Exhaust observations and question.
Thread Starter
Le Mans Master
Joined: Sep 2014
Posts: 5,278
Likes: 539
From: Kelowna BC
Exhaust observations and question.
Left to right.
-Factory pipes are steel (assuming aluminized), magnet grabs on. Pretty darn good condition for 50K miles and 10 years I'd say.
-See darkening on DS cat? Interesting that I was getting P0420 (DS cat flow warning) message regularly before I pulled the car for winter. Anybody know if this darkening is a sign of a failing cat?? Before I drive it I'll swap rear sensors first, just thought I'd see if this means anything to anybody though so I might have a better idea before spring (seems so far away).
-Cats are steel.
-Here's where it gets interesting. I see where a poster a while back asked if the factory pipes are 2 1/2 or 2 3/4, as the area 3" after the manifold connection are actually more like 2 3/4", and they are ugly (why?), AND they are not magnetic! Anybody know what material this portion is, and why it's larger and ugly? It necks up to this after the manifold and then back down to 2 1/2" at the cats. Stainless? If so, it sure seems rusty. And if so, why SS just for this run?
-Factory pipes are steel (assuming aluminized), magnet grabs on. Pretty darn good condition for 50K miles and 10 years I'd say.
-See darkening on DS cat? Interesting that I was getting P0420 (DS cat flow warning) message regularly before I pulled the car for winter. Anybody know if this darkening is a sign of a failing cat?? Before I drive it I'll swap rear sensors first, just thought I'd see if this means anything to anybody though so I might have a better idea before spring (seems so far away).
-Cats are steel.
-Here's where it gets interesting. I see where a poster a while back asked if the factory pipes are 2 1/2 or 2 3/4, as the area 3" after the manifold connection are actually more like 2 3/4", and they are ugly (why?), AND they are not magnetic! Anybody know what material this portion is, and why it's larger and ugly? It necks up to this after the manifold and then back down to 2 1/2" at the cats. Stainless? If so, it sure seems rusty. And if so, why SS just for this run?
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
LOL!! GM has a 80K Power train warranty. That includes the CAT. The pipes from the manifolds to the end of the CAT outlets is stainless steel. Its a low quality stainless but, its stainless. It has to last the full warranty period. GM DOES NOT, mandrel bend its exhaust tubing so, you get all the dimpling and crazy sizes. GM also sizes the exhaust manifold outlet to meet minimum emissions standards. Most C5 have a PUP CAT directly after the manifold. Pretty much, 2.25 ID is all the diameter that you get if you look at the complete system.
If you want to know if the CATs are working,, read the CAT body temp at full operating temp with an inferred laser thermometer and see if its 150-200 degs higher than the manifold outlet temp. If not,,, its dead.
Hit the CAT with a rubber mallet and see if it rattles inside. If it does. its bad. If you mufflers rattle, the CAT Ceramic Matrix is most likely melted and inside the mufflers.
Get some stainless LT Headers and a complete cat back system and be done with it!!
BC
If you want to know if the CATs are working,, read the CAT body temp at full operating temp with an inferred laser thermometer and see if its 150-200 degs higher than the manifold outlet temp. If not,,, its dead.
Hit the CAT with a rubber mallet and see if it rattles inside. If it does. its bad. If you mufflers rattle, the CAT Ceramic Matrix is most likely melted and inside the mufflers.
Get some stainless LT Headers and a complete cat back system and be done with it!!
BC
Thread Starter
Le Mans Master
Joined: Sep 2014
Posts: 5,278
Likes: 539
From: Kelowna BC
Thanks much Bill.
I rapped both cats with a rubber mallet last night, no rattling. Will try the mufflers tonight when I get home, forgot about that possibility. Hoping there's no issues with my Ti mufflers though, I am more than happy with them. There's an expense I don't want for my Z.
Headers are absolutely on the horizon this winter while up on stands, either DIY Tri-Y's or one of the more cost-effective LT's.
As for the warranty, I wonder how that works across the border (mine was originally a US car). Regardless, I guess I'll just get them out of there and either run cat-less or get new aftermarket units when putting the headers in.
I rapped both cats with a rubber mallet last night, no rattling. Will try the mufflers tonight when I get home, forgot about that possibility. Hoping there's no issues with my Ti mufflers though, I am more than happy with them. There's an expense I don't want for my Z.
