Mercury 4hp stroke whirring noise

[timsb]

I have a 2006 mercury 4hp that has been running fine when all of a sudden it started making a loud whirring noise at idle, or under power. It seems to be coming from the top of the engine but it's hard to be sure. any idea what this could be?

 

[quicktach]

Re: Mercury 4hp stroke whirring noise

Serial Number ?

 

[timsb]

Re: Mercury 4hp stroke whirring noise

The Serial Number is OR124060

 

[quicktach]

Re: Mercury 4hp stroke whirring noise

Thanks. The serial number and other data puts it as a four stroke. Some careful listening and trying to pin point is needed - tricky. But first, check the oil level and state of oil. I'd do an oil change too, checking for the presence of metal filings in the oil visually and with a small mechanics magnet. Replace oil with the best you can afford. I'd also take a look at the recoil starter to see it it's not hanging up or something's rubbing ..unlikely, but you never know. Could be noise coming from under flywheel too. Go to "**********" and search for your schematic to get familiar with your motor.
If you have a mechanics stethoscope it can be useful to try and pin point noises ...or use a long screwdriver and listen at the handle end, touching the tip around the engine...watch out for moving parts always. Check lower unit oil in case noise is coming up from below. Keep us posted.

 

[timsb]

Re: Mercury 4hp stroke whirring noise

Thanks, the oil is fresh and is clean. I'll drain it and look for metal shavings hopefully I will not find any. I'm thinking it has something to do with the recoil starter or flywheel. I am pretty good mechanically but have no experience with o/b motors. I just know once I start taking it apart that the starter coil has to be spring loaded - I just have visions of everything flying cross the garage floor once I remove it. I never seem to have much luck with those spring loaded mechanisms. I'll disect it and see what I find.

 

[timsb]

Re: Mercury 4hp stroke whirring noise

Fixed it. I removed the three bolts that hold down the starter assembly. When I lifted it off I found that nut that holds the metal cup containing the starter pawls had become undone. The cup was resting on the flywheel and that's what was making the noise. I reinserted the pawls, put the screw back in and reassembled it good as new. Did a test run in a bucket of water and everyhting seems fine. I'll buy some lock-tite and redo it over the winter. It's amazing that I was able to start the motor (twice)- I guess the starter pawls were still able to engage the flywheel.

 

[quicktach]

Re: Mercury 4hp stroke whirring noise

Good Stuff !!