A new noise started today. My car almost sounds like a an old VW or motorcycle. I'm thinking it might be the exhaust gasket between the manifold and turbo.

When there is enough pressure, about -10PSI on my gauge, the noise starts. The frequency of the "fluttering" sound does not seem to increase with RPM, but it does get a louder under acceleration.

I'm going to check the exhaust/turbo gasket now, but does anyone else have any other thoughts?

I took a video and I have a microphone in the engine compartment.

EDIT: Also, this morning a cylinder was misfiring. I pulled over and found one of the spark plugs was loose. I tightened back up. I'm not sure if it this is possibly related or not, if it is not the gasket and is something else.

 

I'm kind of curious to know why there's a gasket between the manifold and the turbo in the first place.

 

I could see part of the gasket earlier, but it wasn't until I started removing things that I could verify the gasket is completely there. Or at least all of the outside edges that I could see all the way around.

I got the gasket last year as part of troubleshooting a different noise and at the time Brain said to put a gasket there.

I put everything back together and decided to see if I could replicate the noise while stationary and I could not. I then put it up on stands to see if getting the wheels to spin while in gear could replicate the noise. It did not.

I looked underneath the car and the exhaust is bolted tight all the way from front to back.

I'm going to put the car back down now and drive it again and see if it still does it.

 

Ok, so putting everything back together and going for a short drive, it still sounds the same.

However, I've only had about 6 hours of sleep the last 60 hours and my brain is just not the same right now. The misfire this morning sounded so different than what I was used to. After I fixed the plug, the "normal" sound didn't sound right to my exhausted brain. I've been wondering off and on all day if it really was different or if it normally sounded like that.

For now, I'm going to get some much needed rest and consider it normal.

 

Well the turbo won't create much boost unless it's under load. And under load I suspect your blowing out a weak part of your head gasket, perhaps between two cylinders or something. Sounds like mine when I had a blown head gasket, although the audio with your mic and my laptop speakers isn't phenomenal.

That being said, mine was still slightly noticeably sick in idle and neutral.

 

That sounds like a loose spark plug to me. Had that happen to me(in a ford Mod motor.. imagine that!) while at Nationals. Didn't know what it was either, and drove me nuts for about 24 hours before it blew out. Tone like a lifter tick, but fluttered like a rod knock. Couldn't figure it out until it let go completely.. 1200 miles from home.. in a rainstorm... the first one they had in 6 months. Thankfully there was a local dealer to fix the issue permanently and the plug went back in long enough for it to get to the dealer.

 

Thanks so far.
Quick question: if it is loose, like the one I found yesterday, couldn't I just tighten it back up? You said something about having to go to the dealer for a permanent fix...

 

Spark plugs are all tight. The noise is definitely new. My clothes have a stronger exhaust/gas smell today than normal.

 

No the threads were banged up enough from the plug fluttering that it wouldn't take a proper torque.

 

I took another video with my phone. You can best hear the noise around 14-17 seconds and 24-27 seconds. The road was little rough and there is extra wind and road noise. Sorry.

 

I usually find exhaust leaks by looking at/hearing the exhaust...

 

Are we thinking it is an exhaust noise and not an engine noise (spark plugs, head gasket, etc.)? I'm just asking, because I do have some difficulty hearing and I am also still learning about working on cars.

If you remember my "whistling turbo" thread from last year, I thought it was exhaust/air noise but it ended up being the turbo (bearings?).

I am not able to duplicate the noise while stationary and the speed of the noise might be changing with RPM.



Thanks!

 

to me it sounds like the typical exhaust pulsing/tapping/ticking

 

That is what I thought too, but I am always open to hearing other opinions.

 

that or a bad valvetrain

 

can't tell if serious

 

I've been dealing with a random noise for the past few weeks. Try listening around in the engine bay with a stethoscope with the end removed or even a piece of hose should work. If you can hear it idle, or revving it in neutral, just listen in different areas with a stethoscope and you should be able to narrow down where the noise is coming from.

 

Two updates:

1. I have a mechanic's stethoscope and I could not tell any difference from one cylinder to another. They sounded the same at the top and side. My other car which I am getting a "new" engine in, because it's under warranty, has very different sounds at the top and bottom for one cylinder.

2. I did the soap bubble test to look for leaks and I did see a small leak between the exhaust manifold and turbo, where the gasket is. The leak is smaller than last year when I had the "whistle" issue.

I first noticed this sound started Tuesday morning, after tightening the loose spark plug causing a misfire. I did have an autocross on Sunday and did not drive the car Monday.

I'm not sure if the small leak described above would be causing this noise. I can try and get it fixed since it is there, but the suddenness of the noise makes me think it may be something else.

 

I found the problem. I noticed one of the welds looked funny on the exhaust manifold. And then one of the copper nuts was completely black. The exhaust is blowing out there. Even one of the bridges on the manifold separated.

After taking the manifold off, I could see the crack in the weld went all the way around.

See the attached pictures.

 

wow.... according to the pics, the actual WELD broke... thats crazy... usually it will break around the weld... not through the weld itself. are you gonna re-weld it? or try to find a new way to disperse the weight across the whole manifold more evenly?