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3queens
09-14-2007, 06:02 AM
have takin out the slip in mufflers,when in drive hear a vibration from the exhaust? could also feal it in the floor had rpms at 850-925 i have about 30hrs
on the motor no mods. if i bump past it to 1000 rpm goes away?
any and all input is appreciated!!!
thanks and tgif
p.s did not have this when exhaust muff in place

LHC30Victory
09-14-2007, 06:07 AM
my engine mounts came a little loose and caused similar feelings of vibration....not related to exh but check anyway maybe the installer forgot to tighten the jam nuts..

cobalt222
09-14-2007, 06:22 AM
my engine mounts came a little loose and caused similar feelings of vibration....not related to exh but check anyway maybe the installer forgot to tighten the jam nuts..
u may have flappers in the exhoust system that keeps water from intering the system when sitting in the water.my boat dose the same thing at low rpm.sounds like something comming apart.put ur hand on the pipe to see if u can feel it towards to end of the out let

jojoshow
09-14-2007, 06:54 AM
Yes, that is true. We removed the exhaust mufflers and installed the dana shorties with the flap. At low rpm it will rattle. It freaked me out too. Check everything else out just to make sure. But that sounds like the problem.

Beer-30
09-14-2007, 06:57 AM
Below 1000, the flappers are clanging in the tube. Above 1000, they are held away from the pipe.
I just took a long chisel and knocked off the weld on either side of the flapper. Removed the metal ones and left the black rubber ones on the end.
Mercruiser demands two forms of reversion protection for warranty. One is sufficient.

3queens
09-14-2007, 04:41 PM
the flappers are external just wrap around outer pipe tip
did not have noise when mufflers in
possible ecm reaction to less back pressure?:confused:
or just paranoid
but there always watching

Trailer Park Casanova
09-14-2007, 04:54 PM
my engine mounts came a little loose and caused similar feelings of vibration....not related to exh but check anyway maybe the installer forgot to tighten the jam nuts..
Yep Engine mounts.

Throttle
09-14-2007, 05:00 PM
baffles / flappers :idea:
normal

Throttle
09-14-2007, 05:03 PM
while motor is at idle, pop hatch, place hand on pipe and you can confirm the vibration and feel the flappers...

Throttle
09-14-2007, 05:05 PM
listen carefully...
hope all is well with you and the girls, c ya soon!

Beer-30
09-14-2007, 06:55 PM
Also, you can reach in from the back and flip the flappers up and down inside.
In addition to making your boat smile, you can usually verify the metal/metal sound.
Mine HAD it. I had them knock off an additional $500 in case it was something serious. He said the rattle had been there as long as he remembered. I found it was the internals and knocked those puppies out. Much better now.

3queens
09-15-2007, 07:56 AM
thanks for the input i am leaning toward motor mount
or connections on exhaust around riser
we will be at moabi on sat the 22nd
hope to see peeps
thanks cam. everyone well hope to see you and j soon!!:)