Mercruiser 470 Timing chain

M

mhicks

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Joined
Jun 15, 2009
Messages
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Do these tend to wear out? Does the tensioner tend to wear out? I just replaced a 470 motor in a boat I have and it seems to be making a slapping sound in the front half of the motor. When you idle it up a little it goes away. Sounds like a timing chain to me but not sure. I don't want to tear into it if I don't have to. Is this a common problem on these?
Mike
 
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dman4100

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Apr 14, 2009
Messages
10
Re: Mercruiser 470 Timing chain

I had a similar noise on my engine which turned out to be a bad rod bearing on number 4 cylinder.
 
M

mhicks

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Messages
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Re: Mercruiser 470 Timing chain

Thanks, it sure sounds like it is coming from the front of the motor and it doesn't sound like a rod to me. I can move all the way around the motor listening and it is definitely in the front (I think).
 
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dman4100

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Re: Mercruiser 470 Timing chain

I hear what you are saying, and hope that it is the timing chain for your sake.

I also thought the noise from my engine was coming from the timing chain or distributor. I changed out the distributor but the noise remained.

I dismantled the engine and found a bad rod bearing along with a leaking head gasket. The timing chain was fine.

This engine was over heated and had very low oil pressure which I believe led to the above issues.

I did have the motor rebuilt and also had to have the head replaced because of a crack into a valve seat.
 
CAPTKEV85

CAPTKEV85

Petty Officer 1st Class
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Mar 12, 2008
Messages
229
Re: Mercruiser 470 Timing chain

Its the tensioner on the timing chain. I put a new tensioner and chain and my slapping noise went away. It was easy on my boat took my 45 minutes to do.
 
M

mhicks

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Joined
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Messages
8
Re: Mercruiser 470 Timing chain

So, I guess that means you did it in the boat. Just pull the harmonic balance and the front cover off? Did you do your water pump seals while you were in there? How many gaskets did it take 2 or just 1? Mine just does it at low idle, was it that way with yours. Rev it up just a little and it goes away all the way up to WOT.
Thanks,
Mike
 
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