Azraely

Hey Everyone,

I started noticing a noise inside the cabin, particularly after the car is warmed up, on the freeway if I accelerated under load at about 4000rpm. It sounded kind of like a hollow metallic pining or something..

I checked it in the garage, and when the car was idle and cold I didn't really hear it. If I revved it to about 3500rpm I could hear the noise. As the car continued to warm up while I was trying to listen to the mufflers, cats, etc I noticed the noise becoming present at lower revs, coming on around 2500rpm.
I finally took a video with my phone on the ground, upon playback I can make it out at idle, but I think only when it is warm, and its very noticeable when revving it.

Here is the video

https://www.youtube.com/shorts/CEqW1eyuwVQ

So far I've knocked the mufflers and cats with a rubber mallet, I don't hear anything rattling around.

My plan is to try the following the next chance I get:

• Remove the belt and listen to see if the noise is still present. Would it be ok to rev to 3500rpm with the belt off?
• Remove the rear bumper and heatshields to isolate a rattling heatshield
• I have my old stock mufflers and some cat bypass pipes, so can swap out the various components to isolate the issue. This would be easy except for what I assume will be plenty of rusty hardware as I've daily driven the car through 6 Alberta winters now.

Looking for any ideas or thoughts on what else to check for.

pdxmotorhead

Exactly how a failing cat converter sounds. You can pressure test with a vacuum gage the pressure before the cat should be nearly 0.
Easiest way is to remove the 02 sensor and use a adapter to extend the sensor out and drill a small hole in the adapter/extension to push the vacuum gage in to.

The "Spark Plug Fouling preventers" that folks use to fool the 02 to non realize its cats are missing is the one I use. cheap on flea-bay.
You need to drill the end out where the 1/8 or so hole is so it allows the pressure to get in.

Azraely

I figured it was the cats, but most of the threads that talk about them failing that had videos, they are no longer available.

I'm going to spray some liquid wrench on the bolts over the next few days to let them soak.

Azraely

I had to put chasing this down onto the back burner for the past month or so as I started suffering from low voltage once my car got up to operating temp. I had to order a new voltage regulator and y cable. Luckily that solved the problem and it wasn't the alternator itself.

Anyways, tonight I finally got back to the exhaust noise. Since I already had the bypass pipes with 4 oxygen sensors I decided that was probably the easiest to change and most likely to be the cause of the noise as the cats have 155,000km on them.

The good news is I didn't snap any of my existing catalytic converter bolts off while taking them out, but unfortunately the noise is still present with the cat bypass pipes installed.

So next will be to take the rear bumper and heatshields off and go for a drive. If it's still present then I guess the mufflers are the next target.