993 exhaust flutter!
03-09-2003, 12:08 AM
#16
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I haven't replaced the mufflers. I bought the car about a 1 year ago and it came with the sound package mufflers. This problem started about 4 months ago and I have slowly ruled out all of the obvious. I have let three separate people listen to it but they all agree on one thing removing the exhaust or parts of it and ruling out each item. The tech at the Porsche shop had seen and heard the problem before. He also told me it wouldn't hurt the car to drive it that way but I would loose some power and take a chance of over heating the heads if I didn't keep an eye on it during the summer months when it gets hot.
03-09-2003, 01:20 AM
#17
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</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">R&R of the heat exchanger (aka exhaust manifold) is trivial. Yes, I've done it personally, this isn't fifth-hand opinion. Never, never take your car back to those people again.
Where are you located? It's not shown in your posts.
<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">R&R of the heat exchanger (aka exhaust manifold) is trivial. Yes, I've done it personally, this isn't fifth-hand opinion. Never, never take your car back to those people again.
Where are you located? It's not shown in your posts.
03-23-2003, 09:38 PM
#19
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I replaced the gaskets (crush rings) on the heat exchangers last week and that didn't do it. Skip in Denver told me the muffler replacement he made with the RSR mufflers corrected his flutter. My car has the sound package mufflers. Does any one else have these type of mufflers making this flutter? When I pulled off the heat exchangers the porcelain liners were in great shape as well. The two other options I received from some local Porsche mechanics were to check the smog pump which is located behind the intake (filter box) and or check the hydraulic timing chains on each bank. The chains could have slack during the down revs. The down revs seem to be when I here the flutter. The flutter does come from both mufflers. thoughts?
03-24-2003, 12:02 AM
#20
Jon,
Have looked into the loose material in side the catalytic converter theory? I have not had a chance to really look into my "flutter" I am going to do an oil change in the next two weeks and I think I will take off the headers then to look into the liner suggestion.
When you took of the headers to look at the porcelain liner did you shake the header around to see if there was anything in the tubes?
Have looked into the loose material in side the catalytic converter theory? I have not had a chance to really look into my "flutter" I am going to do an oil change in the next two weeks and I think I will take off the headers then to look into the liner suggestion.
When you took of the headers to look at the porcelain liner did you shake the header around to see if there was anything in the tubes?
03-24-2003, 12:27 AM
#21
I have this muffler flutter. I also have the motorsound option. I haven't paid much attention to iT though. Should I?
03-24-2003, 11:43 AM
#22
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Just some information I thought may be helpful to answer some of the muffler flutter sound.
I have noticed in many of the factory muffler the by-pass tube is poorly welded on to the internal tubes, especially true for the sports motor sound muffler made by Gillet and where the by-pass tube diameter is larger.
When I do the conversion for the RSR muffler I always had to touch up the factory welds in that area to make them stronger. A lot of times I notice the welds are not complete, just a couple of tack welds spots to keep the by-pass tube in place.
If the by-pass tube's welds break loose they will definitely make some flutter and rattle noise.
Below is a picture of the by-pass tube.
<img src="http://p-car.com/exhaust/mufflercomparet.jpg" alt=" - " />
I have noticed in many of the factory muffler the by-pass tube is poorly welded on to the internal tubes, especially true for the sports motor sound muffler made by Gillet and where the by-pass tube diameter is larger.
When I do the conversion for the RSR muffler I always had to touch up the factory welds in that area to make them stronger. A lot of times I notice the welds are not complete, just a couple of tack welds spots to keep the by-pass tube in place.
If the by-pass tube's welds break loose they will definitely make some flutter and rattle noise.
Below is a picture of the by-pass tube.
<img src="http://p-car.com/exhaust/mufflercomparet.jpg" alt=" - " />
03-24-2003, 08:47 PM
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The heat exchanger was clean and with no loose parts inside. I don't think this problem is a huge concern but since I have a cab it just anoys the hell out of me. I think the RSR muffler is probably the answer. Robin told me it sounds better than the sport muffler and for $450 I believe the quality job he does is as good as it gets. I did check the cat when the heat exchanger was off as best as I could but a new cat is $1900 or $1000 used. I've had cats fail on other cars before and the car usually has poor performance or stops running. It's last on the list. I'd rather buy new wheels. I do have the motor sound mufflers by Gillet.
