I bought my 2006 roadster knowing that it had a pretty loud whistle with the top up that starts around 40 MPH and eases up a bit (still there) around 65. When the top is down....no whistle. I wasn't too concerned figuring that I could zero in on the source. Original owner said it always whistled. First thought was the seal along the top of the windshield or around the side windows. Its one of those sounds that seems to come from the front of the interior but most of the time seems to come from anywhere. Here's what I have tried to narrow down the cause:

• While the whistle is sounding...put both windows down....no change
• Tried alternately opening either door.....no change in whistle
• Took an old necktie and laid along top of windshield seal before clamping down top....no change
• Tried tie between lower rear edge of top and the tonneau cover...no change
• Attempted to lay plastic wrap (Glad Wrap) over the top frame above windshield down onto top of windshield.....still whistled and pretty quickly blew loose.
• Looked for holes/gaps in firewall....nothing obvious
• Got a mechanics stethoscope that came with a rubber horn attachment to listen for air leaks while wife drove......could not zero in a sound increase in any given spot

Am considering:

• the incoming air source vs an exit vent, valve relief...not certain how that works.....maybe whistles when interior pressures build up at speed?
• Possibly a bad air filter or fit under engine cover?
• Maybe bad cabin air filter?

Any ideas? Has anyone experieced this? Found some old posts that never mentioned a resolution. I'm running out of things to try. Any thoughts appreciated........great forum.....have learned a lot reading thru it all.

 

Also should add that whistle occurs regardless of fan/heat/ac setting. Any thoughts?

 

Is the whistle only happen when you're driving or even when it's sitting with engine running? I would check the cabin filter and the housing. The filter housing vent gets leaves and other debris in it that could be making the whistling.

 

I had this noise when I stupidly capped off both ends of the big hose from the driver's side valve cover to the throttle body.
The hose was deteriorated, figured I'd cap it off till I got a replacement.
I thought it was a water pump going out.

 

Only whistles when moving @ 40 mph and up.

 

I'm only guessing but I suspect it has to do with a gap somewhere between the windshield and the windshield surround moldings . . . Do you know if the windshield has ever been replaced?? Take some plumbers putty (or something similar . . . Play Dough? or just 2" wide tape) and pack / seal around that whole area. Drive the car and see if that stops the whistle.

Opps . . . I just re-read your post and see that there is no whistle when the top is down. Probably not what I thought . . .

 

I would get some painter's tape and tape around the windows and across where the top and windshield meet to eliminate those areas first.

 

Good suggestions......I'll try some painters tape or play dough around windshield......worth a try.

 

Use the blue painters tape . The adhesive will not leave a gummy residue if left longer than 6 days (unlike the green painters tape).

 

Update....After a couple weeks of top down weather I almost forgot I had a whistle. Then a week of rain, before I could get back to trouble shooting. I used blue painters tape where glass meets windshield frame on all fours sides. Then also taped along top edge of windshield frame where it meets rubber. Took a quick run down the highway and.......no whistle!! Hot Damn! I then started removing tape and driving and finally isolated the whistle within an 8-10 inch stretch centered above the rearview mirror at top of windshield frame where it meets the rubber that mates up to the leading edge of the top. Now I'll take a closer look at that rubber during daylight to see what needs to be done. The previous owner said they listened to that whistle since the car was new. Dealer never could figure it out. Looks like I'm close now.

 

THANKS for posting an update. Please be sure to let us know the final outcome / solution . . .

 

I suppose the altered air flow pattern causes the whistle to go away with the top down ?

 

I'm guessing it's air flow disrupted or maybe air getting past rubber seal and whistling at top latch? Just returning from weekend away w/o Crossfire.

 

I am a brand new owner ( 1 week) and it is very comforting to see folks helping out each other. All in all is the Crossfire a pretty reliable car? I have a 2004 coupe

 

Maybe the latch isn't quite pulling the top all the way closed.... Try pulling down on the latch handle while driving....putting more down pressure on the front seal.

 

I now see the problem. With the top down you can better see the strip of rubber that meets the top edge of the upper windshield frame. That rubber is tight to the frame all the way across except for an 8 inch stretch in the middle. Hard to even see, but tape on that section stopped the whistle. I'm trying to see if that rubber is held with adhesive. I don't see a channel to push it into and it does not look torn or damaged. I don't see this strip mentioned in the service manual either. I may try a thin line of adhesive.

 

Glad you got it figured out.

 

Here is the gap. You can see where the card can slip thru.

 

If you decide you need to replace that rubber I may have one. I'll look when I get home tonight.

EDIT: I was preparing this post just as you were posting your photo. Sorry I don't have that rubber molding. Looks to me like you could just seal that entire gap area with silicone sealant??

 

Welcome to the forum! You will find a lot of good info here as well as many helpful members who have had years of experience with the Crossfire. As for reliability, there is a list of common problems/issues with these cars somewhere here on the forum. Search for it and read up on the older posts on the subject and you will find that these cars hold up well. (mechanically they are Mercedes after all is said and done). There are quite a few here with well over 100k on these cars.