2008 Expo Catalytic Converter

[Gary Hayre]

Everyone,
Had a rattle coming from under engine. Used doctor scope to narrow the noise to driver side cat. Bought replaced cat from Rock Auto (Davico Brand)...economy one...The OEM cat is listed at 1400.00 compared with 250.00 from Rock Auto.
Installed no problem, rattle gone.
However, a deep rumbling noise comes when accelerating. Sounds like broken exhaust pipe, but there are no exhaust leaks, and pipe clamps are solid with plenty of overlap on the exhaust pipes.
Could it be just a cheap cat with higher flow rate?
Anyone else have this issue?
Any solutions, aside from saving for months to get the OEM cat?

 

[Trainmaster]

Gary, not positive it's your problem but I've had nothing but headache from aftermarket exhaust parts these days. They're noisy and just don't last. I've depended on Walker and now they've been rotting out in 18 months. Wish I had a solution for you other than the $1400 one. Just make darn sure there's not a leak somewhere. They're easy to miss since looking and listening for them is such a pain.

 

[Gary Hayre]

Thanks for your reply, question: did the Walker brand make it louder?
PS: because I'm in Canada, the actual price on OEM cat is $2487.00.......LOL

 

[Plati]

Can you junkyard pick a Cat?

Did you diagnose the bad Cat (before removing) by using an infrared gun or other method?
Did you post mortem the Cat and identify a failure?

 

[Gary Hayre]

Junkyard cats are hard to come by.

The original cat has a broken piece of honeycomb inside, you can see it moving through the O2 hole.

 

[Gary Hayre]

Solved.
There was no actual problem with the aftermarket cat. I went to a muffler shop and they found the flange seal was leaking, so they sealed it, all the noise went away.