Chevy & GMC Vans

What does a catalytic converter where the insides have come loose sound like???

I've got a loud marbles in a coffee can sound comming from what appears to be the pass side mid van. There for a few seconds when I start the van and then for a sec whenever I get on the throttle and when I hit a large bump also sometimes when stopping. I've also noticed the van becoming lethargic and yesterday it threw a P0300 ( unspecified miss if I'm not mistaken)
Does this sound like it could be the cat crapping out and the guts coming loose??

that's pretty much what a disintigrated cat sounds like. Get under the van and rap on the cat with your fist, or a rubber mallet (when it's cool obviously) If you get the marbles in a can sound, the honeycomb inside has broken apart.
the code I don't know about. My manual shows P0300 engine misfire, but I don't know if it's the cat causing it. A broken up cat will back up the exhaust and make it sluggish (or worse).

Just as Kings said hit it with your fist, if it rattles > its toast. Plus if it is the original cat change it at 100k for a Free-er flowing performance cat. Do Not use the Catco brand, they are cheap low quality restrictive crap, that will only last for one smog check, you will have to replace it again for next time.

SoCalli V8 wrote:Just as Kings said hit it with your fist, if it rattles > its toast. Plus if it is the original cat change it at 100k for a Free-er flowing performance cat. Do Not use the Catco brand, they are cheap low quality restrictive crap, that will only last for one smog check, you will have to replace it again for next time.

Idea's for a replacement cat??.Ballpark on costs??.

Some converters have pellets coated with Platinum, palladium and rhodium. So pounding on one of these will rattle anyway.

I recommend fitting a 3 inch in and out Magnaflow Hi Flow cat normally fitted to a 454 motor.

I have this size cat on my 2.3 turbo 4 cyl Merkur XR4TI daily performance driver and on my V8 Astro also.

Both have custom mandrel bend exhaust systems.

Try another shop. Those guys are trying to hose you. I had my cat replaced with a hi-flow cat, flowmaster 40 and 2 1/2" pipe from the cat all the way back. Midas, coincidentally, did for me for about $320 plus tax.

Who ever you choose.... just ask them are you gonna weld in manderal bends? OR > "Crunch-Bend" my Exhaust system? ....

If they answer we are gonna bend-up your exhaust system, then > WALK AWAY....!

You wanna have "manderal bends" that are welded in, for a performance upgrade.

I replaced my cat for that reason. Inside came loose and it rattled. I welded it in myself. Cost: $140.00.

Okay I ended up welding the catback all together and routing it out the new rear bumper myself. My question is what is the best way to install the Magnaflow Cat if I do it myself. My problem is the AWD and the torsion bar that seems to be right in the middle of the cat. Would it be best to unbolt the Y-Pipe and cut it out and weld in this puppy? I just didn't know if it was possible to take the y-pipe out with the torsion bar in place and I don't want to find out the hard way. Any help much appreciated guys.

I just got a Magnaflow cat welded in last week at a local muffler shop. With the Magnaflow cat included and installed $150 out the door. But then you gotta keep in mind that the shops get $80 for the old cat, Around here they do atleast.