Some driveline vibration - where to start?

[Z71_Silvy]

Last summer I replaced my shaft seal on my 2005 Prostar 197TT. It was leaking bad and was quite worn out. I successfully replaced it and aligned the engine with the shaft. Afterwards, I noticed that there is a noticeable vibration just above idle and around 23ish MPH. Outside of that, the drivetrain is pretty smooth but not glass smooth. There is no vibration when revving in neutral.

I am not sure where to start. Is the shaft bent (expensive), is the strut bent (also expensive), are the cutlass bearings shot (not expensive). Is there a way to check some things before getting too deep into this? I am fairly handy and can handle a lot of this. I also understand the concept that you align the engine to the shaft and not vice versa. I don't believe it is the propeller but again, how would one check to ensure it's balanced?

But what are some things (if any) that I can do without taking everything apart to try and narrow things down? What would cause vibration like this? Could it be as simple as the cutless bearings? How would I check those? I can't imagine it's something major as it tends to be smoother outside of those two areas.

Some history: I have owned the boat since April of 2017. I bought it with about 425 hours on it and now have 880 hours on it. I believe the prop is original...or it was replaced with the exact prop that came from the factory. I have "hit" (struck) one thing in my time owning this boat. One of the blades hit a rock as I was drifting to shore. The prop was not spinning nor was the engine running at the time. One blade was damaged. It wasn't a hard hit. Aside from that, I've been pretty lucky but also only boat known waters.

Thanks,

-Matt

[bturner2]

I'm sure everyone will have their own take on this, this will be mine.

Low hanging fruit is the prop. Any chance getting another to test with? With prop repair it's pretty much luck of the draw with the local shop. some are outstanding, others.... well not so much. I always send my OJ's back to Eric at OJ to make sure what I get back is as close to new as possible.

Cutlass bearing would be next (past doing a visual on the strut). You should be able to do an inspection on this, then grab the prop and try to move the shaft side to side looking for slop in the bearing area while doing so. Movement should be minimal. Also look to see if the bearing is wearing evenly.

Check the alignment again. This is critical and needs to be right.

Honestly, my money would be on the prop.

[robadele]

Agree with bturner2, start with the prop. Cheapest and easiest place to start. Also the most likely.

[CantRepeat]

Prop is the place to start and OJ does great work.

You can also take a photo form behind the boat and show the prop and the strut. Sometimes it's easy to identify a bent strut.

[88 PS190]

Prop check is good there is actual balance but also assymmetry between blades that can occur.

But its worth checking a few things, worn out shaft seals can be a sign that the shaft was either bent, maligned, or bearings could be bad. Wiggle the shaft?

You can use a dial indicator to check for wobble in the shaft - or alternatively clamp something like a paint stirrer stick to the strut so its close to the prop and just turn the prop and look for blade wobble.

[jpwhit]

Your description implies, that the vibration started immediately after you replaced the shaft seal and re-aligned the engine. Perhaps I'm reading it too literally, but if you didn't have vibration, then you did that work and the vibration appeared. Then I would suspect the alignment isn't right. And that can certainly cause a vibration.

If it is a more general vibration not directly associated with that work, then like others have said always start with the prop. Especially if there has been contact with anything in the past. Personally, I'd just buy a new prop from OJ and then they will rebuild the old one for free. Use the old one as your backup prop. More often than not, a rebuilt prop won't be as smooth as a new prop. If you simply send the old prop for a rebuild, you still won't know for sure if the rebuilt prop has a vibration or if you have another drive-line issue. A new prop is always the best way to eliminate the prop as a source of vibration.

[Z71_Silvy]

Thank you for the response so far. This will give me some things to check out before I start throwing parts at it.

Your description implies, that the vibration started immediately after you replaced the shaft seal and re-aligned the engine. Perhaps I'm reading it too literally, but if you didn't have vibration, then you did that work and the vibration appeared. Then I would suspect the alignment isn't right. And that can certainly cause a vibration.

If it is a more general vibration not directly associated with that work, then like others have said always start with the prop. Especially if there has been contact with anything in the past. Personally, I'd just buy a new prop from OJ and then they will rebuild the old one for free. Use the old one as your backup prop. More often than not, a rebuilt prop won't be as smooth as a new prop. If you simply send the old prop for a rebuild, you still won't know for sure if the rebuilt prop has a vibration or if you have another drive-line issue. A new prop is always the best way to eliminate the prop as a source of vibration.

There we’re a lot of things that occurred after I lightly bent the blade drifting into shore. I did have the prop fixed and that’s the one I’m using now. I did try a highly recommended ACME but I felt the driveline vibration was worse with that prop than the original. So I sent it back.

But the vibration was there prior to doing the shaft seal. So my brain then wants to figure out why the shaft seal wore out. Is it because the something in the driveline is out of whack or is it old age? I think I will have the prop shipped to Eric at OJ props and have them check the balance on it. While that’s being addressed I’ll look at some of the other basic items and see what I can figure out

[waterlogged882]

Thank you for the response so far. This will give me some things to check out before I start throwing parts at it.




There we’re a lot of things that occurred after I lightly bent the blade drifting into shore. I did have the prop fixed and that’s the one I’m using now. I did try a highly recommended ACME but I felt the driveline vibration was worse with that prop than the original. So I sent it back.

But the vibration was there prior to doing the shaft seal. So my brain then wants to figure out why the shaft seal wore out. Is it because the something in the driveline is out of whack or is it old age? I think I will have the prop shipped to Eric at OJ props and have them check the balance on it. While that’s being addressed I’ll look at some of the other basic items and see what I can figure out

Lots of good information in the thread.

