What is this sound? (@3500rpm & up?)

[nospark1196]

Alright guys, let's put our thinking caps on. I purchased an '02 50hp Tracker and boy was it hard to start and keep @ idle. So, I posted my problem and Y'all helped. Now, after the gasket kit, new fuel line, and we can not forget the Seafoam(Mercury.Grease.Rag)ha,ha.The engine runs better @ idle and thanks to other posts, I can get it to start w/out using throttle advance. Now, my new problem is a noise that I hear only after I get over 3500rpm. I know it is hard for y'all to fully understand, but I will try to describe as best I can. It almost sounds like car keys jingling under the cowling. It is a light jingle, it does not sound like metal grinding. I know this is a hard one, but I'm sure y'all can handle it.<br /><br /> many thanks,<br /> <br /> nospark

 

[DJ]

Re: What is this sound? (@3500rpm & up?)

Hard to say.<br /><br />Are the engine cowl clamps tight?<br /><br />Anything loose under the hood/cowl?

 

[The Marine Doctor]

Re: What is this sound? (@3500rpm & up?)

Does your engine have a rewind?<br /><br />Its possible that it's either vibrating or touching the flywheel.<br /><br />TMD

 

[nospark1196]

Re: What is this sound? (@3500rpm & up?)

it's electric start, so I don't think it has a rewind(if that is what you are refering to)The cowling is secure. The only other time I heard this sound , or something similar, was in a car when it was getting throttle. This sound is a "soft" jingle. I can't describe it any other way. It just happens whem I reach around 3500 rpm and above. I just don't want to screw this motor up.

 

[clanton]

Re: What is this sound? (@3500rpm & up?)

The 50 I have does this at two different rpm spots. Other posters have posted this problem. Sound like spark knock to me. I dont put many hours on this engine, so havent check it out yet. I am running 91 fuel and mixing 100-1 in tank until I feel like checking the timing at all rpms. No decrease in rpms, speed or power. when this happens, I change engine rpms until noisy stops. I talked to dealer yesterday that has sold thse engines since OMC went out, 40, 50, and 60s same block on pontoon boats. He said almost no warranty problems with this engine.

 

[bubbakat]

Re: What is this sound? (@3500rpm & up?)

Try checking to see if starter bendix to see if it is doing the jingling mine did on my merc 50 and almost drove me nuts<br />but that would have been a short trip though

 

[nospark1196]

Re: What is this sound? (@3500rpm & up?)

Thanks for all the responses. I will run higher octane. Is there anything else I can do to prevent "spark plug knocking" ? Is "spark plug knocking" damaging my cylinders/pistons ? Do I need to add more oil into the tank(My injector still works fine) ? I don't lose RPMs or MPH when this happens. I just didn't want to ignore the "jingle" if it was going to damage my "baby".