How to determine if CAT is clogged

[Todd Richmond]

Before taking my Viper to the shop to determine why it is down 80+ HP, it was suggested that I check the cats. How do I determine if they are clogged and can I get a gross idea w/o having to find an exhaust pressure gauge?

I took off the driver side cat and can't find the brand that the previous owner installed - it isn't stock. It is much smaller, lighter than the stock cats and its honeycomb looks to be in perfect shape. I can also see a little light through the opposite end, but it is quite dim.

Thanks and feel free to let me know if this is a waste of time before I unbolt the other side

 

[Miles B]

Have you checked your plugs and wires?

 

[99 R/T 10]

Ditch the cats, go without.

 

[BigCarrot]

When cats are clogged, they tend to roll around and meow alot. You may also notice some irritability and or lathargy. A little fiber or grass should do the trick. Hope that helps.

 

[Tom F&L GoR]

Early pellet type cats would melt the pellets together and truly clog the exhuast system. Newer monolith cats usually don't, because while excess heat or metallic additives may kill the catalytic function, the ceramic structure survives. The honeycomb structure would have to break (could if the padding holding it in place loosens) and you hear it rattle; the odds of melting it without melting your paint are pretty low. The small amount of light might just be because you're looking through thousands of little straws and you have to look directly at the light source to see anything. Let us know what happens.

 

[HP]

A vacuum dial gauge plugged into the intake will tell you if your exhaust
is restricted. You can pick one up for around $19 at any auto parts store.
Instructions are included, so you don't have to be familiar with using one.

 

[96 GTS]

Ditch the cats, go without.

I agree. The BEST way to check for clogged cats is to remove them from your car, then rip them open and check to see what you can find.

 

[GR8_ASP]

Just looked under my bench and my cats are still clean. No squirrel nest or other debris. Maybe it should be as easy to check yours.

 

[David Jenkins]

check the back pressure at the front O2 sensor holes.dj

 

[Todd Richmond]

I was going to check the backpressure at the o2 holes, but I went to Speed Merchant (the only knowledgeable part store I've found so far) and they didn't have anything that would mount - I was told by a mechanic that I need to check while under driving load and it should be < 3 psi