97 200 HP Ocean Runner vibration (lower unit suspected)

I have a 1997 200 HP Ocean Runner that is exhibiting a vibration problem that only occurs in forward gear up to about 2000-2200 RPM. It is obnoxious enough to actually make items near the transom rattle. The vibration goes away when the engine is running at speed, or at least it is not noticable.

I have drained the gear oil and there was no water and the only metal I could find was the usual powdery filaments on the plug magnets. No shavings just powder that feels like grease between the fingers. I bought clamp on dial indicator and check to see if the shaft was bent. There is a noticeable slop in the fore and aft direction which I understand at least to some extent should be normal as the shaft moves from contacting the fore and aft thrust bearings. there is also a small amount of axial play when grabbing the propeller and moving side to side. One final item is that the ****ing into foreward gear clunks much more so thatn my previous motor a 99 150 Ocean Pro which I think used the same lower unit.

I've got plenty of experience with engine work But I have never had a lower unit with problems. I'm trying to figure this out. The only thing that seems to make sense would be the ahead thrust bearing or possibly the ahead gear. Does anyone have any insight into this? I'm guessing that I am eventually looking at a lower unit teardown and inspection in my future.

Pinion could be cracked..pull the carrier and inspect

Is the prop nut tight?
Try another prop.
Does a little trim up help?
Is it running on all six cylinders equally?

Thanks for the reply Faztbullet. I figured I would be heading in that direction (disassembly/inspection). I was thinking bearings but but with the hard shift a gear issue sounds like a logical conclusion. I will post back once I open up and inspect.

Rwbutler said:

Is the prop nut tight?
Try another prop.
Does a little trim up help?
Is it running on all six cylinders equally?

Click to expand...

• It is a brand new prop and hub (4 blade) It was more noticable with the previous 3 blade. I also checked the driveshaft with a dial indicator, it was within specs and not bent.
• Prop nut tightened with a torque wrench to 55 ft lbs
• Trim does not help but RPM changes do. It is worst at idle speed disappears over 2000 RPM and not noticable at all at cruising speed through to WOT.
• The engine itself is running awesome. New to me in June. I have been completely through carbs and fuel system, new Stator, Powerpack, Regulator. Plugs, Filters new fuel lines from tank to engine. decarbbed, Lynk & Synch, Timing, cable adjustment, water pump, thermostats, drive shaft, and shift shaft seals. renewed electrical connections, lugs, new battery cables, and probably a few things I forgot to list.

Vibration seems to be isolated to happening in forward gear. I've not really noticed it in reverse. It has me stumped because I've owned several other OMC outboards and never had anything like this. Of course truth be told I've never done anything more to lower units than change water pumps and drive shaft seals. I guess I've been lucky in that regard.