Originally Posted By: mjoekingz28
Just got back from another mechanic who suggests its still the cat although I've had it checked. He said some stuff is loose in there and rattling and sometimes it will clog up, sometimes not.
I had a bad cat on a Volvo 240 that did exactly that. The core had broken and big chunks were rolling around inside. Sometimes it would block the exhaust flow, sometimes not.
When the car is cold, bang on the cat. If you hear anything rattling around inside, that is your problem.
My fix was to remove the cat, break up the core with a crowbar (it was pretty broken up already) and re-install the hollow shell. Drove it like that for a few weeks until I could get the new cat in.
