High pitched whistle from engine at speed
 

I've had my boat (2009 MB with PCM 343 engine) about 4 years and last year really started to notice a high pitched whistling sound from the engine at about 20+ MPH. It's not extremely loud, but it's moderately annoying.

My (independent) mechanic said it's just the air passing through (something? I'm an idiot with engines and didn't catch exactly what he said), and that it is normal and not something that can be changed.

Just wanted to get other opinions on this. It seems very strange that this is "normal".

My dealer closed a few years ago so I don't have another expert to ask.

A high pitched whistle would make me think of a belt squeak or bearing noise on the belt's run. It might also be something like a fuel pump. I do not think it would be an air noise.

Mine whistles at just above idle. Its the air passing through the throttle body.

Yeah I think that's what the mechanic said it was.

Do you hear it at higher speeds also? Or only at just above idle?

I'd probably pay a lot of money to make it go away... (not "new boat" money).

Check the shaft seal. A few of us are having problems with it lately. Check mbboatowners.com and search for PYI shaft.

if you had the boat 4 years and it did not do it before then something is up. what that might be is hard to say without hearing it.

I *think* I didn't notice it before last year, though I had so many other issues I was dealing with I'm not sure.

x2 on the throttle body. I think whistle = air related. I'm wondering if you've built up the perfect amount of tarnish/crud in your throttle body and/or butterfly to make it whistle. Try a can of carb cleaner or brake parts cleaner, spray it on a rag, and wipe it all out (including the butterfly) as best you can...? Orrr maybe something in your exhaust has come loose just enough make a leak/whistle when the RPM's are up a bit...? Best bet is to put on a "fake a lake", fire her up in the driveway and have a listen...let us know when you figure it out!

Try pushing the hose to your air filter on tighter and check the other end of same hose to make sure it is seated at the valve correctly.

Thanks. I'll be at the boat this week with the mechanic so we'll check it out (I'm way too ignorant to check that stuff myself).

The problem doesn't happen at the low RPMs I've gotten the engine up to while the flush kit is hooked up on land. I forget the RPMs where it starts, but it's around 20MPH

I get the "whistle" just above idle as well.. its more like a very high pitch squeal.. like when you run your finger around the rim of a wine glass.. sounds like metal on metal to me

And it's only "just above idle" for you? Not at higher speeds like mine?

that's right.. id say right about 1000 - 1200 rpms

Call PCM, they may send you a throttle body spacer which will fix the issue, if it is air delivery related.

I had a strange whistling noise at around 2800-3200 RPMs on my 2011 Malibu VLX with the Monsoon 350... the dealer thought I was crazy, but if you sat in the back seat you could definitely hear it, and it was very annoying to your ears unless the stereo was cranking.

They got rid of it by totally replacing the intake manifold, it was air delivery related, once the new manifold was installed the high pitched noise stopped. I sold the boat with 253 hours and never heard it again once the manifold was replaced.

John, did you change anything to your boat last year when you started noticing the whistling?

Did you have any type of service? Change props?

When I went to the OJ Cinco prop, it was so much quieter and smoother that I immediately noticed engine noise, both intake and exhaust, a lot more.

I don't think I had anything other than standard services, and no prop change last year. I did upgrade the prop a couple of years ago. But I've had a Fresh Air Exhaust the whole time, which cuts engine noise so the whistle would have been noticeable always.

I have the same thing. It's just air flow relatedNBD has done it since new at 2k-3.5k

I've got a 2010 Nautique with the 343 and mine was making the same whistle. I remember going on the Nautique site...finding others with the same problem and I took it to the dealer. It was a fix or recall with something with the throttle...I think. Let me seach some of my old stuff and let you know. It was only at a certain RPM and it was really annoying. It's gone now. Not sure I agree with all the "air passing" comments.

Ken

Found it on Planet Nautique. It is a spacer for under the throttle body on the 343. Gets rid of the whistle. Here's the link if it works. There is a picture of the spacers in the thread. I believe this is what fixed mine also...I'd have to check my shop receipts but I'm sure this was it.

http://www.planetnautique.com/vb3/sh...engine+whistle


Ken

Props to (thedude) above...I see now that he actually called it correctly....:)

Last night I submitted a request for one of the throttle body spacers on the PCM web site's contact form. This morning I had an email saying they'd send it out today.

I won't know if it works until 2 weekends from now, since my mechanic won't be at the boat until Monday (he's also going to clean the throttle body).

Thanks very much for all the advice here... I'll report back hopefully in a couple of weeks.

Forgot to reply back on this... the spacer DID fix the problem. Nice not to have that whistling sound anymore.