If I let off gas to coast at 70 mph or so car will whistle. Only happens under coasting. No sounds under acceleration etc. What can it be. I have an idea but want unbiased opinions off the top of your minds first. Thanks for any help.

 

Does it sound like wind blowing through something or does it sound like metal on metal?

If wind, check your cowling and make sure your windows are rolled up all the way. If metal, check your bearings.

Edit:
If it's only happening when you're coasting, you might want to check your air filter. If it's really dirty, it could be wheezing when your foot's off the accelerator.

 

Sounds like a vacuum leak.

 

Vacuum leak, which is why you only hear it during coasting, when the vacuum is highest.

 

Wouldn't he be throwing a CEL if it was a vacuum leak big enough to cause a whistle you could hear from the inside of the cabin? I mentioned air filter because it's in front of the MAF, so it wouldn't register as unmetered airflow. I've heard those things howl before as well.

 

Not always, double check around the plenum and intake tubing.
Have you had any work done recently that could have bumped into a hose...etc?

 

whistle tips..... joking

where does it sound like it is coming from?

 

I was so tempted to post that video when I read the title.


Must resist.....

 

 

Like an alarm clock....WOOTWOOOOOOOOOOOT

 

Sorry hadn't had a chance to get back to you. It sounds like it is coming from under the car, but to me it sounds like air, but if truly metal what bearings are you talking about? The only work done recently 6 months or so was I had a 3.9 fd installed with all the differential bushings. Also have a knock when moving from a stand still.

 

the fd may not have been shimmed properly

 

I wondered the same but figured that if it was shimmed incorrectly, sound ought to be continuous and it should have been happening ever since corrections were made which did not occur like that. The sound developed later. Will be taking car in tomorrow and if the shop is incapable of fixing it, then to the stealership I will go.

On a side note the sound is very much like the video but God I am hoping its not audible to everybody else.

 

carrier bearings, not shimmed right... all sorts of problems can come from the diff. my buddy had a carbonetics diff and that bish whined so bad

 

Thanks for all the help guys. Once this problem is solved I am done modding this car. She runs awful nice and I don't have the heart to go through the effort of cams at this point. She will go into the garage as I save for what I hope to be a Q60 in the fall.

 

Car is a vert and after checking and checking of various components must come to conclusion it is the top causing the whistle. Can find no leaks etc but sound different to non existent at different temps. My last check on a day its warmer than freezing I will check at speed with top down. I suspect noise will be gone. Just thought I would update. Thants to previous poster who mentioned this.