Irish Rambler]

I can only speak from experience. The P.O had overtightened the stuffing box so many times instead of repacking it and it caused light grooves on the shaft. When I lifted it out I could see the discolouration where it had been overtightened causing running too hot/ overheating.
I was lucky that I could turn my shaft end over end and took the opportunity to fit a PSS seal instead of a stuffing box. I can only say from thousands of miles that they're the best thing since sliced bread and I highly recommend them.
Others may have a different view but for me the PSS seals are the dogs gonads.

 

[wpc691]

Have you ever repacked the stuffing box in the water? I haven't and I'm not suggesting if you haven't done it, you should be comfortable doing it. But, if you have and you're comfortable doing it, I would move there next. Packing is inexpensive. If I were comfortable doing it, I would want to dig the old packing out and see what's left of it. If the shaft doesn't turn as well as the other one, you're probably going to be pulling the boat out next.

Ted

See my response above re the packing. I wasn’t thinking of doing that, but I am now. I’ve never packed a stuffing box at all, much less in the water, but it looks relatively straightforward, and I have a buddy who has done it. Between the two of us, I’m sure we can get it done...of course, there’s social distancing to deal with.

 

[syjos]

Does the sound go away when you increase RPM?

If the sound is at the lower RPM range and goes away with increased RPM, the cause might be a "singing" prop. A prop shop can file an anti-sing edge on the prop tips.

 

[wpc691]

Does the sound go away when you increase RPM?

If the sound is at the lower RPM range and goes away with increased RPM, the cause might be a "singing" prop. A prop shop can file an anti-sing edge on the prop tips.

Never increased rpm’s beyond 800. Sound occurred 3 times, then I saw stuffing box hopping up and down and shut down...I had visions of the shaft log hose ripping.

 

[kchace]

The fact that the shaft is very hard to turn combined with the up and down movement you saw definitely indicates some kind of problem and not with the shaft packing. The advice to disconnect the coupler is a good next step. Then you can tell if it’s the shaft (my guess) or on the transmission side. I can think of no way the shaft packing can cause this. I also believe the leaking shaft packing was a symptom of all the movement, not any part of the cause.

Needing a strap wrench to turn the shaft is a very bad sign. I suggest separating the shaft coupling and then rotating the shaft to help narrow down the cause. If the shaft is still very hard to turn you at least have a severe alignment issue or possibly a bent shaft.

Ken

 

[O C Diver]

See my response above re the packing. I wasn’t thinking of doing that, but I am now. I’ve never packed a stuffing box at all, much less in the water, but it looks relatively straightforward, and I have a buddy who has done it. Between the two of us, I’m sure we can get it done...of course, there’s social distancing to deal with.

There will be some amount of water coming in when you dig out the old packing. To get an idea of what to expect, determine how far below sea level the stuffing box is. A foot below the surface will have X amount of water coming in. At 2' it will double. 3' will triple the flow. The pressure of the water is very low (.5 PSI per foot). So have several old towels to wrap around the tube and shaft with some zip ties. If things go bad, wrapping a towel or 2 and securing with zip ties should reduce it to a manageable leak. Check your bilge pumps before you start. I would consider lining up the travel lift, just in case.

If you have a roll of rescue tape, that would work well also.

Ted

 

[firehoser75]

To me, it is very brave, and a bit risky to repack in the water. Risk vs reward just doesn't seem to be there in this case.
I am far from an expert on this, but I think what Ken said a couple of posts back makes sense. Therefore, you will have to haulout anyway. Why not first, then investigate causes. In that way, no big water leak with possibly a mad dash to the haulout . Just an opinion, but I am a bit conservative.

 

[High Wire]

I can’t see the stuffing box moving without the shaft moving. That means the coupler and transmission moving. Which could mean the rear motor mounts are shot.

 

[syjos]

Repacking in the water is not that dangerous.

Cut enough packing material, test the bilge pumps before starting and it should be stress free.

First time I changed packing in the water was with the Mainship 34. Had everything ready, pulled out the old packing and the new packing was the incorrect size. Oops!

Stuffed rags around the shaft, wrapped duct tape around the rags and installed hose clamps over everything. Raced to the nearest marine chandlery, purchased the correct size packing and raced back to the boat with visions of a sunk boat. Boat was fine and installation of the packing went smoothly. Only glitch was cutting away all the duct tape ang rags wrapped around the shaft!

 

[mike50]

If you have Detroit’s and Allison gears you might also want to look at the motor mounts. Sometimes the old Detroit version motor mounts will sag over time causing high axial shaft loading on the trans and cutlass bearings. As already suggested decouple the shaft flange from the trans and check for droop and ease of rotation.

 

[wpc691]

If you have Detroit’s and Allison gears you might also want to look at the motor mounts. Sometimes the old Detroit version motor mounts will sag over time causing high axial shaft loading on the trans and cutlass bearings. As already suggested decouple the shaft flange from the trans and check for droop and ease of rotation.

Cat 3208’s, Twin Disc MG506

 

[Steve DAntonio]

Disconnect the coupling and turn the shaft by hand. That may give you a better idea, then check that the engine is aligned properly? Also, make sure the water fitting is working and not blocked, if you have one?

Actually, you should not disconnect the coupling to carry out this test, you want to replicate as closely as possible actual operating conditions. The transmission should impart virtually no drag. It's hard to quantify the effort required to turn a shaft, it's variable depending on the size of the shaft and prop, number of bearings, stuffing box type and tension for conventional etc. Suffice it to say, you should be able to turn most shafts by hand, even if it takes a lot of effort, if you can get a good purchase on the coupling, from inside most small boats, if something isn't amiss.

 

[twotoots]

Tranny fluid

Check the tranny fluid, look for anything that might suggest a bad output shaft bearing. Might let the thing idle out of gear for a long while and see if the noise is any more frequent after it gets hot.