Rough Sounding Engine After Spark Plug Change?

[vandamit]

Quick background, I changed the spark plugs this weekend on my 60hp Mercury 4 stroke. This is something I've never done. I got the champion plugs from Orilleys. I had never gaped plugs before so they did it in the store for me. This was a fairly easy change, it took me less than 15 minutes to change them all. When I went to the lake last night for the first time I notice when the boat is in neutral it has a different sound to it that it usually does now? When i drop it in gear it sounds fine though and seems to run more responsive and and overall I thought it ran fantastic but when you put it back in neutral it sounds weird to me. I attached a video we shot. Any ideas what I might of done wrong if anything? I did pull the spark plug wires off with some pliers but i don't think that would have caused any issue for noise? It's kind of that click click click sound you hear.

[bshort]

Looks like it's running pretty smooth to me. It's not shaking like it has a misfire.

[vandamit]

It's for sure running smooth and better it just has a much different noise in Neutral than it ever has before. The old plugs were close to 10 years old.

Looks like it's running pretty smooth to me. It's not shaking like it has a misfire.

[Marky1]

Are 4 strokes suppose to be a lot quieter ? Sounds like a 2 stroke in neutral .

[vandamit]

Are 4 strokes suppose to be a lot quieter ? Sounds like a 2 stroke in neutral .

they are usually alot quieter

[gatorglenn]

I always index the spark plugs. It could be that simple. You want to torque the spark plugs to the motor Specs. But in doing so if it takes another eighth of a turn or quarter of a turn to get the open gap in the spark plug facing your intake valve. It could make all the difference in the world and how hot the cylinder is upon ignition one spark plug be turned around with the arm on the plug is facing the intake therefore it’s covering some of the spark. So even though it’s firing it may not be faring as hot as the next Cylinder in sequence with it. Yes a sharpie draw a line on the open side of the plug all the way up to the end so that when you’re installing it you can see which side is open on the plug.

[vandamit]

I put the old plugs back in and took it back out last night and it's still doing it, so it's not the plugs. I'm guessing it might be prop chatter which was suggested to me on another thread. I had some lower unit stuff done (seals, oil, water pump etc) earlier this year and I hear it's common to get prop chatter after doing that. I have the reflex hub in my prop, is it possible for them to wear out?

[billnorman1]

I had prop clank on my 4 stroke. Nothing wrong with it, just noisy.

[vandamit]

I had prop clank on my 4 stroke. Nothing wrong with it, just noisy.

would there be prop clank or chatter when it's only in neutral?

[vandamit]

I did find a cut in a spark plug boot that i caused. would this effect anything though? 20200708_122632.jpg

[billnorman1]

would there be prop clank or chatter when it's only in neutral?

Mine was with a SS prop idling. In gear. Prop not loose, just something in the shaft making noise.

[vandamit]

I took a look today at the "new" plugs I had put in the boat and I only rain them 5 minutes or so but if you look at the one in circled in red it doesn't look like the others. Could be an issue, maybe again with the spark plug wires or something else. May not be anything, i'm racking my brain trying to figure it out though. plugs.jpg

[vandamit]

here are the old plugs. Anything look weird about them?old plugs.jpg

[billnorman1]

It seems odd the threads are dirty near the ends. Also, the new plugs have been drawn fully down, the gaskets are properly crushed. I like Champion plugs in iron heads but the threads are a little sharp for my taste in aluminum heads. You want well machined threads in aluminum. It almost seems the plugs might be a little long. Are those specified for your motor right down to all the letters?
Pictures can be deceiving, the plug on the far left looks oil heavy.

Your issue is noise, of they are the right plugs they should not make any odd noises.

[vandamit]

Update: found that a bolt had come out of the power head right above the #1 spark plug and had found its way under throttle cable. You could see where it had dug in even. 99% sure this was the issue. 20200710_174412.jpg

[TritonTRXV8]

did putting that bolt back fix your issue? That bolt has been out for quite awhile looks like the threads are not clean and kindof dinged up like its been rolling around down there for awhile.

[vandamit]

bolt.jpg
This is where the bolt came from. Picture is of the bolt after I found it and reinstalled it. I have no idea how long it's been out. I've owned the boat since it had 5 hours on it and I've never gotten even remotely close to touching that part. Hell I don't even know what that bolt holds or what that area is called? Only thing I've done is change the oil and spark plugs and had some lower end unit work done this spring.

[vandamit]

took it out last night and still sounds the same after putting new plugs and new plug wires back in and replacing the missing bolt. Maybe it doesn't sound that bad, it's running great! Had a guy tell me his did that after an impeller change so who knows.

[gatorglenn]

Hey, where your drive shaft leaves the Motor cowling and goes into the top of the lower uint. There is a black plastic washer on top of the pivot housing. See if it has popped out and slapping around on the drive shaft.