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

[jerryjerry05]

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

I was out tinkering with my twins.
Started my stbd.motor and it did something like that.
I believe it was a no load situation and and wouldn't have done it in the water.

 

[Jdiraff]

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

Here is the link again...
1998 Force 120 - YouTube

I thought about the no load, and I am sure its part of it, but i don't hear it on any other Force 120's running on muffs, so I imagine it is my specific motor
Gonna look down the leg 0) to see if anything came loose. Gonna check the compression, drop it in the water, and going to sync the carbs on a load
I'll update what I come up with.
Also, the RPM jump seems to be minimized by 1/4 turn out further on both Carbs. That puts them around 1 1/2 turns out
Jeff

 

[Jdiraff]

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

Update...

Took her on the CT River this afternoon
Its seems the adjustments to the carbs and putting her under load was all that it needed.
From WOT, she runs smooth as can be, got her up to 37 mph , 5k rpm no more noise, not more bogging out, no more RPM jumps.

So, the upper carb is 1 1/4 turns out, the bottom at 1 1/2.

Thanks for your help everyone !

Oh, one more thing, when I got back to the dock, she started leaking fluid from the bottom of the trim motor( pinkish , milky fluid) Unreal.....right ?

They sell some after market trim motors on ebay for around 165.
Mercury Mariner Force Tilt Trim Motor 120 120HP 1990 99 | eBay
I can also try to replace the seals as the motor seems to work fine.

Any suggestions? Anyone know the part # or where I can find the seal kit ?

Jeff

 

[grininmonkey]

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

I have an 97 125, just got a used boat with the Force on it. I have been fighting a low idle and engine cut off for a few days. Cleaned the carbs and it appeared to maintain an idle (using muffs at home). Went to the lake and and experienced the exact same noise between 3000 and 4200 RPM. When I first heard it, I pulled the throttle back thinking I blew something up. I kept running it for a while and also experienced a a WOT issue where it would run (what seems fine) for a few minutes and then start to have big RPM dips and act as if it was about to sputter out. I took the cowl off, looked for anything loose but could not find anything. The noise sounds really bad to me and has me worried as well. But another issue that bugs me, is after running for a bit... it will only hold an idle in either gear or neutral for 30 seconds or so. I had to re-start many times while moving in a no wake zone getting back to my trailer.