My '89 Civic has about 250k miles. I suspected the cat may be bad, so I took it off & visually inspected it.

I can see light through it, but I can't see perfectly clearly through it. It is like there is only somewhat clear light through the middle portion, but not around the edges.

How do I know if it is restricting flow?

Thanks.

 

Put pipe in it and gut it

 

if its bad ill give you 30 bucks for it

 

Gonna need a hammer too :D

 

You will never be able to see light through it due to the nature of how a cat is built. Sounds to me like its not clogged though since you can see light through it in the center. A Cat is built with a honey comb of precious metals on the inside. Because of the shape, you can only see straight though. If there is any angle at all, the light will be blocked. Thus you can only see through the center.

Here at Honda, we test CAT's by temperature. If it is over 1000 deg Celsius, its Bad, but considering you cant do that, its a little more difficult to diagnose. But if its bad, it will get ridiculously hot and start to turn color.

 

Thanks all. Based on your information, Splatranger, it appears that it is not bad.
A couple of questions;

- Do cats have a life span and go bad eventually even from normal use?

- How much is a used cat like this worth to someone to sell or recycle?

- I've been considering a test pipe. What are your thoughts?

 

Yes they do have a lifespan and will go bad, however it is entirely dependent on how the car is driven, how well it is maintained (how well the engine runs, A/F ratio etc..), what type of fuel is used...etc... A cat, in this day and age, is meant to last forever. (a complete life cycle of a car) but there are plenty of cats that will last 1/2 a million miles if they were treated well.

Usually you can get 50 bucks or so at a recycling center dependent on how much precious metal is left, but you could be as low as $20. They will put a stick in it to see how far the metal has worn away and base it off that.

Test pipes are no big deal, but you will have more exhaust. By that I mean fumes, and there will actually appear to be more smoke coming out. If youre environmentally minded, dont do it. If you live in a rural area, it doesnt matter.... I have a test pipe on mine, but my car didnt come with a cat. If it did, I would keep it on. It helps alot with rasp.