1989 Sea Ray 5.7L Alpha 1 Knock In Forward Only

retrojeep

Seaman Apprentice
Joined
Jun 23, 2006
Messages
44
Evening all,

Just got back from taking out my 24ftr and about 1/2 mile from the dock I had a nasty knocking from the drive leg. It hit almost instantly and I shut it down right away. After cleaning my shorts out I did a low rpm test in forward. Unfortunately it was just as loud no matter if the leg was up or down, left or right. The sound level didn't change. Pretty much the same sound at the same level with the only difference being that if I revved it up a bit it got more repetitive. It would knock proportional to the rpms. It was pretty loud and heavy thumping. At first (and I still do) thought it was a ujoint spent, however (and this is the strange part), when I would put it in reverse the noise went away completely. What the heck?

Obviously in reverse the ujoints aren't going in reverse (this action happens in the leg) so the load should have been the same on the drive shaft line. So could this have be a bad upper or lower unit?

I drained the oil tonight and it was fine with only a few shavings on the magnet.

When I would put it into gear (with the motor off) in forward it would hold in one direction and ratchet in the other. Reverse acted the same way. I'm not sure if this is normal, but seems correct from what I have read.

Out of the water with muffs, there is a really low thumping noise in the unit and it is consistent, but I haven't located it. It isn't anything like what I heard in the water, but I give this to not being under load. It still sounds like the u-joints so I'm kinda confused about the noise disappearing when I was in the water and going in reverse.

I'll probably pull the unit off tomorrow night to check the joints.

Any thoughts please?

Have a great night!
TF
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: 1989 Sea Ray 5.7L Alpha 1 Knock In Forward Only

Drain the gear lube and check for metal on the drain plug magnet. Sounds like you may have chipped a tooth on the forward lower gear.
 

retrojeep

Seaman Apprentice
Joined
Jun 23, 2006
Messages
44
Re: 1989 Sea Ray 5.7L Alpha 1 Knock In Forward Only

There was only a tiny amount of shavings on the magnet. About 6 or 7 flakes that were about 1/1000 thick. No chunks or large nuggets. Oil was dark, but no metal sparkles or grit to the feel.
 

retrojeep

Seaman Apprentice
Joined
Jun 23, 2006
Messages
44
Re: 1989 Sea Ray 5.7L Alpha 1 Knock In Forward Only

Evening,

Just pulled the outdrive and the u-joints are all good (a tiny bit lose, but will change anyway). U-joints are all well lubed. The gimble bearing is smooth as butter and well lubed. No water intrusion or any signs of rust on the drive shaft.

Can you run the motor without the outdrive on if you have someone hold a hose in the water inlet?

Guess the only thing left is pull it all apart and see if I have a chewed gear. I may have shut it down fast enough to keep most of the internal parts in one piece (I hope). Though at this point it maybe easier to just get a rebuilt unit.

Will dig deeeper....
 

retrojeep

Seaman Apprentice
Joined
Jun 23, 2006
Messages
44
Re: 1989 Sea Ray 5.7L Alpha 1 Knock In Forward Only

Got it torn down and the forward gear is down to only 2 teeth and reverse is missing a couple. Time for a new lower unit....
 
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