exhaust leak, o2 sensor stripped threads

[greenleg88]

i know this is a subaru forum but this is a technical question regarding a 2003 toyota corolla...

 

and i know people on here are much more helpful than the guys on the toyota forums..

 

 

so. when i replaced the o2 sensor a few months ago, the threads were stripped because of some mystery object dislodging the original sensor and denting it from the inside as well is causing the threads to strip..

 

we put the new o2 sensor in and since the threads were stripped, we tightened it till it was snug and left it at that.

 

 

just tonight, the o2 sensor popped out and it sounded like i was driving a riced out civic with a fart can...

 

any suggestions as to what i should do? the car seemed to be running strong when the o2 sensor was sitting snug... i was thinking to just put some heat rated loctite or somethign in the threads and letting it sit as snug as i could...

 

 

any one have any ideas what kinda paste i should use. or suggest against this?

 

thanks a lot.

[porcupine73]

Hmmm.mhmmmm..mmhm...well if you're looking for a fast fix (vs something like a helicoil), it'll have to be something that can withstand high temperatures like at least 1000F I'd say.......not sure if teflon tape can withstand that.....maybe some kind of nomex packing or something like that.....there are thread repair kits that are sort of like jbweld but not sure what temp those can withstand.....loctite maybe but loctite is not relaly intended to bridge gaps which is what you have.....

[greenleg88]

hmm i just looked up what helicoil is... and how would that work?

[porcupine73]

Well the helicoil is kind of a pain because you have to drill out the hole to a larger size, then put in the helicoil, not impossible, but more work/skill required than jb weld for emaple. Helicoils can be surprisgnly pricey too.

[greenleg88]

how surprisingly do you mean by surprisingly... like 20 dollars surprising or liek 80 dollars surprsing... or more....

 

i saw jbweld just now at walmart.. it doesnt have a heat rating.. i did see this though... and this is also similar to what my friend told me about..

 

http://www.permatex.com/products/Automotive/automotive_gasketing/gasket_makers/auto_Permatex_High-Temp_Red_RTV_Silicone_Gasket.htm

 

cept thats only rated to 650 degrees... anything else.. im mostly looking for an adhesive fix...

 

 

thanks!

[NorthWet]

If it's worth doing, you might as well make it last. I don't think any adhesive/filler is going to work out. The O2 sensor bung threads are a common spark plug thread (18mm??... it is the larger end of a spark-plug thread chaser) so heli-coil spark plug repair kits ought to work.

 

Are you sure it is the bung threads that are stripped? Typically, the threads weld/peel off of the O2 sensor, requiring the bung's threads to be chased with the aforementioned spark-plug thread chaser.

[joostvdw]

I don't know how much room there is and how handy you are, but you could just weld up the current hole and make a new bung somewhere else.

[lostinthe202]

Are you sure it is the bung threads that are stripped? Typically, the threads weld/peel off of the O2 sensor, requiring the bung's threads to be chased with the aforementioned spark-plug thread chaser.

 

This is my vote. I don't know what a spark plug repair kit with a chaser costs, but you could pick up a tap for less then 20 bucks and chase the threads. Should work unless the bung got really deformed.

 

I've successfully repaired cracked engine cases on motorcycles with JB weld, but I doubt it would be up to the heat of exhaust.

 

Good Luck!

[porcupine73]

Hadn't thought of the chaser. I think even pepboys has the lisle thread chaser, it's tapped for the common spark plug sizes maybe one of those matches the o2 sensor thread. If the o2 sensor feels way too loose in the hole then maybe it is stripped out. Maybe some fiberfrax would do the trick, this place is near my work http://www.fiberfrax.com/

[lostinthe202]

Hadn't thought of the chaser. I think even pepboys has the lisle thread chaser, it's tapped for the common spark plug sizes maybe one of those matches the o2 sensor thread. If the o2 sensor feels way too loose in the hole then maybe it is stripped out. Maybe some fiberfrax would do the trick, this place is near my work http://www.fiberfrax.com/

 

Interesting looking stuff. Looks like the 970 paper at 1/32 thick might squeeze in there.

[Rooster2]

JB weld is an amazing product. It just might be able to handle the head of a cat converter. I have never tried this, but have heard that you can use JB weld to repair stripped threads. Try this..........clean out the hole the absolute best you can with solvents, light sand paper, etc. and dry thoroughly. JB weld must have a very clean surface to bond to. The cleaner the better. Apply a light coat of JB weld to the cat threads. Let it set up, but not get completely dry. Apply a release agent, something like anti-sieze or similiar to the threads of the o2 sensor. (This will prevent the o2 sensor from sticking to the JB weld, and allow you to unscrew the o2 sensor should you need to replace it in the future.) Gently screw in the sensor by hand if possible, but don't fully tighten down the sensor, as this will damage your newly formed JB weld threads. Allow the JB weld to harden over night, or better yet allow 24 hours before fully tightening up your o2 sensor. Be careful when tightening, do only a nice easy snug low effort tightening. Avoid a hard tightening effort, as that too could damage your new JB threads.

