Clean your throttle body muffler 8.1 guys!

mnm99

Well-Known Member
Oct 2, 2015
2,445
Long Island
Boat Info
2004 340 SeaRay Sundancer
Engines
Twin 8.1 Merc
I never knew it existed. A friend of mine that is a marine mechanic mentioned it to me. I was getting 750rpm idle on my port motor longer that my star. It would take a long time for it to kick down after warm. He said to check my Muffler in my throttle body? Huh..Well I did and this is what it looks like. 420hrs, replace yours guys. Cost me $3 for both motors.
https://www.wholesalemarine.com/muf...h4fcl8QHDzWsUmu5pWJ_872STTnAxVpQaAgC7EALw_wcB
Gotta clean those blades too..


muffler.jpg
muffler1.jpg
muffler2.jpg
 
Yep I change them out each year as part of the annual maintenance. If they block, you'll need to replace your IAC. For this reason my merc tech suggests leaving them out.
 
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I block the valve open with a soft handle screw driver, hit the blades with a blast of carb cleaner, scrub the blades with a tooth brush, and rinse with another carb cleaner blast. Takes about 20 seconds.
 
Thanks, just ordered mine just in case - i havnt even checked them
 
Yep I change them out each year as part of the annual maintenance. If they block, you'll need to replace your IAC. For this reason my merc tech suggests leaving them out.
It makesa terrible hiding sound when their out...not to mention all the crap ends up in the IAC valve.
 
Interesting note, that the previous design on the mefi ecm's have no muffler and the IAC rarely fails.
 
It makesa terrible hiding sound when their out...not to mention all the crap ends up in the IAC valve.

Agreed the muffler quietens things down. As for the 'crap' that ends up in the IAC valve is also ending up in your motor, so you'll have bigger things to worry about.

I clean my bilge twice a year, clean my flame arrestor annually and change my mufflers annually and haven't had an IAC valve failure yet.

My merc tech recommendation was merely aimed at prolonging the life of the IAC valve and pointing to the reason for their failures. Yes, I've left mine in because of the noise without.
 
Remove your flame arrestor and it's located at the 12 o clock position looking at your throttle body. Grab some long nose pliers to pull it out as its only an interference fit.
 

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