Headers are absolutely on the horizon this winter while up on stands, either DIY Tri-Y's or one of the more cost-effective LT's.
As for the warranty, I wonder how that works across the border (mine was originally a US car). Regardless, I guess I'll just get them out of there and either run cat-less or get new aftermarket units when putting the headers in.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Call GM Customer Assistance ( the number is in the owners manual and or on the INTERNET) and ask about your power train warranty.
The GM warranty should be the same regardless where your at.
NOTE,, The car will have to be diagnosed at the dealership to determine if there bad or not. You best do your own troubleshooting to prove there bad before you take it there AND make sure that the car is running properly (NO DIAGNOSTIC CODES) or they will blame IT on owner negligence.
If it were me and I knew that they were BAD and I had a warranty, I would get it replaced. Brand new CAT pipes are worth some cash or handy if you ever have to convert back for what ever reason..
If they really are bad, it shouldn't cost you anything if you are still under the power train warranty.
Bill
The GM warranty should be the same regardless where your at.
NOTE,, The car will have to be diagnosed at the dealership to determine if there bad or not. You best do your own troubleshooting to prove there bad before you take it there AND make sure that the car is running properly (NO DIAGNOSTIC CODES) or they will blame IT on owner negligence.
If it were me and I knew that they were BAD and I had a warranty, I would get it replaced. Brand new CAT pipes are worth some cash or handy if you ever have to convert back for what ever reason..
If they really are bad, it shouldn't cost you anything if you are still under the power train warranty.
Bill
Drifting
Joined: Sep 2009
Posts: 1,719
Likes: 4
From: cinnaminson n.j.
St. Jude Donor '14
No offense Bill, but chevy did not have a 8/80 power train warranty in 2004. I think your are referring ti the 8/80 federal emission warranty that does cover the cats. The OP's car is 11 model years old. He's out of coverage.
I agree with installing lt's with high flow cats and tuning out the codes. New factory cats if you can find them are $2600.00. You can't buy used at a salvage yard because they are illegal to sell used. The only way to get them would be for someone to sell you a used Hpipe.
I agree with installing lt's with high flow cats and tuning out the codes. New factory cats if you can find them are $2600.00. You can't buy used at a salvage yard because they are illegal to sell used. The only way to get them would be for someone to sell you a used Hpipe.
Thread Starter
Le Mans Master
Joined: Sep 2014
Posts: 5,278
Likes: 539
From: Kelowna BC
Winter project
I was planning to do headers either way, x-pipe, and likely cats if they proved to be bad. Now I have plenty to do before spring. Fun (hopefully a mild winter as predicted) times ahead.
Thanks guys.
P.S. No rattle from anywhere in the exhaust system. Ti's are OK, phew.
Thanks guys.
P.S. No rattle from anywhere in the exhaust system. Ti's are OK, phew.
Last edited by grantv; Dec 9, 2014 at 09:57 AM.
Burning Brakes
Joined: Dec 2003
Posts: 1,243
Likes: 5
From: Loveland CO
the H-pipes are stainless, the front portion is most likely a double wall (head insulation inside between the 2 layers to keep heat down). the hot spot on the back might be from a rich fuel mixture on that one side.. might indicate time for a tune up or a new primary O2 sensor.. might pull the plugs and "Read" the plugs and see if they are black (rich), white (lean) or clean (perfect). there are different grades of Stainless, OE does NOT usually use T304 (non magnetic, doesnt rust).. they usually use T409 (has surface "rust" that actually seals and protects the pipes from rusting threw). OD of the Hpipe should be 2.5", the front part being double wall is going to measure thicker but should still have the same ID..
S
S
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Thread Starter
Le Mans Master
Joined: Sep 2014
Posts: 5,278
Likes: 539
From: Kelowna BC
Will do for sure on the plugs when I pull the manifolds and put in headers. I'll also get a mail order tune after all is said and done, so new plugs and all should be a clean slate for spring.
And makes sense on the thicker/double wall pipe to keep heat down. Perhaps it also gets the cats hot quicker, helping emissions... (?). Not necessarily a question, just thinking aloud.
Thanks.
And makes sense on the thicker/double wall pipe to keep heat down. Perhaps it also gets the cats hot quicker, helping emissions... (?). Not necessarily a question, just thinking aloud.
Thanks.