SOLVED!! 'New Noise' (not good)-1995 2300SC 5.0L Alpha 1

[Mad Max]

I've had many boats in the past, a few Merc I/O powered. I now have a 95 Maxum 2300 SC with 5.0L A-1 drive. I just purchased it recently, initial on-water test run was fine.

Got family out for inaugural run to local lake. Everything fine, warm up good, idled out past bouy's, drive lowered, 3-5 minutes letting everything warm up. All fluids/temp good. Eased up throttle, boat moving well. Coming up on 15-20 mph, started bringing trim up. At 20+ (did not catch tach), felt immediate vibration in drive train. It occured 'all of a sudden'. Pulled back throttles, still vibration (very fast and consistent frequency). Shut down. Checked prop for potential damage from log or something. That was good. Started engine again, still noise and vibration (not thump or knock type). Drive engages ok.

Cancelled outing, idled back to dock (still vibrating, critical fluids/temps still normal).

I plan to take it back to shop tomorrow. Any ideas on what could be the culprit? Don't have much history on boat. It is very clean and appears to have had good maintenance (it usually shows).

I've never had a malfunction like this. Crunched a lower unit on a submerged piling once. I know that feeling and sound. Not like this one. Does a failed impellar or pump contribute this type of problems? I here about them failing but can only assume an increase in temps as an indicator.

I know this is lengthy but having all the information........ may help with a more direct diagnosis.

Thanks in advance,
(no buyers remorse at all, really)

[seapuppy]

sounds to me like one of 2 things.....either the coupler or u-joint...or you spun the prop....it's not going to show any damage until you pull the prop and bang the hub out....that's what I'm thinking from your description.....
the impeller is going to manifest itself as higher temps.....you won't feel a vibration from the impeller....
hope this helps...

[Mad Max]

Thanks. I'm thinking the same with the u-joint or coupler. When it happened, I was under load and it sounded like something 'slipped' allowing the rpm's to surge and the boat lost momentum. Prop looked good. I did remove it to inspect.

Its at the shop now, should have response soon. I will post the outcome.

[Mad Max]

Seems the past owner did not have it in the water for the past 3 years and the upper shifting shaft seal leaked, allowing water into the bellows. Caused the gimble bearing to sieze to the shaft.

At shop getting new shaft, bearing, and since were in there, u-joints.

On the water soon.

[seapuppy]

good news....hope your out on the water really soon.....!!! :D

[Mad Max]

After our initial 'float' of about 1/8 mile, our 'new' boat is fully seaworthy again.

We had the yoke shaft, gimble bearing, u-joints, and shift shaft bushings replaced. Took her out yesterday for an awesome 4 hour cruise. Runs great!

Looking forward to many 'adventurous' hours this summer.

[seapuppy]

now thats great news...have a good summer...maybe post some pic's too!!....

[Mad Max]

Posted pics at www.madmax.smugmug.com (http://www.madmax.smugmug.com)

Enjoy

[Flying_Maxum]

You have great taste, that is the exact same color combo as my 2100 SR2! Enjoy your boat.

[Mad Max]

Just a quick progress note to close out this post.

We have had 3 good trips following the replacement of the upper outdrive parts (yoke shaft, gimble bearing, u-joints, seals, and of course, the culprit, the lower shift rod seal).

Thanks everyone for the tips and advice. Enjoy the summer. I plan to have a very comprehensive winterization done so next year, no problems.