Motor Sounds

[__ScottyDont]

So...my port motor sounds like a race car where my starboard motor sounds like a tonka truck and has some vibration in the handle. Tomorrow I'm changing plugs as routine maintenance but what else can I look at to see what could be causing this? I know silicone around the pump is a potential culprit. I want to nip this problem in the butt tomorrow, there's warm weather to be enjoyed.

 

[ToddW850]

So you are referring to it doing this while in the water, correct? Did you fog your engines this past winter? And have you taken it out since winter?

If you're on the water, missing silicone will not give that symptom. The missing silicone would make it cavitate and rev higher. But anyway, you're doing it right by changing the spark plugs first. That's where my money would be. Also wouldn't hurt to check the air filters for oil. JUST in case of an overfill of oil during the last change. Again, that would apply if this is the first time you've taken it out since then. But also check your impellers for anything caught up in there, like a small piece of wood or something. I've heard of that too. Good luck.

 

[Seadeals]

Are you running on the hose or on the water? Did you fog? How long since you last started (prior to noticing it was rough)? Was your fuel tank topped and treated? When you pull plugs, you will likely have some evidence if spark is your issue. Can missing silicone make an engine run rough? Think it may just impact thrust/rpm/speed. Check air filter for good measure, or run without it to see if it smooths out.

 

[__ScottyDont]

Yes, this is while in the water earlier today. I've taken the boat out ONCE last weekend but it was a quick ride from the ramp to the house. I did fog but that's burned off by now. Fuel tank was topped and treated. Last season I always remembered this motor being a little deeper, but definitely nothing like this.

 

[ToddW850]

Are you running on the hose or on the water? Did you fog? How long since you last started (prior to noticing it was rough)? Was your fuel tank topped and treated? When you pull plugs, you will likely have some evidence if spark is your issue. Can missing silicone make an engine run rough? Think it may just impact thrust/rpm/speed. Check air filter for good measure, or run without it to see if it smooths out.

@Seadeals Pretty funny how closely our answers matched. But for the record mine was first, HAHA

 

[ToddW850]

@__ScottyDont then it very well could be your plugs. See how it runs after you change. But also wouldn't hurt to check the air filter. Sounds like your gas should be good if you topped off and treated. Also because it's only affecting one engine.

 

[Seadeals]

That is pretty funny. Your wasn't there when I started. Nice work beating me to the punch!

 

[__ScottyDont]

Whelp, changed the plugs and got nothing, still have the deep sounds and heavy vibration. The oil filters looked dang near brand new. I'll look up in the intakes in a little but preliminary checks showed me nothing in their either.

 

[ToddW850]

Dang. Okay, there is something (I can't remember specifically) that can be switched between the motors to see if the problem transfers to the other motor. It's coils or something. Dang it! I can't remember, but I"m headed out the door. I belive @itsdgm knows what it's called. Hopefully he can chime in. Sorry.

 

[__ScottyDont]

I'll try moving coils over one by one today and see what happens. I still need to change plugs on the other motor so this will be easy. Next step after that is yank the pump and see if anything is hiding in there or what my impeller looks like.

To be honest, as an I/O guy the majority of my life until a few years ago, it sounds like a bad bearing.

 

[Glassman]

Whelp, changed the plugs and got nothing, still have the deep sounds and heavy vibration. The oil filters looked dang near brand new. I'll look up in the intakes in a little but preliminary checks showed me nothing in their either.

You didn't mention if this happens at idle, in gear and moving or both?
Could be a fuel issue, I'm thinking clogged injector? Have you taken a fuel sample?
Try a can of Seafoam.

 

[__ScottyDont]

@Glassman yes, you can somewhat notice it at idle. But really kicks in when you start throttling up and around ~3k rpms is the roughest vibration wise and then smooths out more ~7k rpm's but definitely still noticeable.

 

[Glassman]

Ok, could be an injector issue. You'll see if the problems don't transfer to the engine after you swap all that stuff out....

I like to take the path of least resistance, which is usually through my wallet, I would dump a can of Seafoam in there (if I was certain my jet pumps were clean and not the issue) before swapping out parts, etc. But I'm lazy

 

[__ScottyDont]

@Glassman With this application, I would assume all of it in the fuel would suffice

 

[Glassman]

1 oz. Per gal.

http://seafoamsales.com/clean-fuel-injectors-or-carburetor-jets/

 

[Lextacy03]

Maybe the start of captivation? How do the impellers look?

 

[Magic]

I would look at the pumps/impellers/wear rings first, then injectors.... Does the motor make full RPM? That might rule out injector failure..... Seafoam can never hurt so throw that in there too....

....Im still thinking pumps/impellers first........

 

[__ScottyDont]

Motor makes full rpm, hard determine if it's making full performance

 

[Magic]

Motor makes full rpm, hard determine if it's making full performance

Full RPM usually equals full performance, does the boat pull to the right? Might do that if the starboard motor/pump is compromised.....

Occasionally the pump liners swell and make too much contact with the impeller that can make quite a racket in the lower RPM bands....

Also if the motor is making full RPM, a blown injector and/or bad coil is most likely not the problem.......

Let us know how its going!

 

[__ScottyDont]

Update: I swapped out all the coils and no change. I took the pump off and everything looked clean. Could use a little silicone and possibly some grease around the shaft. Still sounds like a tonka truck. Also dumped in some Seafoam but haven't run the motors yet. I would assume that would fix the injectors over the duration of the first tank of fuel if that was the problem.

Any other suggestions?