Cats plugged up?

[Trlrider]

Simple thing to do to eliminate the cats being the problem, loosen the exhaust at the manifolds and see if the issue goes away or is less."

Had a customer a few years back with the same issue. He threw several hundred dollars in parts at the truck including a starter, battery, tuneup, etc and did not fix it.
Brought it to us and the first thing I did was loosen the exhaust at the manifolds.
Truck would start, idle and go down the road without coughing.
Sadly, he had screwed with it to long and the backpressure from the bad cats caused damage to the cylinders and the engine was down like 50% or worse on compression.

This fuel we have today destroys the mid to late 90's VORTEC cats.

 

[White96k2500]

Simple thing to do to eliminate the cats being the problem, loosen the exhaust at the manifolds and see if the issue goes away or is less."

Had a customer a few years back with the same issue. He threw several hundred dollars in parts at the truck including a starter, battery, tuneup, etc and did not fix it.
Brought it to us and the first thing I did was loosen the exhaust at the manifolds.
Truck would start, idle and go down the road without coughing.
Sadly, he had screwed with it to long and the backpressure from the bad cats caused damage to the cylinders and the engine was down like 50% or worse on compression.

This fuel we have today destroys the mid to late 90's VORTEC cats.

I am probably going to cut them off today. Going to a shop to see about getting tailpipes ran in the next hour or so

 

[White96k2500]

I suspect they are bad. Exhaust still stinks after new battery, runs rough and it probably burns some oil which contributed to clogging them up and they have over 300k on them.

 

[White96k2500]

Forgot to mention I bought a new battery and changed to top post, it starts way better, definitely worth doing. Today i tried to make it to the exhaust shop and didn’t make it a mile down the road. The cats are so stopped up it was running even worse and started getting hot, i also felt the exhaust and before the cats is warm like normal. The cats were burning hot and the exhaust after the cats wasn’t even warmer than my arm so I’m cutting them off now.

 

[RawbDidIt]

Forgot to mention I bought a new battery and changed to top post, it starts way better, definitely worth doing. Today i tried to make it to the exhaust shop and didn’t make it a mile down the road. The cats are so stopped up it was running even worse and started getting hot, i also felt the exhaust and before the cats is warm like normal. The cats were burning hot and the exhaust after the cats wasn’t even warmer than my arm so I’m cutting them off now.

Did you try disconnecting them or removing the upstream O2 sensors before committing to removing them? Seems like the likely culprit, but still nice to confirm. You'll also want to go through everything and make sure they didn't get plugged up from other issues that will create more issues for you down the road.

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[White96k2500]

Did you try disconnecting them or removing the upstream O2 sensors before committing to removing them? Seems like the likely culprit, but still nice to confirm. You'll also want to go through everything and make sure they didn't get plugged up from other issues that will create more issues for you down the road.

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Honestly i just had enough of it and cut them off a few minutes ago. I’m pretty sure the reason for them getting plugged is burning oil + 314k miles. It’s on its third motor I believe ( second with me and PO said he swapped one in) and the last one burnt oil like crazy.

 

[White96k2500]

I realize that it probably wasn’t the best idea to just cut them off without double checking everything, but at this point whatever happens happens. I’m gonna get the exhaust done this week hopefully, maybe next and hopefully all is well.

i did notice though when I started it after i cut them off it still smoked some. Im not sure if it’s just smoking because it’s cut off or what. I didn’t really think 63 degrees would as cold enough to make it smoke but well see what happens.

 

[RawbDidIt]

I realize that it probably wasn’t the best idea to just cut them off without double checking everything, but at this point whatever happens happens. I’m gonna get the exhaust done this week hopefully, maybe next and hopefully all is well.

i did notice though when I started it after i cut them off it still smoked some. Im not sure if it’s just smoking because it’s cut off or what. I didn’t really think 63 degrees would as cold enough to make it smoke but well see what happens.

Was it smoking, or was there just carbon dust pouring out? They look pretty similar if the dust is fine enough. Also, your cutting would produce heat high enough to smoke oil, depending on how you cut it. Take a look at your cats now that they're out, take a picture if possible, bonus points if you have a flashlight trying to shine through from the other side.

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[White96k2500]

Was it smoking, or was there just carbon dust pouring out? They look pretty similar if the dust is fine enough. Also, your cutting would produce heat high enough to smoke oil, depending on how you cut it. Take a look at your cats now that they're out, take a picture if possible, bonus points if you have a flashlight trying to shine through from the other side.

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It looked like white smoke, it was also dark outside so it may have just been dust (i hope). I cut it with a sawzall so that may be possible too. The cats are actually still sitting on top of all the crossmembers, im gonna have to cut them behind the exhaust flange because the bolts wouldn’t break lose. I work tomorrow and Thursday, so friday i should have them out and be able to take pictures.

 

[White96k2500]

Was it smoking, or was there just carbon dust pouring out? They look pretty similar if the dust is fine enough. Also, your cutting would produce heat high enough to smoke oil, depending on how you cut it. Take a look at your cats now that they're out, take a picture if possible, bonus points if you have a flashlight trying to shine through from the other side.

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I crawled under and took a picture of the inside of one of them.

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This is the best picture i have right now. I’m not really sure what a new one is supposed to look like. So what do you think?

also i got a quote from the exhaust shop for $450-$500. How does that sound? I’ve never had exhaust done on anything before.