Volvo Penta 8.1L Whistle

[golf101]

Second 8.1 question of the day:

I test drove a boat with an 8.1L engine. Never driven one before, but it had a distinct whistle (best description I can give of the sound). The dealer said that was normal for 8.1 and Mercrusier 496's because they suck so much air in. Just checking for some verification that this is accurate.

The sound didn't bother me that much, but, if you wanted to, is there anything you can do about it?

 

[Fun Times]

Re: Volvo Penta 8.1L Whistle

Second 8.1 question of the day:

I test drove a boat with an 8.1L engine. Never driven one before, but it had a distinct whistle (best description I can give of the sound). The dealer said that was normal for 8.1 and Mercrusier 496's because they suck so much air in. Just checking for some verification that this is accurate.

The sound didn't bother me that much, but, if you wanted to, is there anything you can do about it?

Is the Whistle at mid cruise speed, Say 3000ish rpms???

 

[Philster]

Re: Volvo Penta 8.1L Whistle

Can be very normal and common.

High performance intakes let the air in freely and don't do much to restrict it. It can be so distracting that some auto makers actually make an effort to quiet the whistle on the high performance intakes at the expense of some power, and it's common for owners to replace these intakes at the expense of hearing the whistle again.

It (the whistle) is very obvious when the exhaust is not open or thru hull, or if it is, the thru hull exhaust is run out mufflers. A quiet exhaust will let you hear the intake whistle, or sucking sound.

 

[golf101]

Re: Volvo Penta 8.1L Whistle

Is the Whistle at mid cruise speed, Say 3000ish rpms???

It seemed to be more pronounced in the mid cruise speed range, but I began to notice it even before then.

 

[Fun Times]

Re: Volvo Penta 8.1L Whistle

It seemed to be more pronounced in the mid cruise speed range, but I began to notice it even before then.

Newer MerCruiser 496 engines should not do that anymore, But I do not know if Volvo fixed this.

To stop the Whistle MerCruiser had to pop rivet on a special air diverter plate to both sides of the throttle body plate, Because the plate was basically cutting the air as it went into the throttle body and giving it a very loud whistle sound.

To verifie this you would need to remove the flame arrestor at cruise and put you finger on the throttle body plate and see if the Whistle goes away.

That is how I found it, I put my finger in the one o'clock area and the Whistle would go away, I gave MerCruiser my idea of a fix and they ended up doing something like it to stop the whistle sound.