Hi All, 81 US 308 GTSi. I've always had a high pitch rattle sound (hi pitched almost like a belt squeal but not rhythmic, random). I had been assuming it was one of my aluminum header surrounds as they have all come loose. I finally got around to taking the diaper off as part of my rear bumper tuck (removing the spacers... MacCarbon kit going on the front). I found that one of the spring loaded exhaust bolts from cat to muffler was very loose and bouncing around. Thought that was it, but tightening that up only helped a little. Under the running car I can't really hear it and I certainly can't pinpoint it coming from any of the heat shielding/exhaust piping. From the rear of the car I noticed that it was louder on the right side so I did something I had never thought of before... I put my gloved hand over the right 2 exhaust tips blocking them off.... and the rattle stopped. Is this indicative of a loose baffle inside the (stock) muffler? Any other tests to try and pinpoint? Thanks! Jay
Check the small baffle right inside the tip. I had one come loose before and had to weld it back. I also had a baffle come loose inside the muffler. It was a rattle when I went over bumps. Cut the muffler open and re-welded it. Image Unavailable, Please Login Image Unavailable, Please Login
Yes it has cats. Under the car running I put a mechanics stethoscope on the cats (and muffler and in the tips...) and couldn't hear anything. With the car off I can bang on the muffler and cats with my fist and don't hear the familiar BB's or sand in a coffee can sound... Was really surprised it went quiet (and the exhaust doubled in intensity on the left side) when I blocked the right side with my hand. I had always assumed that the 2 sides were blocked off from each other.
OK, so I finally finished removing the spacers from the rear bumper. I can't be the only person who, when faced with an 1/8 of a turn on an open ender wrench at a time considered not doing the inside 2 nuts.... I persevered for what seemed like hours and its nice and tight. Started it up and I found that specifically it is the farthest right exhaust tip that the sound is coming from. If I cover the left 2 the rattle sound is louder out the right. If i cover the inside right tip you can hear the rattle louder. Covering the outside right exhaust tip either it stops the rattle or it just blocks the sound from the rattle.
Exhaust does not come out of each side equally. Its not divided up Left/Right. Sounds like something loose inside.
So today I thought... lets take the exhaust off and run for a bit just with the cats to see if the rattle sound is still there. 5 of the 6 spring bolts from muffler to cats came out easy. I can barely get hands in to the top one drivers side and cannot get a wrench on either side of that bolt. I was trying to avoid removing the cats as wll as I did not want to mess with air tubes and thermocouples as they look like they have not been disturbed for many years... Is that the only way to get this exhaust out with the cats attached or am I missing something? Thanks
I use angle wrenches and a socket with about a 10 inch extension to get them off. I never pull the cat if I have no need for it to be off.
I could not get to either side of that one spring bolt. I ended up taking the cat that is closest to the exhaust as it was easiest to get to the remaining bolts and with that one removed I was easily able to get the last muffler bolt off the other cat. Definitely sounds like a nut bouncing around in the muffler now that I have it off and maneuverable. Definitely did not come from the cats.
