Blowing through cats every 8-10k mi?

[ghost5.3]

This happened to the previous owner twice. When I purchased the truck (right after the second engine blew) i replaced the engine. I inspected the catalytic converters and realized that they were hollowed out. I then put the cheapest cats money could buy on the truck. They blew out within a week and left me on the side of the road. I then paid up and got some good AP cats. Just recently I started getting my 420s & 430s again. I get a whistle that comes from the exhaust and i assume its just because there isn't a clear passageway. My pressure also builds up on high acceleration. Does anyone have an answer to why my truck burns through these things like nothing? cant be the engine because this is the 3rd engine that has blown them out.

[CamGTP]

Anything that isn't from GM or those high dollar Magnaflow cats just don't last.

[richard wysong]

Cats don't die on their own, they are murdered by the way the engine runs. 

[ghost5.3]

14 hours ago, CamGTP said:

Anything that isn't from GM or those high dollar Magnaflow cats just don't last.

Thats what I figured, but AP is a high dollar cat. I mean we are talking about $1500 for the part alone. Doesn’t make sense that it would just blow out after 4-5 months

[ghost5.3]

10 hours ago, richard wysong said:

Cats don't die on their own, they are murdered by the way the engine runs. 

Also something I had a general idea of, but I can’t comprehend how 3 different engines have all blown out cats. Am I being too hard on the truck? I mean for the most part I don’t even get over 3k rpm. It just doesn’t make sense 

[richard wysong]

It is not the engine itself but the sensors that control the fuel mixture. Are you swapping complete engines or just long blocks and using the original manifolds, sensors and accessories? Sounds like you may be running too rich causing the substrate to melt down

[diyer2]

I have never replaced a cat. Figure it out or buy cats.

[silveradosid]

3 engines same think, check air intake for a Crack and letting in air. Are o2 sensors reading correctly and last check the rest of the exhaust system, if the truck sat for awhile maybe something has made a nest in the muffler 

[dna9656]

DO NOT BUY AP CATS. I bought AP cats for my 2015 Silverado. The Flange on the end of the Y pipe was made too small, it would not hook up. I bought them at WWW.PARTSGEEK.COM. Parts geek will not pay return shipping for any reason not their fault. If I wanted my $550.odd back I have to pay the $121.odd shipping. I did and because AP copped to the defect I got my money back, AP ignores my emails asking them to refund the shipping I paid to return their defective product. Don't buy from AP Exhaust. 

I bought the GM cat Y pipe, it installed way easier than the AP POS and through this forum I was given the break-in instructions from GM; AP EXHAUST provides NO break in instructions.  I have had no codes since I installed the GM cats.

I emailed AP EXH. again today, I got a auto reply, we'll see what happens.

 

Edited September 7, 2024 by dna9656

[dna9656]

HI RICHARD!

                     My 20 15 Silverado is a insurance total rebuild. I hear GM disavows the VINs (and therefor the truck) of totals that are returned to service. I read about some recalls on 2015 trucks, air bags and the brake module needs to be reflashed for  the brakes going to non powered status. I run my VIN on the Gov't recall web site and get no hits. Can you run my VIN and see if I'm included? I suppose if me truck is affected I'd have to pay the dealer for the reflash, what about the air bag? TIA for any help you can afford me.

3GCUKSEC2FG305725

[mjm-1957]

According to the VIS,  the truck does not have any warranty block or salvage title as far as GM knows. All campaigns are completed and listed as closed. Truck was sold new in Canada.

[dna9656]

Thanks mjm-1957!!!!! What  is a "VIS"?