So i recently bought a 1990 f250 xlt lariat 460 and need a new exhaust from the cat back. I went to look at the cat on now and i found this pipe hanging loose just sitting on top. There is what looks like a hole that is welded up or something. The pipe goes into the engine and i cant really tell what it is. Do i need to buy a special catalytic converter? Also what size inlet is stock for the cat? Thanks for taking the time to read and i appreciate your help!

 

that is coming from the smog pump, it pumps air into the converter so it will burn up any unburned gas that made it through the engine.

 

So thats why it smells like gas so much. I need to buy a cat that has that hole right? And then weld the tube onto the cat? Thanks!

 

OEM style replacement converters will have the air injection tube port. The F250HD/F350 used an oval inlet converter that tends to be pricey.

 

Welcome by the way. Check to see if the rest of your smog junk is still there first. On my 5.8 a few years newer the air pump is belt driven on the passenger side on about the same plane as the crankshaft. Couple rubber hoses coming out of it I think. They lead to an air box on the passenger fender well and up and around behind the intake over to driver side and it's ugly. Some would say unnecessary.

If all that is in place, you COULD buy a factory cat and return everything to stock if you're wealthy. If it's not all there, congratulations. Are you in a state/county with emissions testing? Is it privatized where you can maybe get someone to let you slide? Are you replacing the cat back due only to rust, or for another reason?

 

Im replacing because it is pretty rusty and the outlet of the cat has been chopped off and i cant put a pipe onto it. Is the air tube absolutely necessary? Could i just buy a cat without it? Emissions are not an issue.

 

It's welded closed so how necessary could it be? Lol

Use the search this forum button and type in smog delete, it's also called AIR system or something like that. Look for the other cluster of items in your engine bay as well. Might already be mostly removed.

Since its already not functioning as designed, you can replace the cat with one that doesn't have the tube.

I think your first problem you need to figure out is the gas smell though. How is the tune up? Is the gas smell coming straight from the exhaust, or is one of the tanks leaking or seeping when too full? Is there a rotted fuel line? Is it 100% of the time that it smells like gas?

 

You can buy aftermarket 3-way converters that do not require an air injection tube.

 

My pipe broke in that exact same spot. The exhaust shop I took it to (when I replaced my missing muffler) welded it shut at the lower pipe. It just hangs there now. I don't have emission testing in my state so I'm fine with it.

Anyone know what I'm safe to remove along with this pipe? I'm thinking the EGR could be blocked off and removed correct?