Post seasonal maintenance vibrations

[jrhunt84]

So, just got the boat back from the shop for seasonal maintenance (oil change, fuel filters, spark plugs) and took it to the marine. Just wanted to run it for a little bit make sure everything was running well. Started up great, idles perfect, just has more of a slight vibration than I remember. Not enough that things on the boat are shaking but enough that I noticed it. Gave it some gas (on the trailer) and seemed to go away but at idle it had a little "shimmy".

The boat is a 2016 255 with only 85 hours on either engine and new impellers and wear boots last year thanks to a friend (former friend I should say) not paying attention to the tow rope.

Any thoughts?

 

[Luc Lafreniere]

And I presume it wasn't there before this maintenance? In other words, that damage was done, repaired and then you used it for a while with no issues? I mean, the only thing that could explain this from the maintenance is a bad spark plug. If one isn't firing well, it could cause a little vibration/stutter in the engine.

Usually any vibrations comes from the impeller area. Debris, uneven wear, etc. I know they didn't touch that, but I'd start by inspecting it through the grate. Get a good light source and have a very close look at the impeller and wear ring through the grate. You can also looked at it through the jet nozzle from the stern with a good light source again. If you want opinions, post good quality pictures of what you see.

But if it's not coming from the impeller, then any vibrations must be coming from the engine itself. I'd start with the spark plugs even if they were just changed.

 

[jrhunt84]

You are correct, we use the boat post impeller fix with no issues. I hesitate to think it's the spark plugs as their is no change in RPM's or sounds of a misfire.

I thought maybe it was the "chop" in the harbor as it was windy today but I fired it up out of the water and still felt it.

Again, it's not an alarming vibration, just not as smooth as last season.

 

[Luc Lafreniere]

Yeah, that's a toughy. I know personally, I had an odd vibration at idle that would go away at speed. About a month later, I got a misfire code and discovered I had a faulty spark plug. Replaced it, vibration and code went away.

Otherwise, not sure what could cause this.... sorry.