If you hear rattling sounds under your car while it is running is it the catalytic converter and if so how much will this cost to repair?

Answer 1

It is probably the heat shield that is between the converter and the bottom of the car. It does what the name. They can be a pain to fix properly. I have always tried fixing mine but the "rattling" noise would always return sooner or later. I ended up taking mine off. Plus these heat shields get old and tend to vibrate relentlessly. Best best is to have someone you know take a look and see what they can do.

Yes it is, and it can cost anywere from $80.00 to $200.00 to fix.

It is also possible that the ceramic compount "honeycomb" in the catalytic converter is breaking apart and/or broke loose inside the converter. If this is the case, you *might* fail emissions but it shouldn't hurt anything (other than failing emissions).

http://www.autozone.com/servlet/UiBroker?UseCase=S001&UserAction=viewSimpleDiagInfo&Parameters=info

just buy a clamp for your heatsheild.. its the cheapest and easiest fix.

I fixed my heatshield with a screw gun and some self tapping screws . The shield is spotwelded in place. Find the areas that have came loose and screw, I used 3/8 inch panheads that where galvinized, they hold up to the heat very well and I hav'nt had anymore problems. I did this 2yrs ago and have had no problems.

Answer 2

Unfortunately, it is virtually impossible to diagnose a problem with such little information. You didn't even include the year, make, or model, of vehicle.

For example, many years ago, I was at a mechanic's garage, when a woman drove up to us, and comlained that, after he fixed her car, the radio no longer worked. The mechanic was insistent that nothing he did could have affected the radio. But, he did, if only inadvertently, when I pointed out that the door-mounted antenna was pushed in. As soon as I pulled it out, the radio was fine; he had pushed it in to avoid damaging it during service, and had forgotten about it. We all laughed about it, though I'm sure the woman was a little PO'd, if not embarrassed, at having had to return for such a minor issue.

Unfortunately, rattling can be due to anything. Another time, I drove off from an oil change, when, less than a mile away, I heard a rattling from somewhere, but, couldn't figure it out (I'm a backyard mechanic with over 40 years of experience with multiple years, makes, and models). Then, I remembered that he said he had removed the wheels to check the brakes (totally unnecessary). When I removed the first hubcap, a socket from a wrench set fell out!

If you can't or don't want to go under your hood or car to investigate - - safely, of course - - then take your vehicle to a trusted general mechanic, not a specialty garage, who will either not find anything or find something, but demand that you replace the entire system. If your vehicle is less than 5 years old and has had no major damage/accidents/repairs in that time, not fixed by the dealership, then take it to the dealership, as it may be something that's still under warranty.

And, next time, please give more information, especially the vehicle specifics, including submodels and any appropriate, corresponding, options, such as the number of cylinders, etc.