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Vibration at 1/3 to half throttle & none at idle or full


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Hey guys & girls,

over the last few days i have been reading the prop and shaft threads, but I haven't found one that is exactly my issue.

So here is what happed:

I was cruising the lake a few days ago late at night at idle speed and I hit a stump or something hard at the bottom of the lake.

I was a good boater and shut it down right away, jumped in swung the boat around and went back the way i came.

after I took a nice long ride at idle back to the lift (not by choice), i put her up and inspected the prop.

I saw a couple little maybe 1/16 inch dimples, but i would call them hits like i used to get on my I/O if i hit something.

So I took her out and put a little gas to her. she's fine at idle, and fine at full speed, but i have this vibration at 1/3 to half now. pretty much while she is off plane.

So I took her back, reinspected, and still didn't see anything. however, I did get under there and manhandled the prop a bit. it has a very very small amount of play. Could it be the shaft?

Now on my I/O i never had any. does the same rule apply here... as tight as you can physically get it?

Also, it made me realize I really need a spare prop because trouble shooting would have been much easier.

I don't slalom ski a lot anymore, but still do a few times a year. I mostly use the boat for wakeboarding and tubing.

Would you guys go 3 blade or 4 blade and what brand?

does anyone make a stainless prop for an inboard?

1989 Sunsetter euro F-3 less than 400 hours and runs like a top.

I will post Prop Pictures tonight.

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You probably need to go into more detail on what you mean by "very small amount of play". Look for run-out on the dimple at the end of your drive shaft.

You want a nibral (nickel, brass, aluminum alloy) prop (probably a 4 blade but call Acme of OJ) because it's softer and theoretically will fail before the rest of the more expensive harder components get damaged.

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By small amount of play, i mean i can feel a slight movement in the prop on the shaft if i really work at wiggling it with both hands on a blade.

I heard about the Black dot method for run out....

Am I looking to see if that dot isn't staying centered?

is there a better way to go about this?

If this is the case, is it new shaft time?

Edited by jeepdude2
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By small amount of play, i mean i can feel a slight movement in the prop on the shaft if i really work at wiggling it with both hands on a blade.

I heard about the Black dot method for run out....

Am I looking to see if that dot isn't staying centered?

is there a better way to go about this?

If this is the case, is it new shaft time?

Standard checks are these:

Turn the prop and if the shaft ihas any resistance or binds up in any way then you need to check your shaft and strut

The strut also has a shaft bearing, too much play could also do what you describe

Borrow a prop or put your spair on. If the issue goes away with the other prop, well it is the prop

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By small amount of play, i mean i can feel a slight movement in the prop on the shaft if i really work at wiggling it with both hands on a blade.

I heard about the Black dot method for run out....

Am I looking to see if that dot isn't staying centered?

is there a better way to go about this?

If this is the case, is it new shaft time?

Take the prop off and inspect the key. It might be damaged. When you say a little play, is it the prop loose on shaft or is the prop and shaft loose. If its the latter check your strut bearing it might be worn or damaged. Lastly check the drive shaft. You might want to check the coupler bolts to the transmission to make sure all are there and tight.

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the strut bearings are rubber so there will be and should be a small amount of movement in the shaft your viberation is probably your prop i had one small nick in a prop and every thing looked fine but the hole blade of the prop was actually pushed slightly just enough to make a vibration

Ken

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Standard checks are these:Turn the prop and if the shaft ihas any resistance or binds up in any way then you need to check your shaft and strutThe strut also has a shaft bearing, too much play could also do what you describeBorrow a prop or put your spair on. If the issue goes away with the other prop, well it is the prop

Take the prop off and inspect the key. It might be damaged. When you say a little play, is it the prop loose on shaft or is the prop and shaft loose. If its the latter check your strut bearing it might be worn or damaged. Lastly check the drive shaft. You might want to check the coupler bolts to the transmission to make sure all are there and tight.

the strut bearings are rubber so there will be and should be a small amount of movement in the shaft your viberation is probably your prop i had one small nick in a prop and every thing looked fine but the hole blade of the prop was actually pushed slightly just enough to make a vibrationKen

Thanks for all the help so far guys.

