Repair/replace Exhaust Flange on Catalytic Converter (91 Ford Truck)





Introduction: Repair/replace Exhaust Flange on Catalytic Converter (91 Ford Truck)

replace a rusty exhaust flange connector on a catalytic converter where it connects to the exhaust manifold. This will save replacing the entire catalytic converter as in this application the end of the pipe is flaired and/or in some applications the flange is spot welded to the end of the pipe.

Step 1: 1 Parts Needed, TWO Exhaust Flanges for the Proper Size Pipe. (example #240880 EXHAUST PIPE FLANGES JC Whitney .com) 2 Small Nuts and 2 Small Bolts (sized by Holes Drilled Later)

Step 2: Tools Needed; Hacksaw or Powered Cutter Wheel Etc.; Drill and Bits

Step 3: Cut Flanges As Indicated

Step 4: Place One Flange Over the Other and Drill Holes As Indicated.

Step 5: *** NOTE*** Make Sure That the Pipe and Manifold on Your Vehicle Are Cool Enough to Work On.

Step 6: Cutoff/remove the Old Flange From the Pipe.

Step 7: Install One Flange Over the Pipe and Then Slide the Other Half Over the Pipe.

Step 8: Align the Flanges and Secure Together With Nuts and Bolts Through the Drilled Holes.

Step 9: Slide the Flange Into Place and Secure to Exhaust Manifold.

Step 10: For Broken/corroded Studs Bolts on Exhaust Manifold Use (Example) 470112 CLAMP-A-STUD W/O HEAT RISER... See JC

The completed repair



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    10 Discussions

    Exactly, to a T, what I was looking for, you are brilliant. Thanks for doing my homework. I owe you a coke.

    Have not seen work like that in a long time. every one want's to weld. Good luck finding a sdud clamp.

    from reading this it seams to me that your calling the exhaust manifold or the Y-pipe the "converter"

    dont do that any more.

    1 reply

    NO , as illustrated by the photo the exhaust manifold is connected to the catalytic converter ..

    I like your do-it-yourself attitude. I truly appreciate it and I am a patron saint of the local salvage yards. However, I have learned to not touch exhaust systems. Call around your local small shops (NOT Midas, etc) and ask them how much it would be. I have broken more studs, skinned more knuckles, gouged out more parts of my hand and generally caused more bodily damage dealing with exhaust systems than I have with all other automobile work and sports combined. Thanks for letting me know about the JC Whitney Clamp-a-stud clamp. It's a trick part that will come in useful one day when I ignore my own advice :-)

    3 replies

    I did not hesitate to tackle this problem , yes there are some exhaust problems on certain vehicles i would not repair without the proper tools and equipment if time was a consideration. Since this truck has a lot of ground clearance and the exhaust system is easy to get to I have replaced most of the components from the converter to the tail pipe. However I have learned that skinned knuckles can be avoided by wearing work gloves and recommend protective eye wear. I can usually count on replacing studs/clamps etc. by looking at them and assuming they will break. How this repair would cause "bodily damage" is questionable. The point of many of these Instructables is that the reader assumes and assess the risks whether baking a cake or constructing a jet engine in the pursuit of knowledge and experience. I do not call many repair facilities and don't know if they would do a repair like this or just replace the entire catalytic converter. Good Luck leebryuk

    Chillax man...I said that you did a good job. I also thanked you for the trick studs from JC Whitney. I wear varying gloves (from nitrile to leather knuckle beasts.) Hands still slip every so often and I bruise something (fingers, wrists, forearms, elbows, etc.) That's what "bodily damage" means. Me and exhaust systems go way back and I don't care for working on them. I have to yank my engine from my Saab 900 to replace the front oil seal (for those who are not aware of the Saab magic, the engine is inline, but is ass backwards.) Some people can do it if they have thin arms. I don't have thin arms, more of a pop-eye look. So I have began the regiment of PB blaster a month ahead of time. That means I wait for the engine to cool down and soak the living h*ll out of every nut and bolt relating to the exhaust. I also have an impact wrench and will go to church before I attempt to loosen that first exhaust stud. And yes, repair shops will weld a new flange for you. Call a small one and ask around. Tell them what you want. Bargain a bit (can you help me with that price?). Don't show up in your sailing regatta hat. Bring some Gatorade with you as a thank you. You'll be surprised what a 12 pack of Pepsi will help you with. They can get a converter off in seconds, weld a replacement flange and have it on within another 10 minutes. Also, generic replacements abound for $40-60 nowadays. The moral of this story, play nice with your local small shops, show gratitude with cola, DIY and just relax as a whole.

    yes leebryuk, thank you for your comments, I think I get the point of "Chillax man", but I have posted this repair as an Instructable . Had I utilized a local repair shop, would I post an instructable stating that to repair a exhaust flange would be to bring it to a shop and have it welded? Some people consider some Instructables a sort of hack but that's who we are. I have friends who I would consult should the need be, but the do-it-yourself creed says use your own resources and knowledge first, save $$$ and post here for all to see. It's fun and relaxing as a whole !!

    just to let you know , this repair is still in place today