Advice for stripped threads upstream oxygen sensor exhaust manifold

Car is just bought by a kid just learning to drive (he's 16). 2004 Mitsubishi Lancer ES
Neighbors asked me to teach him how to replace the oxygen sensor (due to emissions code).
The threads were stripped and "filled" with some kind of hardened "metal paste".
The new part is a Denso 234-4739 (marked 485000-4060, 07U05) The old part is a Denso (marked 234000, 8643, 07E23)
What would you suggest? - Tap the threads? (22mm hex nut) - New exhaust manifold?
http://www.bild.me/bild.php?file234632o2sensor01.jpg
http://www.bild.me/bild.php?file €64061o2sensor02.jpg
http://www.bild.me/bild.php?filec99144o2sensor03.jpg
http://www.bild.me/bild.php?file 74232o2sensor04.jpg http://www.bild.me/bild.php?file ”18974o2sensor05.jpg
http://www.bild.me/bild.php?fileA83674o2sensor06.jpg
http://www.bild.me/bild.php?fileX56176o2sensor07.jpg
http://www.bild.me/bild.php?file486734o2sensor08.jpg
http://www.bild.me/bild.php?file –94112o2sensor09.jpg
http://www.bild.me/bild.php?fileP19152o2sensor10.jpg
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replying to Arlen Holder, fozz89 wrote: You could try and tap. (cant see your pictures BTW) It depends on how much material is missing from the original threads. I dont know my way around Jap cars too well but usually with the right equipment you can just flash the PCM and make emissions BS go away permanently (along with your catalytic converter) More HPs, Better mileage, more crying liberals.
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On Thursday, August 2, 2018 at 8:14:06 AM UTC-4, fozz89 wrote:

I'm a conservative and I don't think it's a good idea to modify cars so they pollute either. Amazing that someone could turn a simple repair into that nonsense. Also, with the emissions BS going away permanently, I wouldn't be surprised to see it have lower mileage too, because the computer winds up running it open loop, guessing at what's going on, instead of running it closed loop.
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On 2 Aug 2018 06:59:23 GMT, trader_4 wrote:

There's a reason I didn't respond to that suggestion of removing emissions. There is absolutely zero chance we are going to mess with the emissions. Zero.
It's going to be street legal smogable or we won't do it.
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Arlen Holder wrote:

IF it were my car and IF the manifold is steel, I would remove the manifold, then remove the square nut, and weld or braze in a thin-ish nut of appropriate thread size. If no thin-ish nut is available then make one with the dremel. The sensor needs to be in the flame and also have good thermal conductivity to the manifold.
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On 1 Aug 2018 21:25:57 GMT, Paul in Houston TX wrote:

I had not thought of putting a new nut on. I'll look in the morning to see if the nut is the only threads. I'm sure the sensor has to be "in" the stream of hot vapors.
It seems to be cast iron. Aren't they all that way? (It's rusty.)
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On 08/01/2018 09:31 PM, Arlen Holder wrote:

Back to your friendly Loctite dealer for the Form-A-Thread kit? Trip to a junkyard for a new manifold if replacing it isn't too painful? Helicoils?
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On 1 Aug 2018 22:26:00 GMT, rbowman wrote:

Seems to me the choices are... a. New or used manifold (if it's not too hard to replace) b. Drill it out and helicoil it (nothing to lose really) c. Clean it up with a tap (I don't have the tap, which won't be cheap) d. Shove it in there with epoxy (I hate that idea so I don't want to)
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On 1 Aug 2018 23:30:57 GMT, Steve W. wrote:

Thanks for confirming it's the same threads as a spark plug, which, at the moment, seem to be 18x1.5 for them.
Googling, it seems cast iron isn't easy to weld, and that the plug rethread might work, but, the heat cycling has likely hardened the bung nut, such that it's a LOT harder (some say) to deal with than a spark plug thread which is typically in aluminum engine blocks (they say).
Searching for this "plug rethread kit", is this the $62 kit you speak of? (Amazon.com product link shortened)
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Arlen Holder wrote:

Plug threads are M18 x 1.5 or M14 x 1.25 on most automobiles. The M18 are the older plugs and O2 sensors and the M14 are the common peanut plugs used these days.
Heat cycling will have made the iron harder to work with but the tools used are designed to handle that.
That kit would work but I like using a solid insert myself, they hold up better. I use timesert myself.
If you check with many of the chain parts stores they may have a thread repair kit as a "loaner tool". You "rent" the tool use it, return it in good shape and get your money back. You pay for the insert(s) you use. A lot cheaper than buying the kit for a one time repair.
--
Steve W.

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On 2 Aug 2018 08:02:40 GMT, Steve W. wrote:

I went to O'Reilly's and Autozone today, where the loaner tap and die kit at O'Reilly doesn't come close to the M18x1.5 needed here but they do sell the M14x1.25 thread chaser for those smaller spark plugs: http://www.bild.me/bild.php?file `43628o2sensor11.jpg
I bought from Autozone this M18x1.5 thread chaser and will get the kid to work with me in a couple of hours before nightfall and report back. http://www.bild.me/bild.php?file …22268o2sensor12.jpg
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On 8/2/2018 1:44 AM, Arlen Holder wrote:

