My Yanmar 2QM15 whistles while it works...

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BobM

BobM

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Jun 10, 2004
3,269
S2 9.2A Winthrop, MA
Just bought a boat with a 2QM15. It runs fine, but is whistling at low rpm. I had a mechanic look at it but he had no clue either. I'm about to depart for a three day trip...any ideas? It seems to run fine and the whistling goes away when you throttle up. It is apparent at idle and isn't all that loud.

Thanks in advance,

Bob
 
B

Brian M H23

Intake system leak?

It could be a small leak between the air cleaner and the engine - sucking small amount of air through it?
 
N

Nice N Easy

Could it be a

Sounds like it could be a belt slipping a little bit at low RPM. This could sound like a whistle. Check the belt tension. If memory serves, a 2QM that is raw water cooled has two belts, alternator and raw water pump. Pretty easy to adjust. Other than that, I can't be of any help.
 
L

Landsend

Brian is right on...

Most engine whistling sounds come from the engine intake system. Try torquing the intake manifold and tightening the air cleaner
 
B

Brian M H23

A simple way to test

An easy way to test for air leaks: spray around the intake with WD-40 or another light solvent. if the engine revs up a little, thats your whistle.

I have to be careful saying that, because it's a trick used on cars. Be careful of fume build up!!!!!! have lots of ventilation.

The other approach is to mist water onto the intake, and see if the engine stumbles. This is safer but not as noticable when it works
 
B

BobM

Thanks for your answers

An intake whistle makes a lot of sense.

bob
 
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