115 Evinrude noise over 3800 rpms

[Shifflett115]

Hi everybody , i have a 1974 115 evinrude , i reacently got it in december of last year it sat for about 5 years befor i got it . i got it running new plugs , new coils carbs redone and impeller it , receantly it has a noise like a whirling noise , almost like a grinding noise over 3800 rpms , wot is at 5400 rpms it has never loss power or speed and at lower rpms it sounds great ,idles great ,and great throttle response . the only thing i can think of is it wouldnt charge so i put a rectifire on it, it charges but not real high , around 12.7 volts , could the rectifire be coming apart ? please help

 

[ezeke]

Re: 115 Evinrude noise over 3800 rpms

Torque your flywheel to 100-105 ft. lbs.

Cover latches will do that if they are not tight - uses the cover like an amplifier.

If your prop is not balanced, it can send vibration thriough the whole motor, not to mention damaging the oil seal on the propeller shaft.

 

[F_R]

Re: 115 Evinrude noise over 3800 rpms

Maybe it is just because I have this in mind concerning someone else's question, but a whirling, grinding noise is how I might describe a bad ball or roller bearing. That is a sound that any outboard mechanic worth his pay is familiar with. Have one put an ear to it.

 

[Shifflett115]

Re: 115 Evinrude noise over 3800 rpms

its a weird noise , its only there at 3800 rpms and above but at idle and up to 3800 rpms it sounds fine . i didnt know if the stator is coming apart or not. so it could be a bearing .

 

[hoeser]

Re: 115 Evinrude noise over 3800 rpms

You will want to find out what is causing this right quick and in a hurry, If the flywheel is loose and causing this sound I would be surprised... If this was the case you would have likely spun it and sheared the key, throwing your timing off and having it run horribly or not at all, backfiring and such.

Sometimes an impeller on its way out can make a rubber whirring sound, keep an eye on that. Otherwise I would say prop or bearing myself, hopefully not a crank bearing... just find out where it is and don't run it like that for very long.

 

[R.Johnson]

Re: 115 Evinrude noise over 3800 rpms

Take a look at the gearcase lube

 

[Shifflett115]

Re: 115 Evinrude noise over 3800 rpms

if it was a crank bearing , would i here it all the time? it has a michigan prop with the break away hub system . ive also have replaced the top and thrust bearing ,shim ,and thrush bearing washer in the lower unit, the noise sounds like its coming from the case but i hear nothing at idle and lower rpms . there is about a half a tooth of rotational play in the flywheel and no up and down play , the flywheel is tight . it has a new impeller in it [ a month old]

 

[hoeser]

Re: 115 Evinrude noise over 3800 rpms

If your flywheel is moving a half tooth before moving the crankshaft you have an issue there. It should have absolutely ZERO play as it is a taper fit and when torqued appropriately should move in unison with the crank.

 

[Shifflett115]

Re: 115 Evinrude noise over 3800 rpms

im sorry , the crank has a half a tooth of play ,the flywheel is tight to the crank and the lower unit oil is new , no medal found in old oil

 

[tschamp20]

Re: 115 Evinrude noise over 3800 rpms

you know ,it probably wouldnt hurt to take off the flywheel and have a look!

 

[tschamp20]

Re: 115 Evinrude noise over 3800 rpms

could the drive shaft have been tweaked causing it get out of balance? maybe when it was off getting new impeller.probably not

 

[Shifflett115]

Re: 115 Evinrude noise over 3800 rpms

thanks everyone for all your help , im going to pull the flywheel off tomorrow and have a look . i doubt the drive shaft was tweaked when pulled out i was very carefull with it , im hoping its somthing stupid , some one said it could be the upper crank bearing , could that be it?

 

[Shifflett115]

Re: 115 Evinrude noise over 3800 rpms

whats all envolved with decarbing a outboard

 

[ezeke]

Re: 115 Evinrude noise over 3800 rpms

Here is a link for the de-carbon information. The method by Capt. Dunkelberger is widely used:

http://forums.iboats.com/showthread.php?t=158076

 

[Fl_Richard]

Re: 115 Evinrude noise over 3800 rpms

I had a similar problem. Turned out to be a broken reed. It broke lengthwise and the reed chunk would bounce around inside the reed block at a certain RPM. Eventually it went away. The motor ingested it.

 

[hoeser]

Re: 115 Evinrude noise over 3800 rpms

:O

Wow.. those reeds (stock) are stainless steel are they not? How did your engine fair after ingesting it?

 

[Fl_Richard]

Re: 115 Evinrude noise over 3800 rpms

Yes they are stainless. The chunk that broke was about 3/4" long and shaped like a boat. Like I said it bounced around on the reed block on the intake side until it ligned itself up enough to go through the reed block. There are lots of poke marks inside the reed block and on the back of the intake manifold where it was "dancing".

The good news is the engine is just fine (after replacing all the reeds and one reed block). I still have compression equal to the other 5, I looked into the cylinder with an orthoscopic probe and there were no scratches or grooves. I think i got lucky and it sailed right through... hopefully in one stroke.

I love my Johnsons!