I had my dad come over and take a ride yesterday and he thinks it is just a prop issue, but he is an outboard guy.

So compared to an outboard how freely should everything turn in neutral?

there is more resistance than on a outboard because your direct to the tranny right?

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By small amount of play, i mean i can feel a slight movement in the prop on the shaft if i really work at wiggling it with both hands on a blade.

I heard about the Black dot method for run out....

Am I looking to see if that dot isn't staying centered?

is there a better way to go about this?

If this is the case, is it new shaft time?

Amatuers can set up a lazer pointer to aim at the dimple to look for run out. I don't think even the slightest amount of "wiggling" is normal and probably the cause of your vibration, I would start looking into the strut and verifying the coupling bolts are tight.

Edit- if Khelfrich is correct then disregard, but I don't recall any play at all in mine :dontknow:

Edited by Ndawg12
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Amatuers can set up a lazer pointer to aim at the dimple to look for run out. I don't think even the slightest amount of "wiggling" is normal and probably the cause of your vibration, I would start looking into the strut and verifying the coupling bolts are tight.

Edit- if Khelfrich is correct then disregard, but I don't recall any play at all in mine :dontknow:

Well when i get home today, i will snap some photos of the prop and take the water pump belt off and dry run for a minute and see what i can see in the shaft with a black dot.

Do you know how easy it should be to spin the shaft in neutral?

is it going to be resistive, but i am just looking for no bind?

or should it spin freely like an I/O or outboard?

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Well when i get home today, i will snap some photos of the prop and take the water pump belt off and dry run for a minute and see what i can see in the shaft with a black dot.

Do you know how easy it should be to spin the shaft in neutral?

is it going to be resistive, but i am just looking for no bind?

or should it spin freely like an I/O or outboard?

It should not spin freely. There will be some resistance but should also not bind.

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I have seen 3 cases of vibration like you described. Each time it has been from dings and/or bends in the prop. They replaced the prop, immediately the vibrations went away.

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I have seen 3 cases of vibration like you described. Each time it has been from dings and/or bends in the prop. They replaced the prop, immediately the vibrations went away.

Ryan,

I think after many chats today you are right and it is the prop.

Anyone with a inline drive have a preference on prop?

I am considering either an OJ 4 blade or an acme 3 blade.

from what I have read I think the OJ 4 blade is the way to go, but I was looking for a few opinions.

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Alright guys,

I got under the boat last night and spun the shaft.

It took a lot of effort to turn, but i didn't feel any spot where it was harder to turn than others.

Is it normal to take significant effort to turn one of these?

NYRyan,

were the dings you speak of as small as the ones I described?

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It should take a lot of effort to spin the prop. I had the same issue when I purchased my boat a few years back. Vibration at mid range speeds only. I made a call to Acme props and that was the fix.

Good Luck

CB

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Alright guys,

I got under the boat last night and spun the shaft.

It took a lot of effort to turn, but i didn't feel any spot where it was harder to turn than others.

Is it normal to take significant effort to turn one of these?

NYRyan,

were the dings you speak of as small as the ones I described?

When on the trailer and dry it takes me two hands to turn mine and always has since new. WD40 on the cutlass bearing makes it turn much easier, water will as well.

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Good news jeepdude 2.....

Yes,

most likely Having a new Prop delivered sometime next week and the original re-tuned.

That is my plan at least...

Just have to decide on the Acme or the OJ. leaning towards the OJ though, I'd like to try a 4 blade.

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Yes,

most likely Having a new Prop delivered sometime next week and the original re-tuned.

That is my plan at least...

Just have to decide on the Acme or the OJ. leaning towards the OJ though, I'd like to try a 4 blade.

Nice...

Let me know what you end up doing and how it works out. We need to hook up and get our boats together sometime.

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How freely should the shaft turn when the boat is in neutral??

Should it just spin like it would on an outboard?

In neutral the shaft/prop should not turn.

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