Another take on DIY visual exam; I am leaning toward the coupling alignment...hear me out: I could easily be wrong.

I have read everything above and realize you feel you have covered all the bases. Aside from the prop possibility, check your alignment (again) between the two flanges. Should be 0.003" -0.003 / +0.000. Here's the tell tale observation; loosen all four machine screws and remove them. Stop right there. Conscientiously observe the shaft flange as you pull it back out of the transmission flange. That is a male / female joint, respectively. If the shaft moves in any direction in an obviously significant amount, there lies a problem. You need to re-align. At the time (de-coupled) make sure the shaft is near center of the shaft log and not in a bind. Then align the flanges accordingly. All of this can be done non-destructively, easily with patience and will eliminate or confirm that much of your drive line.

If the shaft flange moves freely in and out and your feeler gauge says OK, just bolt it back up. No harm, no foul, no extra work aside from four machine screws.

As to your prop... If it has one slight, minor, tiny ding in any blade, it becomes suspect and likely. When a prop is repaired, it is laid into a block (template) and re-conformed to that block, then balanced in one of several ways. With the Acme prop, all the more for me to think alignment. Those are top notch CNC finished props. I find it hard to believe the Acme was the issue...just saying. I run the 541 with all good results.

Back to the alignment...re-check the alignment when you get the flanges apart. The shaft flange should easily and freely slide back into the transmission flange. With all bolts out (or loose) strive to get the aforementioned setting and tolerances. If that is not the problem, all the better. You now have a re-confirmed alignment and can focus on the cutlass bearings (worn from age and maybe some drifted misalignment in the strut). The entire process of shaft disassembly, and strut bearing rebuild is so simple and can all be accomplished within one day's time for a new baseline of drive line and prop. Don't hate the Acme.

Best on the solution.

US $0.02

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[Z71_Silvy]

Thank you Waterlogged. I've learned over the years to listen when you talk. I will follow your advice tomorrow and re-check the alignment.

I did take some pictures today of everything under the boat. Everything looks good. The shaft spins fairly easily one-handed (even on the smooth part). I did not feel any binding at all.

The strut looks to be in great shape but it doesn't seem to be directly in line with the rudder. I'm not sure if this is normal but my simplistic brain tells me they should be in line. Doing some very rudimentary measuring, it seems the strut is 1/4" off side to side.

Anyway, I took some pictures, maybe something will jump out to you guys that I am not seeing. I'm also in contact with OJ Props to get my propeller balanced.

[waterlogged882]

Thank you Waterlogged. I've learned over the years to listen when you talk. I will follow your advice tomorrow and re-check the alignment.

I did take some pictures today of everything under the boat. Everything looks good. The shaft spins fairly easily one-handed (even on the smooth part). I did not feel any binding at all.

The strut looks to be in great shape but it doesn't seem to be directly in line with the rudder. I'm not sure if this is normal but my simplistic brain tells me they should be in line. Doing some very rudimentary measuring, it seems the strut is 1/4" off side to side.

Anyway, I took some pictures, maybe something will jump out to you guys that I am not seeing. I'm also in contact with OJ Props to get my propeller balanced.

The strut will be off-center a little...common characteristic of the inboard setup. Photos look OK as well. It appears from the photos that you are narrowing down some of the possibilities.

Your strut bearings look just fine to me.

Best on the solution.

.

[Z71_Silvy]

Ok so I lied. I did the majority of the alignment this afternoon. I got it between .002 and .0025. If I try for any more I’m going to go insane. What a pain!

[sand2snow22]

Let us know anymore vibration? Alignment, prop, strut and driveshaft. Many moons ago we aligned a motor to a bent driveshaft but if vibrated from idle to WOT

[Z71_Silvy]

Let us know anymore vibration? Alignment, prop, strut and driveshaft. Many moons ago we aligned a motor to a bent driveshaft but if vibrated from idle to WOT

My boat was butter smooth at idle. And various points in the RPM range. But then other points had more vibration than I’m comfortable with.

I don’t think I’ll be able to get it tested before the prop goes. We have had anywhere between 2” and 10” of rain over a wide swath of southern MN. As a result the St Croix River is rising. By about 6pm tomorrow, the St Croix will be above 83’ in Stillwater MN which means the entire river is no wake. Crest should be around 86’ but will be there for a bit. I could do the Mississippi but I’m sure there will be a lot of debris floating.

So it will be a while before I can test the alignment. But I want to get the prop sent to OJ Props to be correctly balanced. Or at least checked to ensure it’s balanced by the peeps who made the thing.

[waterlogged882]

Ok so I lied. I did the majority of the alignment this afternoon. I got it between .002 and .0025. If I try for any more I’m going to go insane. What a pain!

That's good. You're there. I'd run with it. Best on the boating season. Endure the water deluge. Better to have water than not.

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[motomario]

Thank you Waterlogged. I've learned over the years to listen when you talk. I will follow your advice tomorrow and re-check the alignment.

I did take some pictures today of everything under the boat. Everything looks good. The shaft spins fairly easily one-handed (even on the smooth part). I did not feel any binding at all.

The strut looks to be in great shape but it doesn't seem to be directly in line with the rudder. I'm not sure if this is normal but my simplistic brain tells me they should be in line. Doing some very rudimentary measuring, it seems the strut is 1/4" off side to side.

Anyway, I took some pictures, maybe something will jump out to you guys that I am not seeing. I'm also in contact with OJ Props to get my propeller balanced.

Everything are looking Good! Prop balanced need only!