 

Good luck if your should try this approach!

[MorganM]

I don't know how much room there is and how handy you are, but you could just weld up the current hole and make a new bung somewhere else.

 

I agree with Joost. The bung is really cheap. Any exhaust shop worth their while could do this in under an hour. Fill in the old hole and weld in a new bung.

 

Or replace the whole cat. converter. Yeah, I know, they are expensive and you can't get one second hand legally. However it's an option.

[idosubaru]

chase the threads in the exhaust.

 

at this point the threads on the O2 sensor are likely damaged as well. chase those with a die as well. a fine file will work too to clean them up if they're not really bad, which they probably aren't.

 

assembly with non-permanent lock tite.

 

heli-coil or timeserts would also work but they can run $40-ish.

 

taps and dies are expensive as well. a shop might charge $50.

[greenleg88]

alright so a total update on my current situation.

 

 

i have called many shops and none of them had the tap i needed. someone told me it was a 14 by 1.5 mm tap that i needed. i searched EVERY WHERE for that tap. nobody had it. i figured id get a bolt that size so i could chase the threads.. and if i could find my dremel, id cut down the bolt perpendicularly to make a makeshift tap.... i find the bolt ... which is really a wheel stud with no hex top.. so it would have been difficult to drive in anyways.. and its the wrong size.

 

so i really dont know what the size is that i need right now. ill look into those spark plug taps..

 

 

so the threads on the bung are pretty messed up. but only at hte beggining .. i used a mirror and couldnt really tell if its saveable.. but eitherway.. i dont have anythign to chase it with..

 

i ended up using some permatex.. the gold stuff. its good to 700 intermittent. someone said the jb weld was goign to crack cuz of the heat.. and i didnt want to use thermo steel or whatever that is.. the cold weld stuff...

 

i put the permatex on.. waited 24 hours.. drove it.. and as i was on the way home.. i heard the sensor pop out again.. and that was right before a 400 mile trip i planned to go home...

 

i let the car cool for an hour and tried using the permatex again, and i used a really thin cable thats used for hanging pictures.. i got that around the headrs and looped it on.. then i used a drywall screw to twist hte cable and tension it.. its actually holding on REALLY REALLY incredibly well.. considering its only a temporary fix... but it might have to stay for a bit.... because im going back to school..

 

 

Threading

 

the threads on the bung are gone, there are two rows of threads on the sensor that are a little ugly.. but if i could get a confirmation on the size, i will order the tap and die set. are all 02 sensors the same size? this is a 2003 toyota corolla.

 

and if rethreading the bung doesnt work, ill have to find a new header from a junk yard or osmething.. a few people have been telling me about how you cant realyl weld cast... and thats what the manifold is...

 

any comments...?

 

thanks for al the responses.

[lostinthe202]

i have called many shops and none of them had the tap i needed.

 

Have you tried calling a dealer and seeing if they have the thread size listed?

 

i figured id get a bolt that size so i could chase the threads.. and if i could find my dremel, id cut down the bolt perpendicularly to make a makeshift tap...

 

I don't really understand what you would do with the dremel, but bolts don't make good taps. Taps are both made from a hard material (harder then bolts) and have threads that are "teeth" and will cut away and reform the threads in the bung. The die works the same way, just the inverse. Using a bolt to chase threads usually ends up with a stuck or broken bolt or even worse threads

 

so i really dont know what the size is that i need right now. ill look into those spark plug taps..

 

If a dealer isn't able to tell you definitively what the thread size is, then get a couple of guesses and order a bolt and nut from here -

 

http://www.mcmaster.com

 

You can also get a tap and die from them. They typically ship the same day you order and, depending on where you are, it will usually get to you within a day or two.

 

the threads on the bung are gone, there are two rows of threads on the sensor that are a little ugly..

I would be amazed if the threads in the bung were wiped out but the 02 sensor only had a couple of messed up threads. Chances are the bung threads just looked wiped out 'cause they are rusty or maybe have never-seize caked in them or something.

 

are all 02 sensors the same size? this is a 2003 toyota corolla.

 

This being a Subaru forum, you may have a tough time getting answer to this question:)

 

Though, many cars have more then one 02 sensor, and those are likely the same thread so you maybe could compare.

 

a few people have been telling me about how you cant realyl weld cast... and thats what the manifold is...

 

It is possible to weld cast, but it is more persnickety then other materials and you'd have a tough time doing it with your buddy's garage welder. A replacement header from a JY might be the ticket as it might be cheaper then buying a tap and die only to find out the threads are beyond repair. But a 2003 is a little new for the JY's so be prepared to search around awhile.

 

Good luck.

