wistle then grind noise at 2K RPM Yam 115

[Eric]

I noticed today intermittent wistle then grinding noise from around 2K RPM and up. Running at full throttle it seems to go away or at least drowned out by the exhaust noise. I don't want to do damage to the head but have no idea what it could be. Still runs great just sounds weird.

I pulled of the cover and one side of the block felt hotter then the other - not sure if this matters.

Any suggestions?

[Ken]

Eric,
I would first check the starter - look at the pinion gear - make sure the return spring is not broke and is doing it's job - rotate the pinion gear by hand, clockwise, I believe, and it should travel up the starter shaft and engage the flywheel. Release, and observe that the pinion rotates back down the shaft aided by the tension of the spring. What you are looking for is a possible broke spring that is allowing the pinion gear to partially engage the flywheel after the motor has been started and give a squeal/grinding noise.
Also, I believe that the long shaft outboards have a bushing in the upper casing that the drive shaft goes thru. That bushing could be going out and giving you the noise. You would have to drop the lower unit to inspect.
Or, I guess it could be a crankshaft bearing going out on you - hopefully not .
If one cylinder/head assy feels hotter to you than the other, pull and test the thermostats - one in each head.
Good luck [img]smile.gif[/img] ,
Ken K

[Eric]

Ken,
Thanks,starter looks fine. I pulled the plugs and nothing looked odd. Turned the flywheel and nothing seemed to stick except friction from the water pump. when starting again, I could not hear the noise over the exhaust until ~2K RPM again. Also, the right side (facing the back of the motor) head assembly is clearly hotter. A friend said the noise I am hearing could actually be "steam buildup" from a stuck thermostat?
Is there an easy way to pull and test the thermostats?

[Ken]

Eric,
I really think you have two issues.
One, the starboard side of your motor is noticeably hotter, and, two, you are hearing a squeal/grinding noise.
I don't think the two issues are related. If the starboard side of your motor was getting hot enough to cause steam, then the thermo switch (there are two - one for each head) would be closing (at 180 degrees f.) to indicate an overheat condition - the alarm would sound and your motor would go into rpm reduction mode (miss and shake like big time).
You can easily remove the thermostats - they are locate at the top of the heads under a cover that is held by four bolts. There is a gasket under the cover and it will probably tear when you remove the cover, so you need to get two replacements.
The thermostats can be tested in a pan of heated water, using an accurate thermometer. The stats should start to open around 130 degrees, and be fully open (.120 inches) at 140, give or take five degrees.
The thermostats could just be clogged up with mineral deposits and not opening fully. Clean if so.
If it has been at least four years since last water pump overhaul, I would do it. The noise you are hearing could be the pump. Check that bushing I mentioned earlier if you have the long shaft motor.
You need a Yamaha shop manual to guide you along on all of this. Go to www.yamahapubs.com to order online.
Good luck [img]smile.gif[/img] ,
Ken K

[jb123]

you can remove the lower unit, run with a hose hooked to your water tube to eliminate your gearcase from the "sound". if the stats are over 3 yrs old I would replace them anyway, preventative maintenance.

[Eric]

Thanks everyone for the tips - I just ordered a Yama Service book -
1) I replaced the thermostats (right side was clogged) motor sounded ok at first then the whistle noise came back followed by the metal rubbing noise. Not sure if it's realted but it seemed to happen after the motor was nice and warm.
2) changed lower unit fluid - looked fine. I guess, I'll drop the Lower unit to see if that's it. Any tricks to hook a house to the water tube?
3) Also, any good tricks to check if the overheat sensor/buzzers are working?

Again - I really appreciate the help!!

[Ken]

Eric,
You can check the alarm buzzer by shorting together the two wires that go to either thermo switch. The thermo switches are mounted in each of the two heads. About four inches away from the thermo switch, you will find "bullet" connectors - disconnect and short the two wires together (I believe they are pink and black). Do this with the ignition on - motor not running. You should get an immediate alarm. If not, then the alarm buzzer/wirinng is bad.
You can remove the thermo switches and test them in a similiar fashion that you do the the thermostats - in a pan of heated water and a multi-meter. You are looking for contact closure at approx 180 degrees f. (monitor the two leads for open/close condition - zero ohms). The switch will re-open at around 160 if it is working correctly.
Again, all of this is in the Yamaha shop manual.
Good luck [img]smile.gif[/img] ,
Ken K

[jb123]

Is the noise apparent when youre under load, out running or on the garden hose..as you will hear many unfamiliar/questionable noises that you wont hear under load,on the water.
I remember one time back a dozen yrs ago, a mechanic said he heard my top main crank bearing going out, so i had him rebuild the head....probably threw my $$$ out the window....


when the lower unit is off,the water tube is exposed on the underside and about a half inch in copper. I used a clear silicone tubing "sleeve" over the tube and my garden hose fit over both just fine. just be careful that your motor has water flow the whole time its runnin. i only did that when my gearcase was out for repair and wanted to run it/do the carbs.This was on a 150 pro-v, im not sure of your 115 water tube size,shouldnt be much different.

[Eric]

Overheat buzzer and sensors are good (in a pan of boiling water 0 ohms). Heads running nice and cool. At least this let's me feel a bit more confident I didn't overheat something.

Still hear the wistle at low rpm then sounds like something rubbing. Closest I can get to the noise is it's loudest right under the front cowling near the steering rod. Sounds almost like a venturi at low rpm. Every hear of a whistle on a 2 stroke yamaha?

Still have to drop the Lower unit but enough for the day.

[Ken]

Eric,
You're making progress [img]smile.gif[/img] .
What's the model number of that 115?
Ken K

[Eric]

Ken,
it's a 2001 115TLRZ
I am sure open to suggestions...
Thx,
Eric

[Ken]

Eric,
My C115TLRY is one year older - I don't have the drive shaft bushing I was describing earlier, and I don't believe you do either. But be sure and check anyway when you drop the lower unit.
Hopefully, it's gonna just be a water pump issue.
Good luck [img]smile.gif[/img] ,
Ken K

[Eric]

Ken,
After further investigation, it seems like maybe a whine in the exhaust - is this possible? Does anything open besides the thermostats when the motor gets hot. Once the motor get's warm, the whistle/whine starts (at idle) then goes away at higher RPM's.
I'm at least finding out what it is "not".

[Ken]

Eric,
I don't know of anything besides the stats that "open up" as the temp of the motor rises.
A "whistle/whine" noise coming from the lower cowling around the steering rod - sounds like maybe air getting sucked into the carbs around a cracked/loose gasket ?
Maybe check the air silencer - could be loose. Or take the silencer off and run the motor on the drive with the muffs and see if you still hear the noise at idle. Look into the throats of the carbs at idle and make sure the choke butterfly valves are completely open (horizontal).
Really, at this point, you are just trying to eliminate possibilities.
Did you drop the lower unit and inspect the water pump impeller?
Ken K

[Eric]

Ken,
Latest.... It appeared the noise is/was coming from where the drive shaft went into the crank. I sprayed some penetrating lub and the noise seems to have gone away for now. So, the question now is if I should not worry about it or take everything apart to inspect it. (not sure if this would mean taking off the head) I bought the manual but still not clear if this could be a bad bearing on the lower crank or just some bushing that may have had some corrosion on it. Anyone ever hear of this one? Thanks.