Flywheel movement

[ptbrakefield]

Pretty sure I know the answer to this, but I'll throw it out there...

94 120...

I've had a rattling from the engine. Worse at lower rpm and trimmed out. Don't hear it at all when trimmed out at high speed. It's been driving me bonkers. Today, on a whim, I grabbed the flywheel and shook it back and forth. It moved just enough to make a clicking sound. Should it move AT ALL? I'm talking tiny fractions of an inch, but movement none-the-less.

Paul

 

[racerone]

Put a dial indicator on it and tell us how much movement.-----Tiny fractions of an inch mean nothing at 1000 miles away.

 

[w2much]

Pretty sure I know the answer to this, but I'll throw it out there...

94 120...

I've had a rattling from the engine. Worse at lower rpm and trimmed out. Don't hear it at all when trimmed out at high speed. It's been driving me bonkers. Today, on a whim, I grabbed the flywheel and shook it back and forth. It moved just enough to make a clicking sound. Should it move AT ALL? I'm talking tiny fractions of an inch, but movement none-the-less.

Paul

Seems to me to be bearings or connecting rod wear.

 

[ptbrakefield]

Put a dial indicator on it and tell us how much movement.-----Tiny fractions of an inch mean nothing at 1000 miles away.

I don't have all of that. Sorry...

When I hold it on each side of the flywheel and push it away and back toward me quickly it moves enough that you hear a tick-tick-tick-tick sound in each direction.

But... Should it move or make any noise AT ALL while doing that? Is there a possible tiny amount of play that is ever acceptable?

 

[flyingscott]

They all move a little bit because there needs to be space for the bearings to expand. How much is the question there is a spec. Have you pulled the lower unit off and checked that?

 

[F_R]

So you are talking about fore and aft movement? Some movement is normal, but wouldn't be noticed by the average bear. It would have to be measured by a dial indicator as previously suggested. Even then, the manufacturers usually don't give a spec. If you are getting a few thousandths of an inch, you got trouble.

 

[oldboat1]

fair to say, if he can feel it it's too much?

 

[flyingscott]

Most people who end up trying to measure side to side movement on the fly wheel actually are pulling up on it.

 

[oldboat1]

^^Might retorque the flywheel, just in case.

thread has been around here as long as I have -- might be instructional: https://forums.iboats.com/threads/noise-in-flywheel-loose-bearing.138139/

 

[Sea Rider]

Which 2 or 4 stroke motor brand and HP are we talking about ? When shooking the flywheel sideways back and forth does the upper crankshaft moves along ? Need to determine if it's a flywheel issue or not, remove it and shake the upper crankshaft sideways to check if with side play too. There should be 0 side play regarding the flywheel as sits well pressed tight against the crankshaft.

If the upper portion of the crankshaft has side movement could be due to upper crankshaft's wear or upper ball bearing wear where sits housed inside the upper crankcase. If the upper ball bearing have excesive wear will hear the motor rattling at high speed. Nothing to worry at the moment, only the annoying rattlesnake sound...

Happy Boating​

 

[racerone]

Posted in the Johnson forum.----And a 1994 model 120 would be a 2 stroke !

 

[ptbrakefield]

They all move a little bit because there needs to be space for the bearings to expand. How much is the question there is a spec. Have you pulled the lower unit off and checked that?

It was checked a couple of months ago when I had a new impeller installed.

 

[ptbrakefield]

Most people who end up trying to measure side to side movement on the fly wheel actually are pulling up on it.

As I may be...

 

[Sea Rider]

I totally disagree on : They all move a little bit because there needs to be space for the bearings to expand. If that were true there would be a huge wear at both crankcases's ball bearing round mating/sitting sides. If all bolts remains well torqued to factory specs there should be 0 bearing circumferential play...

Some crankshaft's have their ball bearings pin locked onto their respective circular seats for them not to spin inside the crankcase, don't know it that's the case ?​

Happy Boating

 

[racerone]

This particular motor has roller bearings ( not a ball bearing ) at the top of the crankshaft.-----And a roller bearing for center main.------A ball bearing for the bottom bearing.----Roller bearings MUST have clearance to operate.----Therefor we need a dial indicator reading.-----Other guesses do not count !!

 

[flyingscott]

I totally disagree on : They all move a little bit because there needs to be space for the bearings to expand. If that were true there would be a huge wear at both crankcases's ball bearing round mating/sitting sides. If all bolts remains well torqued to factory specs there should be 0 bearing circumferential play...

Some crankshaft's have their ball bearings pin locked onto their respective circular seats for them not to spin inside the crankcase, don't know it that's the case ?​

Happy Boating

Ever see what happens when bearings heat up. It's called expansion.

 

[racerone]

There has to be some clearance for the oil film.----Ever heard of a ----" hydrodynamic wedge "-----When it comes to oil and lubrication ?

 

[flyingscott]

It doesn't matter the reason. There is clearence built into bearings no mystery no conspiracy reasons just IS. And you can hear the click on a 2 strk motor.

 

[ptbrakefield]

Just got back to wifi. Thanks for the thoughts and responses. I'll keep an eye and ear on things, and get it to my mechanic if I think it warrants. It just kind of startled me initially.

 

[ptbrakefield]

Which 2 or 4 stroke motor brand and HP are we talking about ? When shooking the flywheel sideways back and forth does the upper crankshaft moves along ? Need to determine if it's a flywheel issue or not, remove it and shake the upper crankshaft sideways to check if with side play too. There should be 0 side play regarding the flywheel as sits well pressed tight against the crankshaft.

If the upper portion of the crankshaft has side movement could be due to upper crankshaft's wear or upper ball bearing wear where sits housed inside the upper crankcase. If the upper ball bearing have excesive wear will hear the motor rattling at high speed. Nothing to worry at the moment, only the annoying rattlesnake sound...

Happy Boating​

It has the rattlesnake sound but in low to mid rpm. Maybe at top end it's happening too fast to hear it.