4.3 Chattering noise coming from rear of engine

[excessiveego]

I have a sunbird eurosport 2 with the 4.3 OMC I/O and it was perfectly fine last time it was run but I started it today and there is a chattering noise coming from the rear of the engine.

the noise is the same in forward, neutral, or reverse and is not noticeable at an idle, but as soon as it is reved up it becomes instantly noticeable and gets slightly louder for the next couple hundred RPM's and then seems to go away at higher RPM's.

this is my first I/O and only being familiar with engines in cars my first thought was possibly a cracked flywheel. My question is, is there anything else between the engine and outdrive that is moving while in neutral that could cause this noise, thanks.

 

[tpenfield]

Re: 4.3 Chattering noise coming from rear of engine

Yes, the whole business is moving. The shifting happens down in the lower part of the outdrive.

Do you have a video that you can post so we can hear and see?

 

[excessiveego]

Re: 4.3 Chattering noise coming from rear of engine

I tried to take a video but you cant hear the noise over the sound of the exhaust

 

[RogersJetboat454]

Re: 4.3 Chattering noise coming from rear of engine

Has the outdrive been pulled to inspect the gimbal bearing, bellows, and u-joints?
If not, time to pull it.

 

[excessiveego]

Re: 4.3 Chattering noise coming from rear of engine

everything was greased last season and the boat was only put in the water a couple times, but i figured that pulling the drive was the next step/simplest thing to check, thanks

 

[subcrx]

Re: 4.3 Chattering noise coming from rear of engine

Gimbal bearing. Grease it up again while it's running. See if it changes at all.

 

[Speak]

Re: 4.3 Chattering noise coming from rear of engine

I had a similar prob. Sounded like from the rear but it turned out to be the alt belt. Sound like something ready to snap. Try remove your belts for a sec and run the engine s
Just for moment to see. Not too long cause the water pump won't be running. Just additional thoughts may be off track but worth a look.

Stu

 

[excessiveego]

Re: 4.3 Chattering noise coming from rear of engine

Gimbal bearing. Grease it up again while it's running. See if it changes at all.

definitely gimbal bearing lowered the drive about half way down and greased the bearing with the engine running and the noise stopped. Now the question is, should I still pull the drive and replace the bearing? Is the noise a sign it is close to failing?

 

[dnnsmrgn]

Re: 4.3 Chattering noise coming from rear of engine

REplace gimbal bearing now, or you will tear up more stuff at high speed or out in the middle of the lake stranded

 

[Levinz11]

Re: 4.3 Chattering noise coming from rear of engine

REplace gimbal bearing now, or you will tear up more stuff at high speed or out in the middle of the lake stranded

Not necessarily.

I would pull the drive and feel the bearing first. Does it operate smoothly? If so let her ride for another season or two or three. If it has some rough spots throw a new one in.

Grease everything now that you know how important it is steering, prop shaft, throttle and shift linkages,