4.3 Mercruiser V6 sudden vibration/noise, constant, not only when in gear

[twozeroone]

I was on the pond today and had something strange happen. It was running great, this was the first trip of the year. I slowly warmed it up, had it at idle speed and brought it up to about 30/35mph a couple times. I was driving at about 3/4 throttle and it started making a loud vibration almost exhaust leak type sound. Looked closer and I don't think it is an exhaust leak, maybe a bearing threw somewhere? It is a rattley type sound. It is constant, even when in neutral. It shifts into forward and reverse fine and I kept it at trolling speed all the way back to the ramp. Not over heating, oil pressure is fine, the outdrive itself feels tight.

Any ideas?????

 

[cr2k]

Re: 4.3 Mercruiser V6 sudden vibration/noise, constant, not only when in gear

If it's a Cobra probably the gimbal bearing or u-joints. Did you try greasing the gimbal bearing? Starboard side right near the transom there is a zerk 10-12 pumps.
If it is a stringer could be ball gears, intermediate bearing or?

 

[twozeroone]

Re: 4.3 Mercruiser V6 sudden vibration/noise, constant, not only when in gear

Hello Thanks for the advice, I tried to lube the gimbal. it is an alpha one outdrive. When the trim is almost all the way down it sounds a bit better, but when it is up at a slant it gets a lot louder, that makes me thing it is a bearing on the u joint perhaps? I took a video, you can take a look and listen here. Let me know what you think and what it would take to fix? Here is a video:

http://www.youtube.com/watch?v=hNheN40awh8&feature=youtu.be

 

[gotmud4130]

Re: 4.3 Mercruiser V6 sudden vibration/noise, constant, not only when in gear

Hello Thanks for the advice, I tried to lube the gimbal. it is an alpha one outdrive. When the trim is almost all the way down it sounds a bit better, but when it is up at a slant it gets a lot louder, that makes me thing it is a bearing on the u joint perhaps? I took a video, you can take a look and listen here. Let me know what you think and what it would take to fix? Here is a video:

http://www.youtube.com/watch?v=hNheN40awh8&feature=youtu.be

I just watched your video and I might have had the same problem..I had my boat on the water for the first time since last year waiting for new risers and manifolds...When my gimble went out it made a humming vibration not a clunk or heavy offbeat shake like a padded sledge hammer rolling over hotdogs and taping a wooden table witch is excactly what I'M getting now at Idle in or out of gear and through the lower rpm's untill the motor noise blends it out...Its hard to tell in your video but it reminds me of my gimble bearing ...

 

[cr2k]

Re: 4.3 Mercruiser V6 sudden vibration/noise, constant, not only when in gear

You should be in the Merc forum not the OMC.

But it sounds like the gimbal bearing to me. Either way you gotta pull the drive.