Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See Video

Jdiraff

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Hoping someone can help with this .

Was running my 1998 Force 120 today after re adjusting the carbs. It's starts right up and idles pretty good I guess, but at around 3,000 RPM's and higher , the engine started making a very loud, high pitched, metal chain like rattling noise.

I uploaded the video so you can see exactly what it is doing at after the 1:10 and 1:53 on the video on the video . I throttled down after since I thought I was going to blow something ?

1998 Force 120 - YouTube


Any input would really be appreciated ?
 
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roscoe

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Re: Can anyone tell what this grinding noise on my 120 Force at high RPM is ? See V

Re: Can anyone tell what this grinding noise on my 120 Force at high RPM is ? See V

Your telltale is showing very little water coming out !!

Not a good idea to run the motor that high on the muffs, you either have a bad water pump, or a poor water source, leak around the muffs.

Also a bad idea to run the motor that high, unrestricted, with no back pressure.

The noise, well, it could b a gremlin, or it could be a big problem.

A friend of mine had a motor that would make that type of sound occasionally, when running about 3500-4000 rpm.
We were never able to track it down, and he ran it that way for 10 years.


???
 

Jdiraff

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Re: Can anyone tell what this grinding noise on my 120 Force at high RPM is ? See V

Re: Can anyone tell what this grinding noise on my 120 Force at high RPM is ? See V

Pump is new and its pushing alot of water
Just cant tell on the video
As far as revving high on muffs, I agree with you .
I was , however, looking for a little more help in an explanation on what a possible diagnoses of that noise could be ?
 

foodfisher

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Re: Can anyone tell what this grinding noise on my 120 Force at high RPM is ? See V

Re: Can anyone tell what this grinding noise on my 120 Force at high RPM is ? See V

I couldn't hear any high pitched metal grinding sound. Sounded pretty ok to me. Things sound different with the cowling off.
 

Jdiraff

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Re: Can anyone tell what this grinding noise on my 120 Force at high RPM is ? See V

Re: Can anyone tell what this grinding noise on my 120 Force at high RPM is ? See V

I appreciate the feedback The grinding occurs at the 1:09 minute and again at 1:53 intervals on the video
Its pretty noticeable....can you take another look when you can?

I am really anxious to figure out what it could be... just don't wan't to run on the water and damage the motor.
Thanks very much

http://www.youtube.com/watch?feature=player_embedded&v=v6Vsnvofz74#t=49s
 
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Outsider

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Re: Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See V

Can't help you with the noise. No telling what you did the first time, and I'm sure it didn't get any better when you did it again ... :facepalm:
 

Frank Acampora

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Re: Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See V

Not sure if we are hearing the same thing!

When you run these engines at a high speed with no load and a not fully opened throttle, when you back off the throttle they will "four cycle." The reason is that as you back off the throttle suddenly, there is no load to slow the engine. it is turning too fast to get the gas it needs (at that RPM, with the throttle closed) to fire every revolution so each piston fires every other revolution just like a four cycle engine

Sounds like a heavy rattle as it backs down until it goes past a certain RPM, then she will smooth out and run two cycle again.

Sort of a ran-dan-dan-dan-dan-purrrrrr

While a 2 cycle engine is capable of turning very high RPM without damage, It is NOT a good idea to run them at high RPM with no load as this lack of load will also translate to oscillating forces on the pistons and bearings when you back off.
 

Jdiraff

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Re: Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See V

Thanks Frank

Could you listen again ? https://www.youtube.com/watch?feature=player_detailpage&v=v6Vsnvofz74#t=66s

Its the loud noise that starts at around 1:09 seconds on the video, when I throttle up...it's pretty loud, stays consistent until I back down...goes again at 1:53 at the end of the video
Its pretty distinct abnormal rattle which you can't miss. almost like a loose chain thrashing around inside.

