Alpha 1 stern drive thump

[bkearse]

I just reinstalled my 89 Alpha 1 stern drive after an exhaust bellow install and shift lever replacement. The stern drive shifts easily and will go into reverse,neutral, and drive. In drive and reverse I can hear a slight thumping noise coming from the stern drive area. No noise in neutral. I don't remember hearing this noise before the bellows repair.

 

[KRS]

Re: Alpha 1 stern drive thump

Was this your first time reassembling the drive?Is the drive leg fully down?

 

[bkearse]

Re: Alpha 1 stern drive thump

Yes this was my first time and the drive was all the way down. Maybe I did something wrong during installation?

 

[flashback]

Re: Alpha 1 stern drive thump

I would check the u-joints first and probably change them out just to be safe...If you turn the drive and the sound gets louder It is probably the u-joints...

 

[bkearse]

Re: Alpha 1 stern drive thump

I did lubricate the u-joints but didn't check them for play. Do the u-joints turn when the boat is running in neutral?

 

[flashback]

Re: Alpha 1 stern drive thump

Yep, they turn whenever the engine is running, only in neutral, they don't have any signifigant load on them. Also when the drive is down and centered they have less load on them than when the drive is turned to full port or starboard..Thats why they ususally rattle more when the drive is turned...

 

[bkearse]

Re: Alpha 1 stern drive thump

Thanks for the advice. I will let you know when I pull the drive again. Looks like the rain is going to stall me this weekend.

 

[bkearse]

Re: Alpha 1 stern drive thump

I pulled the stern drive today and u-joints look ok. I'm puzzled at this point. Is it possible the u-joint were not fully extended or the shaft wasn't all the way in the spline?

 

[DHPMARINE]

Re: Alpha 1 stern drive thump

Not if you had the drive bolted on all the way.Do you have a stainless prop ? Sometimes they can sound funny running on a hose.<br /><br />DHP

 

[bkearse]

Re: Alpha 1 stern drive thump

No stainless steel prop, and I did bolt everything tight. I've read a lot of posts about engine alignment. Would the alignment tool still be needed even if the motor was not moved?

 

[flashback]

Re: Alpha 1 stern drive thump

batley, did you take one of the joints apart and look at the spyder journals? just because they "look" ok from the outside doesn't mean much..

 

[Boatwizard]

Re: Alpha 1 stern drive thump

Is this running?<br />In or out of the water?

 

[bkearse]

Re: Alpha 1 stern drive thump

Flashback, I didn't take the u-joints apart yet. I checked the oil, no metal flakes and removed top cover, no broken gears. I was running the boat out of the water with earmuffs. Recently I turned the shaft by hand and couldn't feel anything jumping or slipping. I will probably put everthing back together and see what it sounds like in the water. Thanks

 

[bkearse]

Re: Alpha 1 stern drive thump

Thanks for all of your help. I reinstalled the stern drive again with new oil and it sounds great. The first time I intalled it without help and maybe the splined shaft did't seat properly (I don't know). I'll keep my fingers crossed when I hit the Bay.