Β *NO*!! That kit uses standard helicoil inserts , which are fine if you're using spark plugs that use a crush washer to seal .Β  What you want is similar to one I have and have used , mine is a NAPA auto parts #770-3223 "Sav-A-Thread" kitΒ  - it's for 14 mm plugs but you need the one for 18mm plugs . For the heat cycle hardened threaded bung you need to heat it red hot with a torch and let it cool slowly - even if (and it has) the steel has absorbed carbon from the exhaust gasses the slow cool will anneal the metal (will help a great deal if the manifold is hot too ...) . If you can cut it with a file , this kit will work . One suggestion - drill the hole out enough to clean up the old threads plus a bit , it makes the ream/tap operation much easier . This kit includes a punch that upsets the top edge of the insert (solid metal insert) knurling into the threads to keep it from backing out . This kit is made by helicoil , you may be able to find it at another retailer - I bought another from O'Reilly Auto Parts because this one was "lost" in the move when I left Memphis for rural Arkansas .Β  I've used these kits twice , in 2 different vehicles with excellent results . Both were "hemi" type OHC motors with the spark plug straight down the center of the valve covers . Both required machining guide bushings to be sure I got the hole straight (I have a machine shop , it's a "hobby") and both have run for many thousands of miles trouble-free . Good luck !
--
Snag
Yes , I'm old
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On 2 Aug 2018 16:33:44 GMT, Terry Coombs wrote:

Thanks for that advice based on your experience, since I have zero experience with these things.
I saw that kit at O'Reilly's which I photographed on their counter. <http://www.bild.me/bild.php?file `43628o2sensor11.jpg>
The sort of good news is that the thread chaser bottomed out entirely by hand, without any strength required whatsoever, but the sort of bad news is that it didn't clean up much as a result: <
http://www.bild.me/bild.php?file885168o2sensor19.jpg
Still, at least that "jb weld" or "epoxy" or whatever it was, seems to be cleaned out. <
http://www.bild.me/bild.php?filei98492o2sensor20.jpg
The thread chaser really didn't clean up the threads as much as it pushed out the jb-weld-expoxy-whatever stuff from the valleys. <
http://www.bild.me/bild.php?filec73378o2sensor21.jpg
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On Fri, 3 Aug 2018 05:47:18 -0000 (UTC), Arlen Holder

What did you want it to do? A "thread chaser" is supposed to clean foreign material out of the thread. If the threads are not badly deformed, it will NOT remove metal.
You now have a pretty fail percentage of a thread - - -
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On 3 Aug 2018 18:00:56 GMT, Clare Snyder wrote:

Thanks Clare.
To answer your question of "what did you think was gonna happen?", I pretty much was hoping it would "feel" like I was tapping new threads, as I've tapped things before.
But it just felt loose.
Still, it tightened the last 1/8th of a turn, so, if that's enough of a "bite", then I'm happy.
I don't know how to *test* if the lambda sensor is leaking, but there's no sound coming out of it (of course, the engine is loud so the sound would have to be huge like it was when we moved the car a bit with the sensor out).
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On 08/01/2018 11:39 PM, Arlen Holder wrote:

The helicoil route won't be cheap either. The epoxy route is redneck engineering at its finest but this is a 14 year old beater, right?
As an aside, general purpose epoxy isn't a good idea for an exhaust manifold.
https://www.jbweld.com/products/highheat-epoxy-putty
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On Thu, 2 Aug 2018 05:39:22 -0000 (UTC), Arlen Holder

It's a spark plug thread. I bougrt a thread chaser that does 14 and 18mm threads for under $10 Canadian.
Better yet, pick up an 18mm X 1.5 tap from a local tool supplier - Hanson (Irwin) 2459 is about $12.95 List -
About $36 from Fastenall
Even hOME dESPOT CAN GET IT FOR YOU - PART NUMBER dwtb18x1.5 - $21.14

Don't even THINK about it!!!
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First step is clean out the existing threads - do NOT use a form-a thread type product - needs to withstand high temperature AND be electrically conductive. (some sensors don't need the ground, but many do)
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On 2 Aug 2018 13:48:38 GMT, Clare Snyder wrote:

Hi Clare, You've always been right, over the years, on everything!
I will always strive to take your advice, as you have the experience I lack.
I did clean out the threads late this afternoon just before nightfall: <
http://www.bild.me/bild.php?fileY32805o2sensor28.jpg
After removing the upper radiator hose to get a straight shot and hand threading the oxygen sensor thread chaser a few times up and down into the hole, I hand tightened the new oxygen sensor (which came with a crush gasket like spark plugs do) into the threaded bung. <
http://www.bild.me/bild.php?file%91539o2sensor22.jpg
When it met a slight resistance, I used the crows foot, still by hand: <
http://www.bild.me/bild.php?file871206o2sensor23.jpg
Then, when it bottomed, I gently applied leverage ever so slightly: <http://www.bild.me/bild.php?file „31124o2sensor25.jpg>
I figured it would be better loose than too tight, as I didn't want to risk the threads, but I did snug it down with, oh, about 20 foot pounds in the last 1/8 turn or so. Then I transferred the old metal bracket to the new oxygen sensor: <http://www.bild.me/bild.php?file 31967o2sensor24.jpg>
And I buttoned back up the heat shield & routed the oxygen sensor wiring: <
http://www.bild.me/bild.php?fileH53481o2sensor26.jpg
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On 1 Aug 2018 21:41:29 GMT, Bob F wrote:

I guess it can't hurt. I can contact Denso to figure out the thread pitch for their O2 sensors.
I was thinking of cleaning up the threads, but they look really bad. How on earth can ANYONE do that to a bunch of threads?
What did they do? It's not even hard to get to ... it's right there ... in front.
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