Any idea how to tell if the catalytic converter on my '81 is bad? The rest of the exhaust from that point to the muffler was replaced because it was rusted out. I fixed a minor leak in the CAT but didn't want to replace it. I also cleaned it out (youtube'd a few techniques) but just want to ensure it's not causing any flow issues. Is there a way to check this?

I don't have a test pipe but if the CAT is bad I may get one from AR and replace.

Usually they get plugged up. You'd notice an abnormal lowered performance. I've never seen it on a Spider but I've had a car where the exhaust manifold glowed red at night. That couldn't do no favors for the valves.

Or just buy a new one. I got this one for $160 on ebay.
http://www.ebay.com/itm/121293580490?_t ... EBIDX%3AIT
Kirk

use an infrared temp gun to check the inlet and outlet temperatures. A good working cat will be 100 degrees hotter at the outlet

klweimer wrote:Or just buy a new one. I got this one for $160 on ebay.
http://www.ebay.com/itm/121293580490?_t ... EBIDX%3AIT
Kirk

That looks really slick. Thanks for the link.

So Cal Mark wrote:use an infrared temp gun to check the inlet and outlet temperatures. A good working cat will be 100 degrees hotter at the outlet

In Canada those cost about $99. Maybe I'll see if I can borrow one.

less than $30 at Harbor Freight

30 bucks works for me, they are having a big Memorial Day Weekend sale too.

rjkoop wrote:

So Cal Mark wrote:use an infrared temp gun to check the inlet and outlet temperatures. A good working cat will be 100 degrees hotter at the outlet

In Canada those cost about $99. Maybe I'll see if I can borrow one.

I got one for about $30 at Canadian Tire.

$0.00 if you just remove it as it is not required for emissions testing etc

$19.99 at Princess Auto

http://www.princessauto.com/en/detail/i ... -p8496622e

4uall wrote:$0.00 if you just remove it as it is not required for emissions testing etc

$19.99 at Princess Auto

http://www.princessauto.com/en/detail/i ... -p8496622e

Out of stock item at this time.

this is http://www.princessauto.com/en/detail/c ... -p8568750e

4uall wrote:this is http://www.princessauto.com/en/detail/c ... -p8568750e

Range is a little low on that one for checking a cat since fully lit they can be over 500 degrees F to a max of 1,200 F before they are considered overheated while that thermometer maxes out at 485 F.

Here is what Walker Exhaust has in its Converter FAQ:

" Keep in mind that the converter's rear weld ring temperature is directly related to the amount of work the converter is performing. Therefore, elevated temperatures may indicate an emissions issue.
If the rear weld ring is significantly cooler than the front, the converter may not be lighting off. This may indicate the converter has failed, or that the exhaust mixture is not correct - the symptom of an underlying emissions issue.
Typically, converter temperatures will not exceed 1200º F on a properly running engine. Periodic operation above 1600º F can negatively affect the precious metals coating on the substrate, reducing its efficiency. Excessive temperatures can reduce the converter's durability, or - if high enough - destroy the converter's matting or substrate.
Damaged matting and melted substrates typically occur at temperatures exceeding 1700º F. It is possible to test for a cracked substrate or damaged matting by tapping on the converter housing. Using a rubber mallet, "thump" the shell, listening for loose components.
A bronze / blue rainbow discoloration of the shell typically indicates elevated temperatures. If the converter is removed, look through the substrate to observe whether the small passageways are melted or collapsed. The substrate may actually appear normal at either end, since the substrate melts internally."

4uall wrote:$0.00 if you just remove it as it is not required for emissions testing etc

$19.99 at Princess Auto

http://www.princessauto.com/en/detail/i ... -p8496622e

Yep. Just a little worried and not going stock and the exhaust noise being too loud. Although right now there is a minor leak at the catalytic converter (I fixed with muffler repair goo but it's starting to go again) and it's already a little noisy. Just trying to decide between a new CAT or the test pipe. I like the 'bolt in' type exhaust and would rather not get a muffler shop to weld in a new pipe. I like the idea that I can remove the exhaust myself.

Once again with what I've learned on this Fiat I was able to get the confidence to replace the exhaust on the kids beater 2008 Sentra (1/4 million kms!) myself for $300 when the muffler shop wanted to charge $1000+. Used bolt in exhaust components.

That's excelllent! It is a great feeling when you can fix something yourself! I went with the test pipe, muffler and Ansa in the rear was already there on my carbed '77 and it's really not loud at all.