Julian
Hi guys,
My 850R wagon has had a rattle at low rpm which goes away as revs increase. It usually happens when the engine is under a bit of load, e.g.going uphill in a high gear. I always use 98 octane fuel so I don't suspect knocking.
I have tightened any heat shield I can find, including the long one running above the cat converter. I even added rubber washers between this and the body in case it was somehow rattling at that interface. I'm getting pretty sick of the sound, and got under the car today and hit everything I could see to try to track down the source of the noise.
When I hit the exhaust pipe, I can hear a similar sound to what I hear when driving coming from around the cat converter. The outer cover of the cat seems pretty tightly fixed, and its not hitting the heat shield above it. Is it possible that something inside the cat converter is loose and is causing the sound? Or does this not really happen?
Angus242164
It's fairly common actually, the matrix inside the cat comes loose and rattles inside the casing.
Occasionally the matrix starts to fall apart and can turn sideways and block the exhaust, or broken up pieces can be blown backwards into the mufflers and block them, not common but I have seen it.
deleted_user_160
+1 what angus said.
The mufflers can suffer the same fate if they are straight through perforated tube.
Ex850R
Try screwing self tapping screws into it to hold the matrix, do it till it stops rattling or de-cat it and do the sensor mod.
Angus242164
Or just get a new universal cat welded in, they're not too expensive any more.
