my 1997 993 has developed an exhaust flutter on the left side. You only hear it when the car is at idle and you rev it up. The noise is apparent from the back pressure. The car runs great with no problems. One porsche mechanic listened to it and thought it might be lack of tension on the timing chain valve. The other conclusion was in the muffler or cat. This car has only 15,000 miles and performs great but I can't find this annoying noise. Would a loose baffle in a muffler or a cat make this kind a noise? <img border="0" alt="[offtopic]" title="" src="graemlins/offtopic.gif" /> comments or recommendations please!

 

Jon;

Can you tell if the noise is from the tailpipe itself. Make sure that your muffler is engaged on the mounting bracket. Your heat shield can make noise if bent. I would assume that your mechanic checked this.

 

the entire exhaust has been checked. It doesn't make the noise when cold. the car has to be driven 10 minutes. you can rev it up to just 1500 rpms and when you let off you hear the noise. tut,tut,tut,tut,tut. You can't hear while driving only when you've stopped or in my case when I back it in the garage.

 

Jon:

My car, a 96 C2, makes exactly the same noise, except it comes primarily from the right side, only slightly from the left side. Like your car, my car makes the noise only at idle when warm. I described the noise to the mechanic as a flutter, just like you have. I had a good independent shop check it out but they could find absolutely nothing wrong with the car. The mechanic called the Porsche tech line or help line (I'm not sure exactly what it's called.) and was told by the guy on the other end of the phone that he had chased the same problem on another car but never found anything wrong. The consensus between the two was that the flutter was probably caused by the overlap in the camshafts because they run a lot of lift and a lot of duration. The also assured me that if anything was wrong with the engine that the OBDII system is sensitive enough to detect the problem before it got too serious. They said that individual variations between engines probably explained why some make the noise and some don't. The car runs perfectly and has made the noise for the year that I have owned it. I just try to ignore it.

Anyone have any other ideas?

Regards, Rob.

 

Rob: I was considering putting fabspeed mufflers on to enhance the sound and gain the 10 horsepower they claim. I wonder if this would enhance this noise? Do you think this conclusion of your mechanics is similar to mine? He actually thinks the hydraulic valve that puts the tension on the timing chain is not working properly and when you let off the gas the chain is making the actual noise and sending it through the muffler. The car has a separate timing chain for each side. you can see the timing chain covers just above the exhaust system on the block. He figures 2 hours labor and removing the exhaust system to check this theory before repairing the valve. This procedure can be fixed without removing the engine.

 

i have the exact same problem that occurs in the exact same situation. I was thinking about getting the fabspeed muffler as well in hopes that it would rid of the stupid noise.

 

I have no idea what it is, but my 96C4 has it too. The noise has a metallic sound, like loose baffles, or a vibration of a heat shield. Can't find it either. Only makes the noise when pulling away from idle.

 

sounds like an epidemic. It's ironic that I posted this message and in two days 3 people have the same problem but no one at the Porsche dealership or Porsche shops have ever heard this annoying noise.

 

Jon, if you do a search this noise is not unheard of and has come a couple of times. I have been chasing a noise that sounds very similar to what you are describing for the last year. Here is a previous discussion on the topic:

<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic;f=3;t=002144#000002" target="_blank">http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic;f=3;t=002144#000002</a>

I have also traded a lot of email with various people about this. I have yet to discover a good solution. My local mechanic thinks that the “honeycomb” material in side the catalytic converter is the cause. He says the material can come loose inside and causes the “rattle” or “flutter” sound. The local dealership also basically of agrees with this assessment. My local mechanic is very good Porsche mechanic but does not have vast amounts of experience with the 993 as there are not many in my area. I hope to have some more information after the Visit in the beginning of May because I am going to have some people with vast amounts of knowledge take a listen. My biggest fear is the cracked head scenario that is detailed in the above thread. So far I have no other support for this scenario other than the individual from the email list which I traded emails with a couple of times.

 

I just added the RSR muffler's to my '98 993 convert and they sound perfect. Easy to self install too. Regards, Pat

 

I went to the local Porsche dealer this morning and let someone new listen to my car. The dealer assures me that it's the exhaust gaskets at the head. They charge $105 an hour and claim this is an eight hour job. I counted 9 nuts on each side to remove the header from the block and the cat and don't see eight hour job. They continued to try and sell me an extended warranty for $3000 for 4 years. They told me to wait 30 days and then come back and claim this problem under the warranty. The gaskets only cost about $100. Has anybody removed the headers on 1997 993 and how do you get those nuts back on? What is the degree of difficulty?

 

What a honest dealership you went to...They want to sell you a warranty on a car they know to have a problem and then to claim on the warranty later on?
Does your local BBB know them very well? Or perhaps PCNA knows this dealership too?

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by jon glover:
<strong>I went to the local Porsche dealer this morning and let someone new listen to my car. The dealer assures me that it's the exhaust gaskets at the head. They charge $105 an hour and claim this is an eight hour job. I counted 9 nuts on each side to remove the header from the block and the cat and don't see eight hour job. They continued to try and sell me an extended warranty for $3000 for 4 years. They told me to wait 30 days and then come back and claim this problem under the warranty. The gaskets only cost about $100. Has anybody removed the headers on 1997 993 and how do you get those nuts back on? What is the degree of difficulty?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">8 hour job??? hahaaha <img border="0" alt="[hiha]" title="" src="graemlins/roflmao.gif" />

 

A question for Bass933,

Did you have this noise before you replaced the mufflers?

Maybe Robin can answer if he has seen many internals on the mufflers he has taken apart to be loose/rusty/etc. BTW, I also get a exhaust noise...I am betting its the mufflers since they have 70,000 miles on them. They are not that much quieter than RSR's though!

 

wait, how many miles are on your mufflers? I think this is an age/usage type of situation because mine have about 60k miles on them, and someone has 70k. I don't know how to respond to the guy who has 15k though...