Chatter/Rattle coming from Alpha 1 Gen II

Jiminthekeys

Petty Officer 3rd Class
Joined
Aug 7, 2012
Messages
83
Re: Chatter/Rattle coming from Alpha 1 Gen II

I checked the prop and the hub does not look damage and I don't seem to loose any power or speed when this happens. I'm kind of leaning now towards a possible loose flywheel or loose engine coupler but I want to be super sure before I hook the davit up to the motor and pull it out... Man, I have never really dealt with anything this difficult to diagnose, it is driving me nuts!:frusty:
 

buzzm19

Petty Officer 2nd Class
Joined
Dec 14, 2009
Messages
152
Re: Chatter/Rattle coming from Alpha 1 Gen II

Jim, I am at a loss about your noise, I would suggust that you take the outdrive off and you will see the water inlet in the transom, have someone hold a water hose to it so that you can start the motor without the outdrive on (the water pump on the motor will feed the motor) and see if any thing is different. I am thinking that any movement with your outdrive seems to create the problem and the noise may still be there at slower speeds only to the point that it is not loud enough for you to hear it (engine noise, ex,ect). This way you can at least narrow down the source. I didn't hear anyone mention checking the alinment on your coupler and gimble bearing? Your alinment could be off, the gimble bear could be cocked and any time you replace the gimble bearing the alinment should always be checked. look at the outdrive shaft for any marks or shiny spots,make sure that the two o rings are in good shape (if they are missing or damaged that could be your problem). If they are missing than thats your problem. My guess is what your looking for is something binding and it gets more agrivated under torque to the point you hear it. I hope this helps Buz
 

Jiminthekeys

Petty Officer 3rd Class
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Aug 7, 2012
Messages
83
Re: Chatter/Rattle coming from Alpha 1 Gen II

Thanks for your suggestions Buzz. The alignment was checked before and after GB replacement and was good. I will check the seals you mentioned on the shaft though. Keeping my fingers crossed it may be as simple as that. Your suggestion on the water hose and running is good however I cannot get this noise to produce unless it is under a load around 4000 RPM or trimming up at all under the same load. I tried my hardest to get it to produce at the dock and on muffs and can't so I don't think the hose method would help any.

Do I have to drain the drive lube prior to pulling the drive? Or just empty the monitor bottle. (Don't want a mess and I don't really want to refill it with new oil since it just got changed).
 

Speakrdude

Ensign
Joined
Feb 25, 2004
Messages
942
Re: Chatter/Rattle coming from Alpha 1 Gen II

You do not have to drain the drive lube. Not even the bottle. (Unless your splitting the drive apart)
There is a valve that will shut off the lube to the drive when you pull it. Maybe get a drop or to on the driveway.
 

Speakrdude

Ensign
Joined
Feb 25, 2004
Messages
942
Re: Chatter/Rattle coming from Alpha 1 Gen II

I listened to your video again, and while it's hard to hear everything due to the wind noise, It sure sounds like when you hit the magic spot, the rpms suddenly increase. May try to video your tach while gently accelerating to the spot, and watch what happens. It kind of sounds like a prop slip, causing cavitation which, in turn is causing something to rattle.
 

Jiminthekeys

Petty Officer 3rd Class
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Aug 7, 2012
Messages
83
Re: Chatter/Rattle coming from Alpha 1 Gen II

Bondo those champion plugs were only about 6 months old. They only got maybe 3 or 4 outings on them and then this all happened and boat was down for sometime waiting for my mechanic to change the GB, unis, and bellows.
 

midcarolina

Chief Petty Officer
Joined
Jul 16, 2013
Messages
631
Re: Chatter/Rattle coming from Alpha 1 Gen II

There are many here that are superior mechanics than me......... but when I listen and watch closely to the "noise " video I can clearly see the tach jump up when the noise occurs...... I think its got to be prop slip or coupling issue...

Any chance someone could have done a midnight prop swap on your boat?
 

Jiminthekeys

Petty Officer 3rd Class
Joined
Aug 7, 2012
Messages
83
Re: Chatter/Rattle coming from Alpha 1 Gen II

nope, same prop. I had run over a sandbar a few trips before this all started but the hub on the prop looks undamaged. Maybe i'll press it out and take a better look at it. But the edges look fine with no signs of slippage.

The RPM's sometimes jump but more times than not stay steady. I guess it would't hurt to change the prop or hub or both out before i dive in and pull the engine. Someone on another forum suggested I may have a crack somewhere in the flywheel cover that could cause vibration I will try and follow as much of the cover with my hand and check that out as well...

Thank you all for the help thus far. I believe more heads are better than one in diagnosing hard to find problems!
 

UncleWillie

Captain
Joined
Oct 18, 2011
Messages
3,995
Re: Chatter/Rattle coming from Alpha 1 Gen II

nope, same prop. I had run over a sandbar a few trips before this all started but the hub on the prop looks undamaged. Maybe i'll press it out and take a better look at it. But the edges look fine with no signs of slippage...

Place a mark on the prop and the hub.
After the next run, if the marks are not still aligned, something slipped.
 

Speakrdude

Ensign
Joined
Feb 25, 2004
Messages
942
Re: Chatter/Rattle coming from Alpha 1 Gen II

Nice tip Uncle Willie. Never thought about trying that. (seriously)
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,344
Re: Chatter/Rattle coming from Alpha 1 Gen II

cracked flywheel dust cover has possabilities
 

Jiminthekeys

Petty Officer 3rd Class
Joined
Aug 7, 2012
Messages
83
Re: Chatter/Rattle coming from Alpha 1 Gen II

Just out of curiosity what would cause the flywheel housing to crack?
 
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