best muffs to use on mercruisers?

pae0332

Seaman
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Jun 8, 2017
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tpenfield

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The water spraying out the sides of the muffs is the excess water that the drive does not need. You should notice less spray when the engine is running. You will probably never get 100% tight seal.

I use the rectangular-shaped muffs since they fit the outdrive inlet holes better than the round ones.
 

Chris1956

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Mar 25, 2004
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gee i always used whatever cheap ones were avail. water spraying is pretty normal. when you first start the motor, most of the water will be pulled into the drive, until the block fills, then it will start to spray a bit. that means it is working.
 

airshot

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Jul 22, 2008
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My muffs are over 40 years old and have always worked very well. Neighbors have bought several newer muffs and have had issues with them.
My guess is the newer models are not made as well as they often ask to borrow mine. Yes, the excess water will spray out from around the muffs as mentioned, as long as enough water gets in to cool your good. Muffs are designed for idle or mabey fast idle speed, NOT for high or wot throttle speeds. And muffs do not test the water pump as the pressure from the hose can give a false impression that the water pump is working.....
 

Scott Danforth

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Water should spray out about 10 ft until you start the motor
 

bajaman123

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I've found the 'dual feed' models to work far superior to others. Some boats aren't finicky at all about taking water, some will almost DEFY you every time. These muffs take care of all types.
 

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kenny nunez

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Jun 20, 2017
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The genuine Mercruiser ones are the best in my opinion. Whenever I had to use the other ones I always wrapped a bungee cord around the flushout just to make sure it would not slip down and burn up the pump. I learned that the hard way.
 

Lou C

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Nov 10, 2002
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Agreed I like the genuine Merc ones, I used to use the dual inlet ones from Tempo and others and what I found was the rubber was too stiff to conform to the shape of the lower unit. The Merc ones are made out of much softer rubber. As soon as the engine starts the water quits spraying out the sides. The trick with those is to get them on really snugly.
 

airshot

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Jul 22, 2008
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I've found the 'dual feed' models to work far superior to others. Some boats aren't finicky at all about taking water, some will almost DEFY you every time. These muffs take care of all types.
If my old ones ever fail, the dual units look like they would work great. I don't have high hp big block engines that use volumes of water, so will hang on to mine for now. Many that my neighbors had troubles with were the square units, heard more than a few complaints on those.
 

Jeff J

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Jun 23, 2021
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I just tank it using a large tote. I did have to build a 2x4 frame around the top to keep the weight of the water from deforming the tote.
 

Grub54891

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Jun 17, 2012
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I agree that the rubber is too stiff on some of them. I’ve had to duct ape on a set to get enough water to go in the drive. I quit using those.
 

crazy charlie

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May 22, 2003
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I have had Mercruisers with outdrives for over 30 years and never had an issue flushing with any muffs, they all work fine for an outdrive.The best seal I have ever had ,if thats your concern, are with plastic body with rubber cups fed on one side. For winterizing thru the drive I always duct tape the cups on leaving a slight 1"gap at the top of the cups which will allow excess water to escape without blowing off the duct tape job prior to switching over to AF which is drawn thru the drive and not forced.....If you get what I mean.Charlie
 

pae0332

Seaman
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Jun 8, 2017
Messages
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yeah well the mercruiser ones usually hold up but i am finding i need to replace them more often then i expect to . at 50 bucks a set it gets ridiculous
 
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