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Whine from front (belt side) of engine


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About 5 seconds after I start the engine (340 Monsoon with 250 hours) a high pitched whine begins at the front of the engine (V drive so stern of boat).  It sounds like it's coming from the water pump or raw water pump but I cannot isolate it.  It is very high pitch and is a constant volume, it does not begin soft and ramp up.  It is not the fuel pump or the notorious intake whistle.  Could it be the alternator or one of the pumps?

Any ideas?  Do I have a part going bad?

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28 minutes ago, MadMan said:

You could temporarily remove the belt to see if the noise goes away.  Or use a rubber hose as a stethoscope to try to isolate it.

Already tried the hose but I could not pick up anything on any non moving parts.  Next step is belt removal.  I was doing some internet searching and found references to pcv valves making the same sound.  Anybody know where the pcv valve is on a 340 Monsoon?

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Anything with a bearing.  Removing the belt will tell you if it is alternator, engine circulation pump or idler(s) if there are any.  Doesn't rule out the fresh water pump since it is crank driven.

 

PCV if there is one would be in the valve cover

Edited by oldjeep
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6 minutes ago, oldjeep said:

Anything with a bearing.  Removing the belt will tell you if it is alternator, engine circulation pump or idler(s) if there are any.  Doesn't rule out the fresh water pump since it is crank driven.

PCV if there is one would be in the valve cover

Thanks.

The pitch doesn't seem to change with rpm so I'm suspecting (hoping) it's not a bearing.  Found a few easy ways to check the PCV on auto sites. Will do that on Friday.  Belt removal should be easy, if necessary, but getting it tight again might not be.

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  • 1 month later...
16 hours ago, mswsetter00 said:

Minnmarker, did you find a solution to your problem? I am having an issue with my boat. 

mswsetter,

Yes, I did.  See the 8/27 post in this thread:

I hope your solution is simpler.  Eliminate everything else first and use the carb cleaner technique in the above thread to confirm.  If it is the same, Bake's should have the gaskets.  You'll need tools and about 4-5 hours to fix.  I found some utube videos on intake manifold replacement in 5.7 GM engines which were helpful.  Doing a boat was actually a lot less involved since there are no power steering, air filters, or air conditioning things in the way.

Good luck.  That whine sure was annoying.

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