S14 pre-cat gone bad. What's a good/cost-effective way to replace it?

[beefcake6681]

So my S14's pre-cat has a bad exhaust leak and I'm assuming its gone bad. Anyone here replaced the pre-cat? Do you just cut it off and weld on a new cat?

[idlafie]

If it's the round-sized cat directly below your exhaust manifold, you should have an exhaust shop unbolt it, cut the flanges off, weld the flanges to the NEW cat and then bolt it back onto the exhaust manifold. Either that, or locate another intact working catalytic converter from another S14 and replace it yourself. You can find those either here on Zilvia from someone parting out their S14 or at your local junkyard / engine rebuilder shop / muffler repair shop.

The catalytic converters directly below the exhaust manifold usually go bad when the honeycomb inside separates from the metal inside the cat OR the honeycomb inside the cat melts from too much fuel being dumped into the exhaust, (Don't ask me how, but I melted the honeycomb inside a cat once...if I can find the pictures, I'll post them so you guys can see).

Anyhow, it's better if you have your cat / exhaust bolt-on instead of cutting it off & welding it back on. If you ever have to service the motor in the future, being able to unbolt the exhaust pieces off in sections is a hell of a lot better than dealing with one long piece of exhaust cuz it's been welded. It may be more expensive but it's worth it if you plan on keeping the car for a long period of time and servicing it yourself.

If it's the resonator...then you'll have to have the muffler shop cut it off & weld in a replacement. If it's the muffler, those unbolt. Just find a suitable aftermarket exhaust & bolt it in.

Anyhow, hope this helps...

ID

[beefcake6681]

Thank you for your response. It is the roundish bulge below the exhaust manifold. I've been going through parting out threads and haven't found anyone selling that particular portion of downpipe/pre-cat. I may go through the route of cutting the cat and welding a new one in its place. What type of cat do I need to use? There's threads that mentioned using a specific type but there were lots of conflicting and missing info. Its going to be a pretty tight fit too so a regular sized cat won't fit down there. I was wondering if theres a specific make and model of cat that people are using that'll fit/work.

[idlafie]

Have you tried posting in the Want To BUY section here on Zilvia. I'm sure someone here on Zilvia has a S14 cat sitting in their garage collecting dust. Or you can always try your local junk yard.

I couldn't tell you specifically which cat to use. You can always take a drive to your local muffler shop & see what they would recommend you use. Whatever you do, make sure the muffler shop DROPS your exhaust & cuts the flanges off the OLD cat & welds it to your NEW cat. You want to make sure everything bolts on & off. Makes it easier to service the car in the future.

Anyhow, hope this helps.

[beefcake6681]

I appreciate you taking the time to respond. I will go ahead and try that.

[fliprayzin240sx]

Or just fix the leak, change the J pipe cat to a straight pipe and add a regular cat under the car where the dummy cat is at.