Yanmar 4JH4E Whistle

[Bill Marrero]

I have a 2006 Hunter 41AC with a Yanmar 4JH4E 650 hours that whistles from approx. 1200 to 1800 rpm. It does not seem to occur when there is no load on the engine. I've adjusted the stuffing box and changed the fan belt. Has anyone had this occur and found a solution? I have a friend with a 2004 Catalina 40 with the same engine and he also has the same whistle.
Any thoughts of what the cause might be would be appreciated.
Thanks

 

[Jake N Eggs]

Does that engine have a turbo charger on it? Turbo's sometimes develop a whistle at certain speeds due to the air movement past the turbine blades. Check for a restriction at the air cleaner.

 

[Don Lucas]

I have the same engine and don't have a "whistle". Have you checked your alternator and belt?

 

[KD3PC]

usually a leak in the air system to the engine/turbo.

 

[Bill Marrero]

Thanks for the reply's, I don't believe the engine has a Turbo as I see no evidence but I will double check and there is no air filter on this engine just a air mixture box with no filtration. Belt just replaced alternator is quiet. My friend with the Catalina removed the air mixture box on the engine and installed a custom air filter set up on his and it was still giving him the same whistle at similar rpm's.( I intend to install a similar set up )
Bill M

 

[Don Lucas]

Thanks for the reply's, I don't believe the engine has a Turbo as I see no evidence

It doesn't, those that said it were just throwing replies.

Have you asked Yanmar your question?

 

[splax]

Hello,
When the engine is under load, it is using more fuel and more air at a given RPM. It seems to me you might have an obstruction or restriction in the air passage that perhaps is vibrating like a reed in a saxophone until the airflow becomes great enough to push it back flat against the passage wall. It could be an internal coating that has separated from the metal.
Just a thought.

 

[SEMPERAVANTI41]

Have the same boat and engine. Does not have turbo. Buy a Mechanic's Stethoscope ($4.49 at Harbor Freight) and use while engine is running and under load to pinpoint location of whistle. Also, perhaps you could disconnect v-belt for short run and see if problem goes away.

 

[Marc14857]

Interesting, I have the same engine and I do get a distinctive squeal (not sure I would call it whistle) at those general RPMs. No turbo, did check pulleys for bearing wear, and just replaced alt belt. Still have the same sound. Id be interested to hear if you can isolate the sound.

 

[Don Lucas]

I wonder it is a seal on a cover etc. from air flow. Does it keep whistling if you open the cover?

 

[Bill Marrero]

Thanks again all, I've confirmed it does have not a turbo and the noise only occurs when in gear. We adjusted the stuffing box to no avail and replaced the fan belt. I will try to get a better location this weekend with a listening tube and mechanics stethoscope.

 

[Don Lucas]

the noise only occurs when in gear. .

Did you check the gear oil level? Does it have the right oil in it?

Have you send the info to Yanmar yet?