115hp Evinrude intermittent horrible noise

[bertherr]

My engine has 120 lbs compression +/- 2 lbs on each cylinder. The VRO system is disconnected. The VRO connector ends are not taped where pulled apart at the back side of the engine. The engine seems to be running rich. I say this because the exhaust water leaving the prop is very dark. The flywheel has one tooth's worth of back and forth play.<br />It gets a disturbing noise when I open the throttle under load, after about 30 seconds. It will not make the noise running on land. It sound like a loud ping or a heavy eletrical arc or baseball cards in bicycle spokes. Sure is hard to describe a noise! The first time I heard it I shut it down thinking the engine was destroyed. It actually did not turn off with the key turned off without pulling the throttle back. Any ideas? Thanks, Bert

 

[almost retired again]

Re: 115hp Evinrude intermittent horrible noise

Hello Bert;<br />I really don't know what you're discribing, but it sounds to me like the starter might be trying to engage at times and hitting a spinning flywheel. This could be a faulty key switch.<br />Lots a Luck

 

[12Footer]

Re: 115hp Evinrude intermittent horrible noise

Check the sound proofing insulation under the cover. It's not uncommon for this stuff to loose it's grip, and fall down on the flyweel.<br />Also, start the engine on the muffs at night in pure darkness.Look for arcing around the coils, spark plug wires,plugs, and CD.<br /> Also,see if you can trace the wires under the flywheel,to see if any of them comming from the stator or trigger coils is contacting the flywheel. If possable, pull the flywheel to get a better look.

 

[bertherr]

Re: 115hp Evinrude intermittent horrible noise

Thanks. I did run it with the cover off to look at the starter gear. It's not this gear making the noise. It also made the noise without the insulation nearby. I'm going to try running it at night as suggested. Bert

 

[ICEMAN]

Re: 115hp Evinrude intermittent horrible noise

Hi, What year is your motor? You mentioned that you have one tooth worth of back and forth play. Does the flywheel have up and down play?

 

[bertherr]

Re: 115hp Evinrude intermittent horrible noise

The engine is a 1985. The one tooth play is rotational. Bert

 

[Cut n' Jump]

Re: 115hp Evinrude intermittent horrible noise

Could the noise be spark knock? Like the clattering made by a vehicle with bad gas. 12footer's comment about arcing goes along with this. When you say the flywheel has rotational play does the nut and crank move with it. Does the engine lose power when it makes noise? When you check for arcing if it appears ok spray some water on it. Its best to check for arcing under a load [voltage goes up under load] but this is hard to duplicate. Those adjustable spark testers available at auto parts stores will up the voltage output into the arcing range.

 

[bertherr]

Re: 115hp Evinrude intermittent horrible noise

It does sound like spark knock, loud spark knock. It does loose power, I think. As soon as I heard it I turned the key off. That is when the engine did not quit until I throttled back also. I mentioned the flywheel rotation to eliminate worn wrist pins or connecting rod bearings. Everything turns. I checked a friends 100hp Johnson and his had two teeth of rotation (by hand with finger tip force). Please keep the thoughts coming. I appreciate them all. I do not get a chance to test again until this weekend. Bert

 

[novacane]

Re: 115hp Evinrude intermittent horrible noise

could the shift diodes be feeding pwr back <br />giving eratic spark im no boat tech just know enough to make me dangerous something kept the ign on and i think thos shift diodes<br />can short good luck

 

[Franki]

Re: 115hp Evinrude intermittent horrible noise

Just some tips I have used over the years with cars...<br /><br />You have had the cover off while the engine was making the noise?? if so, where was it coming from?<br /><br />One thing I have done many times in the past is to get a ruddy big screwdriver and put one end hard against part of the moter, and put your ear against the other end of the screwdriver.. that helps you hear inside the motor through the screwdriver.. geat for hearing big end knocks on car engines.. maybe useful to eliminate things here.<br /><br />have you decarbed your engine at all?<br /><br />don't know about 2 strokes, but in auto engines, carbon can glow red and ignite the mixture without a spark at all.. and they way you describe haing to back off the throttle to stop it sounds familiar.<br /><br />in the same vein, are you runnign the right plugs? if you have really hot plugs in, they can glow as well (in extreme cases)<br /> but that would result in a hole in your piston/s before long..<br /><br />Where the noise is actually coming from is the key here.. find that out, and it shouldn't be hard to diagnose.<br /><br /><br />rgds<br /><br />Frank

 

[Cut n' Jump]

Re: 115hp Evinrude intermittent horrible noise

Do you have a motor flusher? The spark tester and spraying water on plug wires would be things to do in your driveway. A cheaper way that I use is to ground a test lead to the motor and a pair of long rubber handled needle nose pliers or spark plug pliers. Run the pliers along the wires and see if spark jumps out of them. If not pull the wire slightly away from the plug and see if the spark jumps at the coil or somewhere else. Don't try this if you wear a pacemaker or have a heart condition! I'm a mechanic and the occasional 30,000 volt shock doesn't phase me much. If you're careful you won't get shocked.<br />Upon rereading your last post "That is when the engine did not quit until I throttled back also" were you at speed and maybe the prop kept the motor turning?

 

[Hooty]

Re: 115hp Evinrude intermittent horrible noise

bertherr,<br />Pull the plugs out of that rascal and look at them real carefully.Do you see something on them that looks like little silver specks? If you do, that noise you hear is pre-ignition and it's real bad juju. Keep us posted.<br /><br />c/6<br /><br />Hooty

 

[petryshyn]

Re: 115hp Evinrude intermittent horrible noise

The kill wires from each pack connect together and then go to the kill switch. Try disconnecting the kill wires right at the packs.(black /yellow) There is an isolation diode in the packs that separate them electricaly. If this diode fails or leaks, it can cause one pack to fire the other at unappropriate times. This could cause early timing and harsh noises caused by crank and rod play being tormented and even detonation.<br />Its a long shot, but what do you have to loose....<br />

 

[bertherr]

Re: 115hp Evinrude intermittent horrible noise

I did three things to my engine and the noise is gone and the engine cuts off with the key now. I'm not sure which item actually cured the noise. Here they are:<br /><br />1. I taped the connector for the unused VRO pump.<br />2. The connections for two of the kill wires were corroded. I cleaned them.<br />3. I found a broken clamp on one of the coolant hoses at the rear of the engine. I had found that the engine was getting wet. I put on a new hose clamp.<br /><br />Thanks for all of the ideas. Bert <br />