[jp98]

What ever you end up doing is going to cost. Here is the THREAD CHASER that you will need to clean up the bung if that is the problem. Now if the threads are beyound repair you will need to buy a HELICOIL KIT witch isn't cheap. All O2 sensors threads are aluminum so unless the manifold is aluminum also you should be ok with the thread chaser. The best way to actually work on it would be to get it off the car and onto a bench where you can see what you are actually doing.

 

Jim

[lostinthe202]

All O2 sensors threads are aluminum...

 

Not all, the two on my '96 OBW aren't. Is this a new thing?

 

That thread chaser for 7 bucks looks like the most economical way of fixing this.

[jp98]

My bad info then on the O2 sensor material, but it would make sence to have two different hardness of materials. It is possibly a lot like your oil drail plug and the bung on the oil pan althoe they are both made of steel. The bolt/plug is made of a softer material so that you strip the bolt/plug instead of the bung on the pan.

 

Jim

[Buick350X]

Same boat here and JBweld does work just fine but the stuff doesn't provide a good ground, which makes it not work right, did for a bit. I was going to buy one of them weld on yourself bungs for when ya make headers [summit catalog], and weld it on after griding knocking the old one off. But as is our Forest run fine even tossing a bank3 02 error all the time. Its the last one in the chain for us. DOn't wanna know what it cost to replace the cat.

[Gnuman]

OK, I see the lot of you talking about how to patch the o2 sensor back into this cat. Please note that the original threads were stripped "by something hitting it from inside, denting the o2 sensor" and knocking it out. The second o2 sensor was also knocked out from the inside. Something big is loose inside that cat, and this will continue to happen until that cat is replaced with one that has all the pieces firmly secured in place. Unless the cat is seperate from the header, and the o2 is actually in the header, not the cat, you will not be able to buy the piece that holds the o2 sensor used. By law, it cannot be sold used. you have to get new, if the o2 sensor is in the actual cat (as most I've seen are). Trying to get it fixed cheap is all fine and good, but let's actually get it fixed for good as well.

 

We need to know what it was that knocked the old o2 sensor out of the threads in the first place in order to prevent it from happening again.

[Buick350X]

IN my case and I bet the others, when you took the old 02 out when it went bad, the threads came out with it. So there are no threads to get a new one to seal or tighten right.

[greenleg88]

OK, I see the lot of you talking about how to patch the o2 sensor back into this cat. Please note that the original threads were stripped "by something hitting it from inside, denting the o2 sensor" and knocking it out. The second o2 sensor was also knocked out from the inside. Something big is loose inside that cat, and this will continue to happen until that cat is replaced with one that has all the pieces firmly secured in place. Unless the cat is seperate from the header, and the o2 is actually in the header, not the cat, you will not be able to buy the piece that holds the o2 sensor used. By law, it cannot be sold used. you have to get new, if the o2 sensor is in the actual cat (as most I've seen are). Trying to get it fixed cheap is all fine and good, but let's actually get it fixed for good as well.

 

We need to know what it was that knocked the old o2 sensor out of the threads in the first place in order to prevent it from happening again.

 

 

first off thanks for the help.

 

and to clarify.. this is the first o2 sensor. as in it is directly on the exhaust manifold. its not behind the cat... so i dont think something from the cat broke off and hit it..

[greenleg88]

Have you tried calling a dealer and seeing if they have the thread size listed?

 

 

 

I don't really understand what you would do with the dremel, but bolts don't make good taps. Taps are both made from a hard material (harder then bolts) and have threads that are "teeth" and will cut away and reform the threads in the bung. The die works the same way, just the inverse. Using a bolt to chase threads usually ends up with a stuck or broken bolt or even worse threads

 

I would be amazed if the threads in the bung were wiped out but the 02 sensor only had a couple of messed up threads. Chances are the bung threads just looked wiped out 'cause they are rusty or maybe have never-seize caked in them or something.

 

 

 

This being a Subaru forum, you may have a tough time getting answer to this question:)

 

Though, many cars have more then one 02 sensor, and those are likely the same thread so you maybe could compare.

 

 

 

Good luck.

 

 

 

thanks for that. well wiht the dremel i intended to make a makeshift tap.. it was really the best possible idea since i couldnt find the tap for it..

and the first two threads on the bung are pretty much flattened and ripped of. so if its smoothed out im guessing it cant be saved. but im not really sure the condition of it right now. and thers def never been anti seize compound on it..

 

the o2 sensor is kinda tied on temporarily for now.. its doing the job.. and its only a temporary fix till i can get back to the car and finish it properly...

[lostinthe202]

Ah, I think I get it about the dremel. Well at least the current setup is working for the moment and will buy you some time.

 

If the first two threads are really messed up then yeah it might be tough or impossible getting enough good threads on there to get a seal. But at $7 for the thread chaser, it's probably worth a shot to try. The next cheapest option would be to buy a used manifold. I see some on http://www.car-part.com for around $30. Pick up another gasket and you're ready to go.

 

Good Luck!

[greenleg88]

hmm. Thanks a lot!