175 Johnson Knocking noise,,need HELP..

HS20

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Joined
Jun 4, 2005
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5
Hey Guys I'm new here and could use some help.My 1995 175 Ocean runner[<500 hrs.]ALWAYS maintained to the Max.Decarbon evey 50 hrs.,Use Ring-Free every tank or so etc.I am an Auto Tech and am very familar with Engines,BUT not a lot of experience with 2-strokes.<br /><br />Now that I have laid a little background,Heres what I have.<br /> She has been running great,but at the end of last year I thought I heard a very small knocking noise,this year I took Her out in March,surely was a knocking in the Engine.Did not go out again until Memorial Day weekend and no dought seemed to be getting louder.<br /><br /> I Fished for 3 days,knocking away!WHEN you come off idle,maybe to about 1.5-2 K rpms you can hear it.Rev it up in neutral,you can hear it [knocking]when you go up in rpm and when it comes down also.<br /><br /> I pulled the Flywheel[bolts tight]Pulled the Throttle Plates and Reeds.From what I can see the Cylinders and Pistons look damn near new.Still have cross hatch pattern on the walls,Piston skirts have virtually no scuff marks,nothing dry.<br /><br /> What I DID find and I don't know if it should be this way or not.Is I grabbed the top of the Crankshaft and yanked it back and forth[now,now Guys]and can feel the Crank move a hair,BUT when I do this,I can ALSO hear a Knock!!I would not think it should move,but like I said I am not real familar with 2-strokes.I will be after this for sure.Any help would be appreciated!!!THANKS![Mike] :(
 

Joe Reeves

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Joined
Feb 24, 2002
Messages
13,262
Re: 175 Johnson Knocking noise,,need HELP..

Mike.... You being an auto tech, I'm sure you know how to check for piston and connecting rod play so I won't go into that.... but if you haven't checked into that, I'd suggest you do.<br /><br />Also, I have encountered a few engines whereas the bottom main bearing failed which would allow the bottom portion of the crankshaft flex somewhat which resulted in quite a knocking noise.<br /><br />With the engine running and the knocking noise sounding, it would be a good idea to use a mechanic's stethoscope to locate the general area of that knocking.
 

HS20

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Joined
Jun 4, 2005
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Re: 175 Johnson Knocking noise,,need HELP..

Joe,I was thinkin' Wrist Pin myself.Can't get any movement out off them or can't feel any while I turn the the Crank back and forth.I know this is not a good way to check,but was going thru some things before I pulled the Powerhead.<br /><br /> Joe ,I did take a Stethascope on it and it seems loudest at the top portion of the Engine.Like I said in my original post:I can take the top of the Crank and yank it back and forth,can feel a Slight bit of movement in the top main bearing.BUT>>>>>When I do this I get a knocking noise,sound quite like the noise while the Engine is running.SHOULD there be ANY play in the Top Main Bearing?Thanks for your info!![Mike]
 

HS20

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Jun 4, 2005
Messages
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Re: 175 Johnson Knocking noise,,need HELP..

Got the Powerhead almost ready to come off,Think I am going to go all the way thru it.Freshin' Her up.[Mike]
 

HS20

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Joined
Jun 4, 2005
Messages
5
Re: 175 Johnson Knocking noise,,need HELP..

Got the Powerhead almost ready to come off,Think I am going to go all the way thru it.Freshin' Her up.[Mike]
 
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