Motor noise?

[DEISWERTH]

Was out in my boat today and when I went to move the motor started to make a kind of knocking  noise and sounded like it was missing on maybe one cylinder? It would idle, but start to make the noise if you gave it gas. Shut it off and used the trolling motor to get back. Took it right to the marine shop. Said it may be a bearing or a rod? Don't know anything about this stuff, but I think it is going to be expensive. Anybody have any ideas.

Doug

[Jig Man]

The last time I had anything like that it was a busted piston ring on a 4 clyinder rude.  It cost me a grand to get that hole fixed.

[cart7t]

Any engine I've owned from auto, outboard, lawnmower, weed whip, etc, etc. that made loud knocking noises was rarely ever cheap to fix.  

[Sam]

Listen to your motor.

You will know when there is something wrong.

My friend's motor was making a terrible "clanking" sound and he refused to have it serviced.

Sure enough, it blew up on him.

So either get the motor repaired or buy a new one.

The Bait Monkey awaits you, either way.  ;D   ;D   ;D

[Way2slow]

Kind of motor would help, different makes have different inherient problems.

A ring locator pin could have come out.  A compression check will tell you that.

Something could have come loose and got sucked in on top of the piston.  Pulling the head off or using a flex light and looking through the plug hole should show damage on the domes is it's that.

A way to check if it's a possible rod or wrist pin is to take all the plugs out and one at a time, stick a long screwdriver through the plug hole until you feel the piston.  Then slow turn the flywheel by hand until the piston comes all the top, don't hold any pressure on the screwdriver.  Once at the top, turn it another couple of inches so the piston will be on it's down stroke.  Once you have the piston on the down stroke, give little push on the screwdriver.  There should be absolutely no free movement of the piston.  If a rod or wristpin is bad enough to be knocking, usually you will feel a slight movement or clunk when you push.

However, other than knowing what's causing it, normally if it's internal, it has to come apart.  If that happens, plan on a bad christmas.

[DEISWERTH]

It's a Yamaha 50 horse jet. Thanks for the info! I don't expect it to be cheap Like I said, I took it right to the marine shop from the river. They said they would not get to it till December because they are winterizing a lot of boats right now, which is a little better because that is when there winter rates start. It never sounded any different before this??

Doug

[thetr20one]

I get queasy thinking about engine noise. The last time my motor made a funny noise I was 3 miles out on Erie. With three broken rods three shattered pistons and fist sized holes in the block from the rods coming through. Dead in the water. I was only at 45 mph and about 3500 rpm. Luckily my brother in law was right behind me in his boat and it was still under warranty. Merc had some problems with the earlier Opti's. I hope you fair better. Boating is expensive.