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how to plug holes drilled in cat

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DavePolyakov

Member
Joined
Aug 3, 2020
Location
Shoreline, WA
The previous owner drilled 4 holes in the catalytic converter. When idling you can really smell the unfiltered exhaust coming through the shifter hole. What should I use to try to plug it? Any advice is welcome, thanks in advance
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If you still have the stock exhaust I have a NIB 740/940 cat I'll sell you for $100. (Bosal Brand)
 
spock345 said:
Why would someone drill holes in the catalytic converter?
Click to expand...

Maybe it was plugged and they added holes to let the exhaust out? :lol:

Could also have been trying to beat smog. When my exhaust had a hole in it pre-cat I got some unbelievably good numbers at the smog station. It's been fixed since.
 
Now I'm also kinda worried it might actually be clogged. Why else would someone do this lol. I don't want to pay for it to get welded and then have it run like absolute crap and have to buy a new one. I don't hear any noises and plenty of exhaust still comes out the tailpipe. Is it probably in ok shape?
 
That isn't as bad as I thought. For some reason I pictured big half inch holes.

The easy answer is to weld it shut with a cheap harbor freight flux core machine. Then realize you can't seam seal and paint away the **** welds and then go buy another cat.

Also what is the temperature limit for JB weld?
 
If you are willing to disassemble that joint, run the largest bolt you can from inside out through each hole and then seriously crank down from the outside a nut with a washer made of softer material (Chinesium? Cheap exhaust gasket?) to help seal.

I would suggest this only if the metal screw approach (do add cheap gasket in between) does not work out for you and cat is not clogged with porn.

spock345 said:
Why would someone drill holes in the catalytic converter?
Click to expand...

Some people sniff paint. Others glue.
 
I've got an even easier way to find out if it's clogged and it will cover the holes. Buy some of the stainless steel metal tape from a good heating supply place. We have one in our area called Ferguson. Wrap the pipe with the tape to seal it up and find out if the cat is clogged. They do have the internal substrate fall apart or get filled with carbon. They can break loose internally and cause a lame exhaust rattle.
 
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