Someone had told me might be a blown ring or perhaps even a worse crankshaft bearing , which will really upset me to hear
Gonna check the compression tonight ...One thing for sure is I wont rev that high anymore while out on muffs
 

Jdiraff

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Re: Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See V

Runs and sounds fine when back under 3k RPMS
 

foodfisher

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Re: Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See V

HEARDIT!, also at 1:25. To me it's something exterior rattling due to the unloaded higher rpms. Put the cover on and go boating.
 

Frank Acampora

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Re: Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See V

Fisher, you are a better man than me! I listened 5 or 6 times and simply did not hear the described noise.
 

foodfisher

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Re: Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See V

Crank up the volume. Sounds like a loose nut or something laying in the pan or linkage rattling. Might be a loose bolt with the washer rattling. Not what I would call high pitched.
 
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roscoe

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Re: Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See V

Sounds like a loose metal plate, rubbing up against the flywheel.

Like I said, my friends boat did this a few times a year, for a decade. We He was very worried, but we could not track it down.
 

jerryjerry05

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Re: Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See V

What was the end result when setting the carbs? How many turns in/out?
Should be at 1 turn or very close.
Does it do it in the water?
 

Frank Acampora

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Re: Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See V

Ah Yes! I heard it now. I was listening at night and could not turn up the volume. With the speakers all the way up it sounded loud and clear. (Doesn't help that I have a high frequency hearing loss)

That is definitely an external rattle and not an internal worrisome thing. It could have a couple of causes: The Bendix may be rattling on its shaft. That would be my first suspect.--I looked closely and could not see it rising into the flywheel so no worry there.. The trigger may be rattling in its cage (under the flywheel). The electronic mounting plate may be vibrating against something. Etc. Etc. Etc. Auto mechanics HATE rattle complaints. They are difficult to find and stop.

At any rate, the engines do vibrate more with no load and I would bet that under load she would run through 3000 right on up to 5000 with no rattling noise.
 

RRitt

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Re: Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See V

for whatever it is worth. my port engine had a rattle over 3500rpm when loaded. never ran muffs except to flush. The engine was also hard to start.

after full carb clean and synch the rattle went away and the engine started on first lick. I believe the rattle was carb jets incorrectly adjusting mixture to air flow. As RPM increased one of the carbs was running lean? after a good evening with pipe cleaners and carb solvents everything was perfect and no more rattle. Probably not the problem here but since i don't have decent audio ... it is my first thought and nobody seems to have mentioned it yet.
 

Jdiraff

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Re: Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See V

Thanks Everyone, your feed back is very much appreciated ..the Fact that every-one seems to think its external is great news to me and my wallet :) I was afraid it was a blown piston ring or crank case bearing ?
Most importantly, didn't want to damage anything and make it worse.
Frank, please forgive my lack of knowledge, but how can I identify the Bendix, Trigger, and Electronic Mounting plate to see if that is the cause of the noise.

Jerry, ...I followed your suggestion at reset the carbs as per you direction. Right now, they are both sitting at approx 1/8 out, past initial setting. Shes running better than she was, but still experiencing RPM jumps. I have not dropped her in the water yet, but plan to do so Friday or Sat at the latest to make the final adjustments. I'll certainly post the results, also try to get another video .

Jeff
 

Jdiraff

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Re: Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See V

https://www.youtube.com/watch?featur...snvofz74#t=66s

So I trailered the boat, trimmed all the way out, around 70 miles or so to a friend to help-out with the motor.
When he started it, the above noise had seemed to completely disappear...Does anybody think its possible the whatever was making that awful noise got dislodged or something ?
 

cuenta

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Re: Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See V

we can't see the video

maybe the gas be mixed well with the oil LOL.
 

foodfisher

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Re: Can anyone tell what this rattling noise on my 120 Force at high RPM is ? See V

https://www.youtube.com/watch?featur...snvofz74#t=66s

So I trailered the boat, trimmed all the way out, around 70 miles or so to a friend to help-out with the motor.
When he started it, the above noise had seemed to completely disappear...Does anybody think its possible the whatever was making that awful noise got dislodged or something ?

Very likely it vibrated to somewhere else. Look down the motor leg. It's going to be a part that's NLA. :lol:
 
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