I bought a 2004 911 Carrera 4S in August 2014. The car had 54,000 miles on it and now has 63,000. I spent $3000 at the dealership to change oil, battery, belt, front CV boots & etc just to get a good start with the car. Ever since I bought the car I had noticed a growling noise somewhere in the front of the car that finally showed itself through a leak. I took it in to the dealer and they replaced the front differential. That was a $7100 repair bill. I don't have the time or facilities to work on this car but am committed to bringing it to first class condition. The car is tight and smoothe and I love it. I just wish it were red. Now that the front growling sound is gone, I now can hear what I think to be 3 noises in the rear of the car. I'm thinking there is the normal ambient noise of the road and the engine but I believe there is either tire noise and/or transmission/gear box noise. It seems worse at 35 & 65mph, but it's enough for me to say I can definitely hear something and it's noisy. I really don't want another $7100 bill. I know tires can be quite noisy but have a sick feeling that this probably isn't just tire noise. I also understand that these cars are not going to be "quiet", but what is quiet for these cars? I measured the noise level and it averages around 87db. The car has an automatic transmission and has Pirelli PZero tires. Can any of the readers of this give me some advice, clues, or guidance?

 

Without hearing this is difficult to help. Check the transmission fluid. And it could very well be the tires you are hearing.
Do you have a "stock" muffler, if not it could be drone from the muffler system you are hearing. Even stock mufflers drone a little.


Did the previous owner do any mods or is the car completely stock? If it's modded tell us what mods were done. When I changed the motor mounts and added transmission mount inserts the noise level went up until they all settled in, but it's still more noisy than stock.

 

Thanks for the reply! This car has not been modified at all and the muffler and tailpipes are original. I will take a look at the transmission fluid level. I do know that there is a delay in shifting when the car is cold, but after it warms up its all good. I may swap out the rear tires. Any suggestions for quiet tires? Another thing to mention is that there is a groaning sound when decelerating all the way down to a dead stop and I know it's not the brakes.

 

It's a great pity that you didn't buy an extended warranty along with the deal. I fortunately did and had a noisy gear box (Manual) which the warranty covered for about $5000. This being my first Porsche, I thought all Porsche's sounded a bit loud inside. NOT SO as this was pointed out to me via a Porsche Garage who changed the gear box under the extended warranty.. Yours being a TRIP should be OK therefore I go for the inside of the rear tires being well worn. Check them out....Rear tires wear more on the inside. Also check the engine mounts. Those are my guesses and the Mounts can be done as an easy enough DIY job for about $200. Good luck. Ask your question on Rennlist 996 forum. You will be helped more on that forum. An added note. I know bad engine mounts makes gear selection on a manual harder to select so I presume they could effect a triptronic in the same manner making the box sligtly out of line and noisy. Just a guess on that one but worth looking into and not very costly to remedy as a DIY job. Your engine mounts are probably due for a change anyway as preventative maintenance work.

 

My experience with Pirelli tires on my Boxster is when the tires get worn and hard from heat cycling they get noisy. In one case the tire noise masked a wheel bearing. Pirelli tires are good tires but they are the noisiest tires compared to Michelin, Continental and Bridgestone tires.

With my Turbo the front tires (Bridgestone in this case and not Pirelli) were making so much noise I had the car in the shop for a suspected wheel bearing problem and the tech told me it was the tires.

In the case of the Turbo the tires were noisy because the front tire alignment was out a bit. When I expressed some disbelief at this diagnosis, the tech had me feel the tread surface and sure enough I felt the feathering.

I drove the car home -- nearly 1800 miles -- and after getting the alignment corrected the tires quieted right down (after a hundred miles or so of driving scrubbed the tires in to the new alignment.)

In the case of your car I note you mention a noise when letting the car slow down on engine compression.

I'm no expert but often a noise appearing when doing this is a transmission/diff problem and not tire related.

What can you do? Be sure the tires are properly inflated. Be sure the alignment is ok. Feel the tire tread faces and check for feathering.

Have the car checked by an experienced tech. He should drive the car and be sure you tell him exactly how you produce the noises you are concerned about.

 

Yes, as soon as Pirelli tires start to wear they get noisy I'm running Kumho Excta and like them a lot. True, you'll usually go through 2 sets of rears for every 1 set of fronts. Do not run different brands front and rear, change all 4, check Tire Rack. Get an alignment and have them set a neutral toe and remove some negative camber, that's what I did and I now have 8k miles and little wear.
As for the groan, sounds like transmission, you could have the fluid changed and the pan filter cleaned. As far as warranty, this would be pre-existing so I doubt it would be covered, my experience with after market warranties is they try everything to get out of paying, never seen or had one that actually was worth anything. THIS IS MY OPINION.

 

Getting new Sumitomo tires tomorrow. I'll report how that goes and what changes I "hear". Thanks for the comments. I inspected my Pirelli tires and found both rear tires to be severely cupped in the inside of both tires.

 

4 new Sumitomo tires and an alignment solved my noise problem. The car is like driving a quiet, smoothe sewing machine now. The Pirelli tires were probably ok, but whoever installed them before I bought the car did not have it aligned which led to the demise of the rear tires which in turn caused the noises. All good now.

 

Great to hear it was the tires. I have an 04 C4S, had some of the same issues. Thought it was a wheel bearing, sure enough it was the tires. Put it up on a lift and the rear tires were severely worn on the inside.

 

It is amazing how much noise tires can make on these cars. And severely worn tires are the baddest of the bad.

I'm not exaggerating when I say new tires makes even my 2002 Boxster with now over 288K miles feel like a new car. The car is once again quiet and the wiggly/squiggly is all gone with the new tires fitted. While a set of new tires is not cheap the results are worth it.

Be sure you get a proper alignment. With the proper alignment rear (and front) tire wear should be even across the tread face and tire life with reasonable driving should run around 20K miles for the rear tires and easily double that number for the front tires.