earossi

While driving the 993 today I heard a large "clunk" in the front of the car. Sounded like I had hit some road debris. The sound was then followed by a loud "fluttering" sound. My thoughts were that I had hit something and that I had broken some of the plastic undercladding of the car and that I was hearing the loose panel resonating in the wind as I drove the car. Below about 30 mph the noise goes away. At about 35 the flapping sound comes back and increases in frequency and loudness with speed. Sounded like it was coming from the right front side of the car. I pulled over and took a look at the underside of the car and saw nothing obvious.

Since the car is lowered, it is not easy to see the suspension; so, when I got home, I put the car on a jack and took off the front right tire. Nothing obvious. All the plastic panels seemed intact. Drove the car and the noise is still there. Then proceded to pull the other three wheels off the car and inspected each wheel well. Nothing obvious. I am really puzzled.

Though the sound appears to be coming from the front right side of the car, it sounds like a have a piece of plastic wrapped around one of the CV joints. Problem is that there are no rotating parts in the front of the car except for the wheels.

Do any of you have any idea what this could be? A loud whacking sound that comes in at about 35 mph and increases in frequency and loudness as road speed goes up? Sorry for the vague explanation.

TMc993

It sounds as if something like a body panel or fender liner may be deflecting and vibrating or flapping as you get to a certain speed. If you haven't already done so, check your front air dam and make sure it is appropriately attached. Also, it may help to get a couple of friends to ride in another car (One to drive and one to observe your car) to see if there is something visually observable as you increase speed.

Good luck

T

Tonydec

I'd go over the tire very carefully, pulling/pushing on the tread portion. Last time I experianced something similar (though not with a Porsche), the tire tread was delaminating from the tire. We looked and looked, couldn't see anything wrong. Then all off a sudden, a series of bangs of a different frequency and it got quiet, then you could see the piece of tread coming out from under the rig on the road behind us. The 'out of synch' bangs were the detached piece bouncing around the fender liner before it got spit out.

earossi

Tonight I put the car up in the air on my lift and went over the suspension with a fine tooth comb. Only thing that I found was some missing screws in the plastic cladding on the bottom of the car and just in front of the right front wheel. The plastic parts were loose and I thought that I had found the culprit. Sourced some screws and reattached the cladding and took a drive.......whacking noise is still there.

You may have a good idea that if one of my new Michelin's is beginning to delaminate, that would explain the noise, even though there is no sign of anything rubbing in the fender well. So, tomorrow, I will take the wheel off the car and take it in to have it spun up on a tire balancer to see if there is a partial delamination. Don't really have a clue of what to do beyond that.

geolab

remove right front wheel
remove right front front plastic panel as you call it (wheel housing protection)
check what is obstructing the oil cooler fan, and rectify
while you are in there, check behind the cooler for leaves , debris, etc.
to do this, push bumper black grill to the inside, and clean debris.
might be this grill is unhooked and hitting something with wind
regards

P-daddy

Bearings, Ernie?

TMc993

If a tire were delaminating, would you not feel it through the steering wheel (Front) or seat of your pants (Rear)? And wouldn't it come on gradually instead of suddenly as described in the original post?

I agree with geolab...Something is probably flapping in the wind.

earossi

So, today, I swapped out the wheels one at a time for the emergency spare hoping to isolate the wheel that was the cause of the sound. Sorry to say that after swapping out all four wheels, the noise is still there. Not sure what to do right now. Any thoughts?

earossi

Nam,

The noise does not sound at all like a bearing. It sounds like a piece of loose plastic buffeting against the undercarriage. The noise is speed related. Silent until I hit about 35 and then it starts. Gets louder with increased speed. Does not make any difference if car is cold or hot.. Bizzar.

earossi

Geolab,

You could be on to something. The noise does seem to be coming from the right front side of the car. My concern is that the noise is there when the engine is cold as well as warm. I'm fairly certain that oil is not even yet flowing to the aux oil cooler, so would be surprised that the fan is operating. What did you have in mind?

Since I am at a loss for what it could be, I think I will take your advice and open up the area around the oil cooler. Not sure what to look for though.

TMc993

Warm or cold won't make a difference in the area geolab described...Air is moving through it regardless...Still sounds like the key to the noise is a certain level of wind velocity through that area which is then setting up a vibration or flapping of some type...

earossi

Agreed. I have the car on the lift right now and will remove the cladding covering up the oil cooler and take a look in the cavity. I'll let you guys know what I find, I am amazed at the amount of plastic in this cars.

P-daddy

Wow Ernie how many times in two days can a guy put his car on jacks, remove and replace parts? Lol
I did a lot of that this past winter.

Body Roll

I had a noise like this from the rear passenger side wheel area. It turned out the plastic fender liner was oscillating at highway speeds. I used double sided tape to damp the problem area.

earossi

The noise is exactly as you would expect if a plastic fender liner were loose; however, I have grabbed everything that I can get a hand on and none of it is particularly loose. I compared each part with its counterpart on the other side of the car and can't really zero in on anything.