o2 bung plug seized?
 

Hey folks! I tried to find a previous post on this with no luck, which further suggests to me that I am doing something dumb. I have an MSM; installed the FMLE kit a couple years ago. This year I'll do a Megasquirt, and I figured I'd install the wideband first. I removed the FM downpipe and I simply cannot get the bung plug ahead of the cat to release. I've got a 10mm allen wrench in it and an 18" pipe on it for leverage, hit it with penetrator twice (waiting overnight) and the thing will. not. budge. I'm worried about rounding the inside of the plug. What the heck am I missing?

Heat and beat. Anything exhaust related that's been installed for awhile tends to fight you.

As above, heat, lube, and then force.

if it's super stuck you can always try shocking it, heat it with a torch then tip cold water on it.


Otherwise, just slam it with an impact driver.
https://cimg0.ibsrv.net/gimg/www.mia...e646bf9625.jpg

their combo of twisting and impact often breaks loose even the most stubborn things.

Whelp it's not as if I've got a track record doing anything correctly, but this was my process when I had to remove a stuck o2 bung freeze plug on a used exhaust I picked up...

1. Completely round out hole with torx bit and breaker bar.
https://cimg5.ibsrv.net/gimg/www.mia...d13129452f.jpg

2. Center drill freeze plug and try using left hand helix easy-out cone bit thingy. Succeed in doing nothing but widening the hole.
https://cimg1.ibsrv.net/gimg/www.mia...48cc2181f7.jpg

3. Try a bigger left-helix bit and an oxy-acetylene torch to ease things along in the right direction.
https://cimg3.ibsrv.net/gimg/www.mia...d5e5df9432.jpg

4. Accomplish nothing bit breaking tools and snapping a hardened steel bit off inside the freeze plug because drilling out "stainless" is too easy.
https://cimg2.ibsrv.net/gimg/www.mia...62191c233e.jpg

5. Declare vendetta against the clearly inferior freeze plug. Tell yourself you have the upper hand, push any sane thoughts out of your mind, and shut your eyes to load some far-too-nice carbide tooling into the cnc. Plunge cut and helix out until nothing but ten or twenty thou of freeze plug remain alive and standing.
https://cimg8.ibsrv.net/gimg/www.mia...5c209d4503.jpg

6. Bask in your clear superiority over lesser metallic beings, chase threads with appropriate NPT tap and gobs of cutting oil, and wonder how much time is left in the day you've clearly wasted.

https://cimg7.ibsrv.net/gimg/www.mia...e35c8609c2.jpg


So yeah, in my obviously uninformed opinion, if step 1 + maybe a map torch doesn't do the trick I might just pay someone to weld on a new bung.

Sometimes, exhaust parts just suck.

Glad to see you're making progress.

At work I put a harbor freight jack handle on my ratchet and if it doesn’t come loose I’m welding a new one on. Often by the time it is out, the threads are gummed up anyways. Anti seize seems to work, but that’s obviously gotta go on originally. I’ve also used a big aluminum crush washer, not really sure if that helps, because it’s usually the threads that go bad.

If you can weld another bung on, that means you can also weld a 3/4" nut onto the stuck plug. For me, the heat of welding on a nut is enough to also help break the threads loose.

For re-install, use Nickel based anti-seize. Ford parts houses have it in stock, usually.

ROTFL, this totally made my day. Thanks Spaceman Spiff!!

Thanks to all for the advice. Wish I'd thought to remove the plug and add anti-seize when it was new. I'll try 1. butane torch and hex key with extension; 2. butane touch and impact driver; 3. take it to my local shop and have them try it, or failing that, weld in a new bung for me. I have neither the tools nor the skills to do that myself. One day...

Consider that a competent fabricator can add a new bung in about 15 minutes. I wouldn't spend more than about 10min trying to remove the old plug, and I certainly wouldn't drill straight through it. If you've got 10 minutes into the project, bask in the knowledge that it will never come out, and add another bung next to it. :)

1st step - Aerokroil...

Failure achieved...
 

For posterity, did try repeatedly to torch it, PB blast it, and impact drive it. Nothing would make the thing release, and eventually I did strip the plug. Brought it to my shop, they drilled it out, but damaged the old bung in the process, and so welded a new one in. It was worth a shot though. Thanks to all for the advice!