Printable View
So I’ve started hearing a rattle or knocking sound coming from the motor area. I can hear it at an idle but not when I throttle up. And I think I can hear at when I’m at highest rpms but not at mid throttle. And it almost sounds like maybe fly wheel area but not sure. Any ideas would help
Sent from my iPhone using Tapatalk
What size and make of motor ? and check your prop as some have a lot of play on the shaft that can rattle or vibrate when in what I call float mode. My new to me 2012 60hp 4stroke merc did this and I found plastic hub was compressed in and after taking apart lubing shaft and reinstalling the noise went away.
2002 Mercury 50hp 2 stroke. It just got overhauled last year. I checked spark plugs and no metal shavings on plugs. I’m goin to upload short video of it running soon. Well said I was but it won’t let meQuote:
Originally Posted by downtime
Sent from my iPhone using Tapatalk
I would start by checking flywheel mounting bolt, then go around motor checking all mounting bolts like starter and any othe accessory mounted to block. Also I would check compression. Almost sounds like piston slap starting to develope.
When it’s at an idle it almost sounds like it’s around the flu wheel areaQuote:
Originally Posted by Cray
Sent from my iPhone using Tapatalk
Does it do it in neutral and fwd/rev?
Yes u can hear it when rpms are at or near idle or in neutral. When u get quarter to halfway throttle it goes awayQuote:
Originally Posted by sliderman
Sent from my iPhone using Tapatalk
I would not run the motor anymore and take it back to whoever did the rebuild for inspection. There are too many potential causes that just can't be diagnosed over the net. It could range from not so bad to expensive.
Kind of figured that myself. I noticed it a few weeks ago and it wasn’t that noticeable and I took the cover off and could hear it better so It started bothering meQuote:
Originally Posted by sliderman
Sent from my iPhone using Tapatalk
Pull the flywheel and make sure a magnet isn't coming loose.
I’m gunna try checking the fly wheel if that ain’t it I’ll let a mechanic look at it tell me what he thinks and go from thereQuote:
Originally Posted by wilbur
Sent from my iPhone using Tapatalk
So i cranked it back up today to really tryin and listen to rattle and I have centralized it to just below the motor. Sounds comes from where my light is shinning
Sent from my iPhone using TapatalkAttachment 288455
Unless Sliderman knows something about that merc I don't my first inclination would be to check the bolts that hold power head and center section together. The only thing in that area that can rattle I know of would be the exhaust tuner. On merc I don't know if it is held in place by pressure from power head or if it has its own hold down bolts. Since you said it was rebuilt I'm just thinking something might not have gotten installed properly. Also did you ever check the prop hub for looseness.
Cray, the tuner does bolt up on that motor. The issue I'm seeing is that there are too many possibilities to accurately guide the owner in making a repair. Of the many things I've seen on those motors, the magnets are trouble free and if one were to come loose, it would wipe out the stator. Not rattle. The rattle could be in no certain order; loose flywheel nut, failing top crank bearing, rod bearing, piston slap, detonation, loose tuner or powerhead attachment bolt, or something coming loose in the lower unit and resonating up the driveshaft. And there's probably some more things that aren't coming to mind at the moment. Those motors suffer from an issue were small gravel or vegetation collect behind the thermostat which leads to an overheat problem. Based on what I know, his best option is to contact the rebuilder or a competent tech and have it checked out.
Well I plan on check for rod knock this evening if I got time. And I pulled in and Out on prop and had bout 1/8-1/4 inch of play to it didn’t seem like much . And I figured if it was lower it could still send vibrations up the shaft to make it sound like motor. I’m not scared to break the motor down and change bearings I’m just not real good at diagnosing this issue. My first thought was a bearing possibly but like u said There are so many different things it could be.Quote:
Originally Posted by sliderman
Sent from my iPhone using Tapatalk
So got home and pulled all plugs check each cylinder and the number 2 cylinder I could push in about 1/16-1/8 of an inch when I ran it to all the at top of stroke and just passed it and could push it in a little and heard it. Other two where tight. So I’m gunna say rod bearing?
Sent from my iPhone using Tapatalk
I would say so. Hopefully it hasn't gotten the crank.Quote:
Originally Posted by Dewdrop
The #2 cylinder is the one that he had to bore. Kind of aggravating since he was just in it not longer than 8 months ago. If it’s a rod bearing would it stop vibrating a little higher rpm than idle?Quote:
Originally Posted by Cray
Sent from my iPhone using Tapatalk
It could at certain rpm. Since you have to pull down anyway I would check piston skirt for chaffing also or a crack around wrist pin area. You also really need to mic the cylinder for size and true and mic piston top and bottom. Hopefully he didn’t over boar cylinder.Quote:
Originally Posted by Dewdrop
He sends it off to get bored. But if the rod bearing is goin out. Would the crank me junk now? I got the right tools to do the job just not all the time in the world to pull it and break it openQuote:
Originally Posted by Cray
Sent from my iPhone using Tapatalk
It could or could not just depends. Only way to find out is pull it down and check. Visual and Mic. Just because he sent it out does not mean it is perfect.Quote:
Originally Posted by Dewdrop
Yea I’m have pull power head when I get a chance and break her open and look at itQuote:
Originally Posted by Cray
Sent from my iPhone using Tapatalk
Dewdrop,
Just out of curiosity, what was the original reason that you had the rebuild done? Was there a problem? Something similar?
The reason I ask is, you might have a similar outcome as the last time meaning that the original issue is still there even though parts have been changed.
Just a thought.
I would fully inspect both cyliders with MIC and also the crank. If the cylinder does have an issue, I'm not sure if you can overbore and sleeve those or not? Dealing with other motors, there were times when the option of a new cylinder was much better than putting a sleeve in it. As I have zero experience rebuilding outboard motors, I cannot say with any certainty. Just trying to give some ideas.
They bored #2 cylinder because it had no compression. My ? Would be if I break it open should I would guess I need replace all bearings and check pistons and cylinders?Quote:
Originally Posted by wicklundrh
Sent from my iPhone using Tapatalk