Cutlass Bearing on Prop Shaft Stops Motor

[senormechanico]

Put in a PSS shaft seal and be done with it.

[skipmac]

Originally Posted by Marpessa

I hope that explains it as to your Question

Perfectly. However, don't have any better guess as to what's going on.

Originally Posted by Marpessa

It will run for a couple minutes, 1:30 or so, then you can hear the motor load up and the shaft kinda seems to vibrate more, and if you crank up rpms it will really vibrate and stall motor.

If you just leave at the rpm level when you hear it start to struggle and load up it will just kill the motor pretty quick, but when you hear it load up and shift into neutral real quick you can save it from stalling...

OK. So you shift to neutral and the engine will keep running. Can you turn the prop shaft by hand at this point?

How long do you have to wait before it will turn again? Once the appropriate time has passed can you just crank it back up, put it in gear and it runs just fine for another minute or so?

Sounding more and more to me like it's not the stuffing box. I would think that if the stuffing box was binding up enough to stop the shaft then you would feel heat, a lot of heat. I'm guessing something before or after the stuffing box, either the transmission or something like monofilament around the prop. Do you have a shaft strut or shaft shorter and only projects a short distance from the hull?

I do agree that you could be tearing something up by doing this. Maybe not but???

[UNCIVILIZED]

Are there any signs of twisting on the hose which runs between the stuffing & where it meets up with the hull exit fitting? Also, have you looked everything over for some grease zerks which may have gone unattended for way too long? And these could be possibly anywhere in the drive train.

And yeah, I'd be more than a little averse to running it until the problem was figured out. With the exception of trying the already mentioned trick of running the engine with the shaft disconnected. If it's still exhibiting the same symptoms then, it'd make me think transmission.

[shakey doug]

Graphite packing should not use on a s/s shaft in salt water It is way to noble galvanic action will occur.

[River Cruiser]

Unbolt the shaft coupling and start the engine and put it in gear. If it bogs down and dies I would look at the Trans, if it's hydraulic both sets of clutch packs may be locking up. If it doesn't die then it's something with the cutlass bearing or something on the shaft such as rope or heavy fishing line. I have seen the control valve on power shift transmissions bypass oil and try to lock up a extra clutch pack causing a problem similar to yours, if it's not a hydraulic Trans then that won't be your problem. Good luck


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[Rapscallion]

Originally Posted by Marpessa

It will run for a couple minutes, 1:30 or so, then you can hear the motor load up and the shaft kinda seems to vibrate more, and if you crank up rpms it will really vibrate and stall motor.

If you just leave at the rpm level when you hear it start to struggle and load up it will just kill the motor pretty quick, but when you hear it load up and shift into neutral real quick you can save it from stalling...

I hope that explains it as to your Question

Fuel filter been changed lately?
I would try that before digging too deep.

D.

[Marpessa]

Yep, diver said wait till tomorrow he'll bring his camera and we'll see what's going on below the WL.

Engine mounts and alignment seem all good - never a problem before and nothing has changed.

I used a mirror to see that all former flax was removed. Scraped it with a pick it's all bronze in there.

All testing has been done while tied up at the dock. I left once, but turned around because I didn't trust it. I can rev her up for a short period, but the end result is always the same.

As I said, it will run, at low rpm for a short period. Cross that threshold or rev it up and something binds it up we lose power until a stall. Put it in neutral and it fires right up.

As a footnote on the fuel question, I did just totally redo the entire system from the tanks to the motor. I'll put some pics up here.

[Marpessa]

This is better...

[Marpessa]

Originally Posted by shakey doug

Graphite packing should not use on a s/s shaft in salt water It is way to noble galvanic action will occur.

Good to know. They sell it at WM here and there's not a lake in sight. Guess the neighbor could still have a ski boat though...

[Marpessa]

@uncivilized
@River cruiser

Yes the hose seems to shake and vibrate that is around the propshaft with hose clamps. That's why I think the cutlass is the problem. But, if vibration were coming from the other end I could have miss diagnosed - will look closer tomorrow when diver comes.

I can't uncouple the trans from shaft the bolts are rusted we'll be cutting it off in the yard next month.

It's not fishing line, unless diver missed it - we'll find out tomorrow.

I'll ask my mechanic about the hydraulic transmission possibility and we'll start working it from that end.

[Rapscallion]

Originally Posted by Marpessa

This is better...

That is taking a filter change to the next level! nice job.

The symptoms just sounded consistent with a fuel delivery problem.

Good luck

D.

[Marpessa]

@Rapscallion

We had some trouble there. Maybe still haven't fixed it. Damn that's a whole different troubleshoot than where I thought I was. Fuel system has had real trouble staying stable and bleeding has been tough, but once it got running I never thought there may still be a vacuum problem. Will check and advise...

[Pelagic]

Originally Posted by Marpessa

.....can't uncouple the trans from shaft the bolts are rusted we'll be cutting it off in the yard next month.

It's not fishing line, unless diver missed it - we'll find out tomorrow.

I'll ask my mechanic about the hydraulic transmission possibility and we'll start working it from that end.

If you dont get a confirmed answer tomorrow that the problem is on the prop end, I would rethink the timing on fixing the coupling, so that you can trouble shoot.

[skipmac]

Originally Posted by Marpessa

Good to know. They sell it at WM here and there's not a lake in sight. Guess the neighbor could still have a ski boat though...

Sorry but I have to object to this. Graphite packing is the recommended product for boats in salt water. Yes technically graphite is a good bit higher on the galvanic scale that SS but have not heard of any problems in this application.

Here's a link for photos, step by step on installing new packing by forum member Maine Sail. He recommends using Gore GFO packing.

Re-Packing A Traditional Stuffing Box Photo Gallery by Compass Marine How To at pbase.com

[a64pilot]

Did this trouble start at the same time you finished re-doing your fuel system?
Have you ever had it out under power with this new fuel system? It could be fuel starvation, if there is a restriction in the fuel system, it would be difficult to bleed and may well run just fine with low fuel flow, but when under power, fuel demand may exceed fuel flow available and it would act like you describe. Could be as simple as a kinked fuel line. ( I hope)