VIBRATION

[GNX231]

Hey all my starboard engine runs perfect how ever vibrates and shakes quite a bit as compared to the port engine. it is also slightly louder. i suspect the pump housing is swelling or maybe the pump needs a rebuild. but i'm not sure. do these pumps have to be aligned with some sort of tool? i'll give you a little history on this boat. i bought it last july and it has 130 hours on it and is in excellent condition. the dealer said he rebuilt one of the pumps however i can't remember what side. my first time out on it i sucked up something and it cleared itself after a few minutes. since then i have noticed this vibration. if i'm at the dock i will start just the starboard engine and listen a watch. i then shut it off and start the port engine it is smooth and quit. the starboard vibrates the whole boat.

 

[Andy S]

I would look very closely at the starboard impeller, my guess something, probably very small, is stuck between the impeller and housing.

Check out this for ideas, https://jetboaters.net/faq/i-think-...k-in-my-pump-engines-dont-get-to-full-rpm.61/

 

[Julian]

I agree with Andy....and if it is clear....when were the plugs last changed. I had a similar problem with an engine and it turned out to just be bad plugs.....I discovered this after pulling the pump and checking its condition (great condition)....then scratched my head, changed the plugs and voila....solved.

 

[itsdgm]

X2 on what is posted above. Could be as simple as a small piece of fishing line stuck on the pump shaft. But my next step would be to change the spark plugs. I've had similar vibration issues fixed by simply changing the plugs.

 

[GNX231]

Ok great thank to all. I will give it a look later today. I did change the spark plugs and ha no change. I wasn't aware that that cleanout plugs had to be changed and could cause problems.

 

[Cobra Jet Steering LLC]

Anything at all, even some fishing line will cause what you are experiencing. So what everyone else said, check the impeller

 

[GNX231]

if this was say the manhole plugs since the port side is fine if i switch the plugs from one side to the other the problem should move then correct?

 

[Scottintexas]

I don't think anyone was meaning the cleanout plugs but you could certainly try it to help isolate the problem.

I would ask the dealer to check his records to see which pump was "rebuilt" and what that process consisted of. Rebuilding a pump is a very generic phrase, where they chasing a cavitation issue and just took it apart and resealed everything?

I would tell you to also look for any loose sealant around the intake, you may have to reach up from underneath through the grates but I had some bad vibration because of that.

Does the vibration go away after you get on plane ?

At this point I would also fourth what was mentioned above, if no visual sealant is missing, visually check your impeller (maybe even remove it, it only takes 20 minutes), then move on to spark plugs and then a more thorough sealant inspection. How do your impellers look compared to each other, any obvious dings ?

 

[GNX231]

as far as the impellers go just from looking in from both under the boat and thru the nozzle. everything looks ok. never looked at the sealant. on plane the vibration smooths out. i did change the spark plugs with no change to the vibration. i guess i assumed they meant cleanout plugs haha.

 

[Scottintexas]

if it was my boat, since you changed the spark plugs already I would
1. call the dealer to see if it's the same side they fixed and if so what was the problem they were trying to solve and what did they do,
2. pull the impeller just to see if it is some fishing line
3. check the sealant in the pump to see if any of it is missing or you can easily pull it away by hand

I had some bad cavitation because of loose/missing sealant, at low speed I thought the engine was going to shake the boat apart and then it would go away at speed,
I doubt the cleanout plug is going to be the issue, normally that just causes a loss of thrust and not vibration.

 

[GNX231]

Ok I guess I will check out the sealant then and see what it looks like. I did have some cavitation but discovered the bucket was not fully open on both sides. Fixed it and obviously didn't help this problem. 4200 sealant is the stuff for this job I take it??

 

[GNX231]

SOMETHING I JUST THOUGHT OF. THE VIBRATION IS PRESENT IF I START THE ENGINE WHILE OUT OF THE WATER, SO IT COULDN'T BE CAVITATION CORRECT?

 

[Scottintexas]

ah, the little facts that help us, correct, if you are out of the water sealant and air induction won't be the issue.

I would pull the impeller out, it's an easy job, check the faq for detailed guide and you tube video,

 

[GNX231]

COOL MAN THANK YOU. i will pull it hopefully in a few

 

[GNX231]

ok i assume the shaft just slides out with the pump assembly but its not moving. however the impeller house moves about 2 1/2 inches so i think the pump need to be rebuilt i assume this is where the vibration is coming from.

 

[txav8r]

The whole back half of the pump with guide vanes and its own house, along with the shaft and impeller slide out. If it is moving 2.5" your almost loose.

 

[txav8r]

This will help...

 

[Scottintexas]

https://jetboaters.net/threads/yamaha-jet-pump-disassembly-from-grant-browne-youtube.446/

I wouldn't say you need a pump rebuild yet, did you look at the link above, the second you tube I think is the best,

is the impeller moving with the housing?

 

[txav8r]

Sorry @Scottintexas , I was typing and loading at the same time you were...

 

[Scottintexas]

https://jetboaters.net/threads/yamaha-jet-pump-disassembly-from-grant-browne-youtube.446/

I wouldn't say you need a pump rebuild yet, did you look at the link above, the second you tube I think is the best,

is the impeller moving with the housing?