04 XC70 Has anyone else experienced this?

turbotim2 · Post by **turbotim2** » 02 Oct 2015, 05:57

Its not really a problem but over the last two years my car has been discharging the glass packing from the resonator out the tail pipe. I think last night it made its final discharge as a two huge hairballs were left in the road after a downshift going up a steep hill. It looked like I had run over two raccoons. The exhaust tone or volume has not changed a bit nor has any other aspect of the car. Although I may notice a slight increase in power, probably a 0.06% gain in hp at 6,000 rpm (this would be a significant improvement if we were talking about Hondas). Just curious if anyone else's has done this? I have never seen it happen before but apparently GM vehicles are known for it.

Post by **oragex** » 02 Oct 2015, 11:16

Maybe some rodent made his home inside the muffler?

turbotim2 · Post by **turbotim2** » 02 Oct 2015, 11:50

The material that has come out is the fiberglass packing from the resonator. Some people call it witches hair.

MarcM · Post by **MarcM** » 04 Oct 2015, 06:19

Back in the day, truck-necks found this desirable. One would buy a 'cherry bomb', saturate the "witch's hair" with gasoline and rev it until the cherry bomb gave up it's ghost. Loud but still had the regulatory muffler.
I'm thinking rodent nest in muffler... unless you've noticed a bark at certain RPM/power ranges. If the noise has increased as described, then it would be the resonator internal dampening. Automakers install resonators (basically a mini-muffler 'glasspack') to dampen 'undesirable' exhaust tones.

turbotim2 · Post by **turbotim2** » 04 Oct 2015, 07:50

It is definitely not a rodent nest. It is fiberglass, you can see right into the resonator with a light. There is no noticeable sound difference.