H3T Alpha exhaust advice

[Elmers04]

Dealership says my cats are bad and want 4400$ to replace them. I’m looking for an alternative, does anyone make a direct fit exhaust kit?

 

[alrock]

All of the cats are bad? What symptoms are you having that got them to this diagnosis? I can't recall how many cats the Alphas have. Is it 2, 3, or 4?

 

[Elmers04]

Check engine light, dealership ran the codes and said bank 1 and 2 failure. Said it’s the cats. Before I spend that much I want to make sure it’s not the O2 sensor or something. If they are bad I’d rather run a true dual exhaust and delete the cats

 

[alrock]

Did you get the specific codes? You might be able to get away with a cheater/spacer in the downdraft O2 sensor that pulls it out of the exhaust stream. I'd start there, unless the codes you received conclusively indicate the cats. (Note that I said the codes, not the dealer! ) You might have a great dealer, maybe not, but am glad you're doing your homework.

 

[Happy Hummer]

OK I'll bite!
I'm sitting in my office in USA WI. I cant see your H3 and I cant drive it.
That is probably unlikely.
Run to your local vato zone or the equivalent and have them run the diagnostics so you can then provide your H3 stats and the codes so we don't have to play the guessing game.

 

[Happy Hummer]

Because that would mean you have at least two cats that died at the exact same time and day, week, month. You get the picture. Then if there are any other down stream cats they to would have to go bad too.

 

[Jeepwalker]

You might be able to get away with a cheater/spacer in the downdraft O2 sensor that pulls it out of the exhaust stream.

The replacement price seems insanely high. Where did they come up with that? If that turns out to be the case, you could do as suggested above. Check ebay, there are lot of these spacers. You need to get one with the right thread. It's basically a spacer (adapter) you screw in the pipe between the sensor and the pipe. It 'tricks' the ECM into thinking the cats are working 'right'. A few bucks a piece.

BUT, is your truck going through any coolant or oil? If you had a leaking head gasket (or head), the leaking anti-freeze may have knocked out the cats. Not saying that's the case, but it's one thing that could do it. It's worth checking into so you don't put on new ones and they fail as well.

A few other options you have are: 1) Cut them out and instert regular pipe in their place. 2) Buy a new Y-pipe with new catalytic converters. 3) Cut the old converters off and find some aftermarket converters that'll fit and re-weld them in place. But first determine for SURE your catalytic converters are bad in the first place.

 

[aspen]

bank 1 and bank 2 are o2 sensors been there done that . but i would double check anyway there a lot cheaper then 4400

 

[720H]

Thats good advice go to auto zone and have them run a free check for second opinion. Or you can get a decent scanner 20-50 bucks yourself and check whenever you want. Can reset the light on things if not real serious. Thats a pretty steep price cant have the dealership do cat work unless its under warrenty. Its probly about 1500 at a shop. Cant just pipe around the cats have to tell the computer everythings Ok or your fuel trim will be off

 

[rascole]

Coolant is kryptonite for cats. Just a small amount will kill them. But it is usually just one side, cheap

 

[Exodus]

as far as i can remember the I5 only has the one cat,which is part of the header\exhaust

dont know what the alphv-8 has

 

[Doc Olds]

Alphas have 4 cats. One Pup Cat on each side just after the exhaust manifold flange, and a second small Cat just before the Exhaust Y Pipe connections on each side. Only the Pup Cats in front are monitored by O2 Sensors. The price reflects that the H3T exhaust is discontinued and whatever stock is out there is gold.

 

[DirtyDirt]

I have an 09 Championship Edition. It has the 5.3 in it, with 4 cats total. I have a low RPM rattle that sounds like a heat shield vibration type of sound. Went to the local muffler man to see what was going on. They quoted me $4000, said that the passenger side rear cat was bad, and they are all the factory installed units. The guy said that they all needed to be replaced, because they are more than 10 yrs old. I want to eliminate the cats al together if possible. Is that possible without codes and the computer messing fuel trim up??

 

[Doc Olds]

Only the front Pup Cats are monitored. What you do behind that doesn't matter. If you mess the the front set, you will have CEL issues and need to find somebody that can tune around the situation with HP Tuners, etc... Keep in mind, any licensed repair facility caught removing or deleting emission controls face heavy fines and license action.

If you can cut out the rear cats and weld in a straight pipe replacement yourself, you solved your existing bad rear cat problem. Good luck.