Getting strange exhaust sound
10-10-2018, 01:43 PM
#1
Rennlist Member
Thread Starter
Getting strange exhaust sound
2014 981 S, 42k miles: I have a strange exhaust sound (at least I think it is exhaust). It sounds like a turbo prop plane, occurs at idle and under acceleration, increasing with RPM. I also no longer have the "crackling"when downshifting. No engine warning lights, no performance issues. Just very annoying and somewhat concerning. I'm wondering if the muffler has gone. I'm having my indy look at Friday. Anyone have any ideas? Thanks.
10-10-2018, 04:26 PM
#2
Rennlist Member
It'll be very hard to diagnose remotely period, but please post a video. Common causes for weird sounds are leaves in the intake or belt area, loose spark plugs, loose exhaust connections, and other worse stuff. Doubt the muffler has structural issues at only 42k.
10-11-2018, 09:00 AM
#3
A video would definitely help...
Where would your muffler have gone? lol
But seriously, the fiberglass packed in a muffler can burn up with time and allow the car to sound deeper and raspier. But it's a gradual change that you won't notice occur.
If a muffler fell off or you had a crack in the exhaust, you would definitely notice that. It would sound louder and you'd get even more burble noises when you let off the throttle.
Exhaust leaks or problems are pretty decipherable as an exhaust sound and not something else... If you're sure it's exhaust, the first thing I would check is that the headers are still bolted up nice and snug. A loose fit or blown manifold gasket can cause unpleasant noises like you're describing. It won't always trigger a CEL because higher flowing exhaust will still be passing by the O2 sensors as normal and the car may just start dumping more fuel to compensate for what it thinks is running lean. Any MPG change with this?
But a gap at the headers will allow a lot of exhaust to escape and prevent any glorious noise when lifting off the throttle. Can you smell exhaust coming from the rear wheel well areas?
As mentioned, also check the connection points between the cats and the rest of the exhaust.
But I would be more concerned about a random misfire (any pending codes that haven't triggered a CEL yet?), since a misfire will change your exhaust note. But you'd also feel the lack of power.
If something has gotten stuck in the belts, I would stop driving the car until you get a chance to look at it.
Where would your muffler have gone? lol
But seriously, the fiberglass packed in a muffler can burn up with time and allow the car to sound deeper and raspier. But it's a gradual change that you won't notice occur.
If a muffler fell off or you had a crack in the exhaust, you would definitely notice that. It would sound louder and you'd get even more burble noises when you let off the throttle.
Exhaust leaks or problems are pretty decipherable as an exhaust sound and not something else... If you're sure it's exhaust, the first thing I would check is that the headers are still bolted up nice and snug. A loose fit or blown manifold gasket can cause unpleasant noises like you're describing. It won't always trigger a CEL because higher flowing exhaust will still be passing by the O2 sensors as normal and the car may just start dumping more fuel to compensate for what it thinks is running lean. Any MPG change with this?
But a gap at the headers will allow a lot of exhaust to escape and prevent any glorious noise when lifting off the throttle. Can you smell exhaust coming from the rear wheel well areas?
As mentioned, also check the connection points between the cats and the rest of the exhaust.
But I would be more concerned about a random misfire (any pending codes that haven't triggered a CEL yet?), since a misfire will change your exhaust note. But you'd also feel the lack of power.
If something has gotten stuck in the belts, I would stop driving the car until you get a chance to look at it.
10-11-2018, 03:27 PM
#4
Rennlist Member
Thread Starter
Update: it's the alternator
Alternator bearing went bad, insides being chewed up; $1,795 installed (maybe a little less if they can re-use the exhaust manifold gaskets). Sucks. Hard to believe it would fail at 42k miles. I would attempt it myself but I simply do not have the time to invest right now.