Mercruiser 470 rear motor mount

sgille

Cadet
Joined
Jun 1, 2011
Messages
6
I just had my rebuilt 470 put back in the boat and it runs great above 1400 RPM, below that it has a clunking sound that sounds like a motor mount with no rubber insert. After investigating I found the fiber washer is above the motor mount attached to the motor not between the motor and transom mount. What does the fiber washer do and could this be where the sound is coming from. When I shut the engine off I will hear one or two loud clunks as it comes to a stop. Any thoughts would be a great help.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Mercruiser 470 rear motor mount

Glad you noticed it, could have cost you a coupler.
You need to put the parts back in in the proper order. then re-align the engine.

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sgille

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Joined
Jun 1, 2011
Messages
6
Re: Mercruiser 470 rear motor mount

Thanks for the reply. Does the motor needs to come back out or can I remove the outdrive and lift the motor to put the washer inplace? Do you think that is what is making the clunking?
 

Bamaman1

Lieutenant Commander
Joined
May 15, 2011
Messages
1,895
Re: Mercruiser 470 rear motor mount

1. You will need to spend a couple of minutes pulling the outdrive.
2. Make sure the above picture is followed. You might have to lift the engine slightly.
3. Insert the alignment tool that looks like a spline shaft. You will adjust the elevation of your front engine mount until the tool goes in and out easily.
4. Replace the outdrive.

The rubber coupler is designed to self destruct if the engine and outdrive are not perfectly aligned. Hopefully, it's still okay.
 

sgille

Cadet
Joined
Jun 1, 2011
Messages
6
Re: Mercruiser 470 rear motor mount

So what is the purpose of the fiber washer?
 

Don S

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Aug 31, 2004
Messages
62,321
Re: Mercruiser 470 rear motor mount

So what is the purpose of the fiber washer?
Prevents C from banging into D in the above picture.

The rubber coupler is designed to self destruct if the engine and outdrive are not perfectly aligned.

False..... :facepalm: It is not designed to self destruct, that's just how the coupler breaks when not installed or run properly.
 
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