1993 Mercruiser 3.0L Engine Rattling Noise

Jwally

Cadet
Joined
Oct 15, 2012
Messages
26
Hey all,

I have a 1993 Mercruiser 3.0L where the engine has never given me any major problems. When I first started it up for the season I noticed a noise coming from the water pump bearing, so I replaced the water pump. Now, it is making a rattling noise coming from the belt bearing area which speeds up when I rev the motor. I am hoping it is just a bad harmonic balancer (bottom pulley) but that might be optimistic. Take a listen to the video and give me your ideas. The link is below


Thanks in advance for the help.
 

Rick Stephens

Admiral
Joined
Aug 13, 2013
Messages
6,118
Pull the belts off and fire up for a minute or so. See if the sound goes away. Or use a stethoscope and listen to each belt driven component.
 

NHGuy

Captain
Joined
May 21, 2009
Messages
3,631
The balancer pulley looks to have runout. Perhaps you can remove the belt and torque the bolts. Might be able to avoid removing the mount,engine, etc.
 

Jwally

Cadet
Joined
Oct 15, 2012
Messages
26
I ran it without the belt and these was noise, so it seems to be the balancer pulley. I didn't see any bolts holding it on, just tapped threaded holes to remove it. I smacked it on all around with a block of wood and that seems to have seated it better, the noise has ceased. I ran it on the lake today with no issues. I'll keep an eye on it, but I'm sure a replacement is in my future. Thanks for the help.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,465
I ran it without the belt and these was noise, so it seems to be the balancer pulley. I didn't see any bolts holding it on, just tapped threaded holes to remove it. I smacked it on all around with a block of wood and that seems to have seated it better, the noise has ceased. I ran it on the lake today with no issues. I'll keep an eye on it, but I'm sure a replacement is in my future. Thanks for the help.

Ayuh,.... If the balancer has started to delaminate, Change it Now, not later, after it destroys abunch of expensive parts,.....
 

Jwally

Cadet
Joined
Oct 15, 2012
Messages
26
OK, I have ordered a new balancer pulley and will install it next week when it arrives. Looking for a little help in the removal/install procedure. I'm guessing I get a balancer removal tool which threads into the three 3/8 X 24 holes, and then turn the center bolt until the pulley is removed. The instructions state to remove the torsional damper retaining bolt. I can't see one, I think mine just slip fits on. Is this correct? If not, where is it? Once I have the old one removed, clean up the crankshaft and keyway with steel wool, and lightly lubricate with oil. Then apply RTV to the keyway, and knock the new damper on with a hammer and block of wood. Will it be obvious when the damper has fully seated, or how will I know? Anything else I'm missing?

Sorry for all of the questions just looking for a little guidance from the pros.

Thanks.
 

Newbie@boats

Chief Petty Officer
Joined
Apr 6, 2010
Messages
536
When I removed mine to do my timing cover, you need to remove the front motor mount, I used a 4x4 piece of wood with 2 ratchet straps to support the motor, use the puller and it popped right off. Do what you said apply oil clean off the crank to ensure a smooth reinstall it will be pretty obvious when you bottom out the pully just use light taps and it should slide right on. Install motor mount and you should be good. Possibly checking the alignment after removing and reinstalling the front mount
 
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