5.7 alpha 1 vibration

[rthomas]

The boat in my sig has a slight vibration, its always had this, in gear out of gear most noticable @ 1k-2k its gotten a little worse in the last 600 hrs. Ive had the drive off 5 or 6 times and the u-joints have always been good, could it be the coupler? at its worst it compares to reving a motor with a miss, but I know thats not it.

 

[redjmp]

Re: 5.7 alpha 1 vibration

Myself, I would start by pulling and reading the plugs.
Then I would do a compression test.
Then a spark test.
If I still wasn't sure, I would pull the valve covers and measure the valve travel as it might be a worn lobe on the cam...

 

[GLENN M]

Re: 5.7 alpha 1 vibration

pull the drive run motor see if you still have vibration
help narrow it down

 

[rthomas]

Re: 5.7 alpha 1 vibration

Last spring when I had it out of the water I did run it with the drive off, the motor is not the problem, Ive also replaced the gimbal bering twice in the last 600 hrs and that has had no effect on the vibration. As far as comparing it to a miss, that might over state it a little. It might better to compare to a slight ballence problem, years ago a I accedently used a zero ballence flex plate on a 460 truck motor that requiered a weighted one- this feels simaler to that.

 

[Bondo]

Re: 5.7 alpha 1 vibration

Ayuh,... About the only thing that is Balancable, or can be outa balance in/ on the drive, is the Prop...

Or,...
Possibly a broken/ cracked tooth on a gear...
But if that were the case, I'd think it would have made itself Well Known by now...

 

[rthomas]

Re: 5.7 alpha 1 vibration

Roger the prop, but it does it in neutral as well, the only thing that jives for me is worn splines in the coupler causing slop and letting the shaft wobble a little, but thats a lot of work if its not it.

 

[GLENN M]

Re: 5.7 alpha 1 vibration

use an alignment bar and check in all 4 positions 12,3,6,9 oclock.wont tell you if out of balance,but will tell you if its not spinning true.

 

[rthomas]

Re: 5.7 alpha 1 vibration

Good idea- Ill borrow an alignment tool check it when i pull the drive, I know if the alignment is way off it will take out the gimbal bering but I could see if its a little off it might give me the vib.

 

[starsnstripers]

Re: 5.7 alpha 1 vibration

Check the easy things first, I have two props of the same size. I put one on and it had a vibration, i put the other on and it had a worse vibration. I have two props that "LOOK" great no nicks dings or anything bent. I spun the props and the center hub is a tweek out of wack. Dont ask me why but thats what caused a pretty good vibration. Try a different prop if available or check yours really good for a out of true hub. Good luck!

 

[bruceb58]

Re: 5.7 alpha 1 vibration

Try a different prop if available or check yours really good for a out of true hub. Good luck!

He said it does it in neutral.