03-24-2003, 10:03 PM
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Thought everyone with "exhaust flutter" might be interested in the following exchange with Steve Weiner or Rennsport Systems on this subject :
Hi Hap:
I have owned my '96 993C4 for three and a half years now. I've put about 15,000 miles on it in that time, and there are now about 56k on the car. The entire time I've had it there is an occasional noise that seems to come from the left side exhaust area. The car runs fine, and there is no noticeable problem with performance.----------------------
OK
There is a sound that some describe as an "exhaust flutter", others as something rattling in the cat or muffler, or maybe like baffling or heat shields buzzing. It only happens momentarily as the engine decreases rpm to near idle, or pulls away under load from idle.The noise occurs only in a narrow rpm band just above idle. I have never been able to actually locate the sound.---------------------
OK
The car has no modifications to the exhaust or engine. Trans. is 6 speed manual. My bottom engine tray has been removed. Seems like quite a few 993 owners have this problem, as indicated by the recent thread on "exhaust flutter" on the Rennlist 993 forum. Theories on the problem seem to include :ceramic valve seats broken, with debris rattling in the mufflers; loose muffler baffles; loose materials in the catalytic converters; heat shields rattling; and loose exhaust tips. Some think it comes from their right side exhaust, some the left. Haven't seen any reports from anyone who think it comes from both sides. Ever heard of this ? Have any idea ? Looks likes quite of few 993 owners would like to find the answer.---------------------
Yes, I have. The problem can be narrowed down by removing the rear bumper cover and running the car on a chassis dyno to locate the source of the sound.
You pretty much covered the various reasons; broken internals in mufflers or cats, loose or broken heat shields, and pieces of the ceramic exhaust port liners rattling around in there. You might need to remove a muffler or cat to confirm the diagnosis. Remember, these systems cross over each other so the left side of the engine's muffler is on the right and vice-versa. The cats are located at the very rear.
Its NOT uncommon for the ceramic port liners to break up and fall into the cat; this is a symptom of over temperature in the heads and insufficient oil cooling for what you do. We just finished another Rennlister's engine with that same problem and this requires new heads. Its NOT to be ignored,.........................
With some detective work, you'll find the source.
--
Steve Weiner
Rennsport Systems
Portland, Oregon
503.244.0990
E-mail: porsche@rennsportsystems.com
For Porsche High-Performance Solutions, Racing Components and Performance-related Information
Visit Rennsport Systems on the Internet at:
<a href="http://www.rennsportsystems.com" target="_blank">http://www.rennsportsystems.com</a>
Hi Hap:
I have owned my '96 993C4 for three and a half years now. I've put about 15,000 miles on it in that time, and there are now about 56k on the car. The entire time I've had it there is an occasional noise that seems to come from the left side exhaust area. The car runs fine, and there is no noticeable problem with performance.----------------------
OK
There is a sound that some describe as an "exhaust flutter", others as something rattling in the cat or muffler, or maybe like baffling or heat shields buzzing. It only happens momentarily as the engine decreases rpm to near idle, or pulls away under load from idle.The noise occurs only in a narrow rpm band just above idle. I have never been able to actually locate the sound.---------------------
OK
The car has no modifications to the exhaust or engine. Trans. is 6 speed manual. My bottom engine tray has been removed. Seems like quite a few 993 owners have this problem, as indicated by the recent thread on "exhaust flutter" on the Rennlist 993 forum. Theories on the problem seem to include :ceramic valve seats broken, with debris rattling in the mufflers; loose muffler baffles; loose materials in the catalytic converters; heat shields rattling; and loose exhaust tips. Some think it comes from their right side exhaust, some the left. Haven't seen any reports from anyone who think it comes from both sides. Ever heard of this ? Have any idea ? Looks likes quite of few 993 owners would like to find the answer.---------------------
Yes, I have. The problem can be narrowed down by removing the rear bumper cover and running the car on a chassis dyno to locate the source of the sound.
You pretty much covered the various reasons; broken internals in mufflers or cats, loose or broken heat shields, and pieces of the ceramic exhaust port liners rattling around in there. You might need to remove a muffler or cat to confirm the diagnosis. Remember, these systems cross over each other so the left side of the engine's muffler is on the right and vice-versa. The cats are located at the very rear.
Its NOT uncommon for the ceramic port liners to break up and fall into the cat; this is a symptom of over temperature in the heads and insufficient oil cooling for what you do. We just finished another Rennlister's engine with that same problem and this requires new heads. Its NOT to be ignored,.........................
With some detective work, you'll find the source.
--
Steve Weiner
Rennsport Systems
Portland, Oregon
503.244.0990
E-mail: porsche@rennsportsystems.com
For Porsche High-Performance Solutions, Racing Components and Performance-related Information
Visit Rennsport Systems on the Internet at:
<a href="http://www.rennsportsystems.com" target="_blank">http://www.rennsportsystems.com</a>
03-25-2003, 10:41 PM
#25
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I joined this site 30 days ago as a user and the information has been priceless. I signed up as a member tonight. I have one more piece of information for you to chew on. My car makes a flutter not a rattle. I've listened with my ear at the each muffler and it comes from both sides. The mystery to me is why it goes away on the rev down with the ac compressor engaged. I'm not reaching hear, this does happen. The flutter doesn't exist with the rpms below 3 with the compressor engaged and only slightly exists with the rpms above 3.
