cat rattle

[david944]

Well, it rattled then it quit, and now my cat has started to rattle and make a lot of noise. Let me tell you what it's doing. When your driving you don't notice it but, at idle and when the car is shut off i can climb under it and hit the cat and it will rattle. It's like the stuff inside the cat has come apart or something. Should I just gut it?? Or try to fix it??

[david944]

Thanks Shaun, I'll have to check that out, though I not exactly sure that the shield is the problem.

[p0r2chby]

I have an idea. I think it may be related to your Oxygen sensor.

Our car had experienced a rattle just at the feet of the passenger area. Sometimes it would move a bit further back.
It was really strong on start up and at idle, I could just hear it. We also looking at the CAT heat shield and found it clear
of any contact points for vibration.

I then thought that it might be a piece of something that was caught in the header pipe area in front of the CAT.
My smog test point tube weld had come free so a cap had been put over the hole and it was possible that
something had fallen inside.

After all that checked out, I removed the Oxygen sensor and found that the hat had come off. By hat, I mean the end of
the sensor that hangs out into the exhaust stream. The sensor still worked but the broken off hat part was now in my pipes.

The car was at 103K miles and I think it may have been the original sensor as I had not changed it and had no history
papers related to it. After a new sensor, some exhaust gaskets and misc. parts, hangers etc. that rattle is gone.

[david944]

thanks, it didn't even think about the sensors. It could be that. I haven't had a whole lot of time to mess with it, so this weekend i'll try to figure whats wrong.

thanks,dave