Advice for stripped threads upstream oxygen sensor exhaust manifold

 *NO*!! That kit uses standard helicoil inserts , which are fine if you're using spark plugs that use a crush washer to seal .  What you want is similar to one I have and have used , mine is a NAPA auto parts #770-3223 "Sav-A-Thread" kit  - 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 .  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 !
Reply to
Terry Coombs
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Hi Clare, Your advice has always been spot on!

At O'Reillys (my closest auto parts store), they only had the 14mmx1.25 spark plug chaser which is too small.

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But at Autozone and Napa, they had what appears to be the right-sized chaser labeled as an "oxygen sensor" chaser at M18x1.5 threads:

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So I will try that later on today when the neighbor is home from work and when the kid is there as I insist that he work with me and not just use me as a slave (I want him to learn to be able to do things on his own).

(I already made him change a tire and mount and balance it with me, where I was shocked at how utterly EASY a 14-inch tire is to mount compared to the SUV tires!).

O'Reilly's quoted 800 and change for a new exhaust manifold where the problem is that the catalytic converter is integral with it, so, I think a junkyard is iffy since a junkyard cat may be problematic, don't you think?

The kid has to pay for all the parts (I'm paying for the tools), where he doesn't have that kind of money - but if the car is to be repaired, it's one of the options.

Luckily, a friend whose kid can weld said he's help if needed, so I can remove the exhaust manifold, if necessary, and we'll try tack welding on a bung.

I don't weld - but from what I read, you can't really "weld" cast iron (which I assume the exhaust manifold to be) but it could be steel for all I know (how can I tell? It's a 2004).

The bung itself is mild steel (apparently) which has been perhaps heat treated by a billion cycles in the engine into being hardened steel.

So what I've read is maybe we can drill out the old heat-hardened steel and then tack weld in a new mild-steal bung or put in the timeserts/helicoils.

One problem, some say, with helicoils is that an oxygen sensor tip has to be in the flow, so the threads can't project post the metal of the manifold.

I am VERY CAREFUL where I just did my bimmer, which has two upstream Bosch lambda sensors, the back one of which you can't get your hand on, and they came out perfectly and threaded in perfectly even though I couldn't even get close to the rear one.

This Mitsubishi Lancer ES has the thing right in our face! It couldn't get easier. And yet, someone screwed it up. Sigh.

Yup. The threads on the sensor are all chewed up. The paste is perhaps epoxy or JB weld, but you're right. The electrical connection likely sucked. Who on earth would do that? I can't believe it given how EASY this sensor is compared to all the rest I did.

For example, I recently did the neighbor's Toyota upstream lambda sensor and it was a piece of cake - it wasn't even threaded.

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All it had was two 12mm nuts holding it on and you just pull it out!

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This Mitsubishi "should" have been a piece of cake, but I'll learn by following your advice of using the chaser first, if there are enough threads left.

If the chaser fails, should I try to buy a M18x1.5 tap to be "more aggressive", or should I move on to the inserts?

Reply to
Arlen Holder

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:

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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.

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Reply to
Arlen Holder

I understand that a used exhaust manifold is problematic.

Worse, it appears that the catalytic converter is integral with the exhaust manifold on this vehicle, so, getting a "used" cat is problematic to start with.

Reply to
Arlen Holder

They are not even allowed to sell you a used converter - at least not here.

Reply to
Clare Snyder

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.

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:

Still, at least that "jb weld" or "epoxy" or whatever it was, seems to be cleaned out.

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.

Reply to
Arlen Holder

This is California, so, if there's anywhere on earth that you're not allowed to do something, it's gonna be in California for sure.

So that knocks out a used exhaust manifold from the equation.

BTW, I think I figured out WHY the ham-fisted person cross-threaded the old oxygen sensor.

The radiator upper hose is in the way of a straight shot, so I gently removed the upper radiator hose (which was rather loose with a hose clamp).

Then I was able to get a perfectly straight shot on the thread chaser:

Reply to
Arlen Holder

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:

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.

When it met a slight resistance, I used the crows foot, still by hand:

Then, when it bottomed, I gently applied leverage ever so slightly:

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:

And I buttoned back up the heat shield & routed the oxygen sensor wiring:

Reply to
Arlen Holder

Hi Clare, I had the teen run a short test (the car isn't street insured and the kid doesn't yet have his license so I had the kid test it on a bunch of private roads at 10 mph (if that) where it's legal to drive at least on private property - where all the neighbors have been prior warned).

There was some smoke around the exhaust manifold where we were working, and the car stalled a few times when it just about warmed up (so I presume the choke went off), but I am hoping that the mist of oily smoke is just the oil that got on the manifold when we removed the old lambda sensor.

Of course, the amber "Service Engine Soon" light was lit the whole time:

I cleared the SES light such that the SRS is the only remaining warning:

There are a few other anomalies I noticed, but the main question is how to test if the oxygen sensor is in tight enough.

Reply to
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 - - -

Reply to
Clare Snyder

First of all - it has NO CHOKE. The computer may have to "relearn" with the new sensor. Any finger prionts or penetrating oil etc on the manifold will make it smoke. Let it cool down and start it again. If it smokes a lot less, or not al all, you are good.

As for "tight enough" - if you could get 120 foot lbs out of it it's tight enough. Only takes about 10 to squash the washer.

I believe the torque spec is 33 ft lbs on a Mitsu. Many others are spec'd as finger tight (no movement) plus 1/4 turn - about 18-25 ft lbs.

Reply to
Clare Snyder

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).

Reply to
Arlen Holder

Thanks for that choke advice. It must have "some" mechanism of increasing the fuel-to-air to achieve the 14:1 stoichemotry when cold, so that's kind of sort of what I meant by choke.

Basically, it stalls at low speed (which is all we've been able to do) whenever it's transitioning from warm on the gauge (about 10 minutes or so of low-speed driving). It did this *before* the oxygen sensor, so it's unrelated to the sensor.

The OBDII tester gives us a 800 rpm reading at idle. Dunno how to increase the idle speed yet, as this car isn't mine (mine is a bimmer which is a drive by wire mechanism).

Thanks for that advice Clare, where you have always been spot on in accuracy. I'm gonna assume it's tight enough since I did get a good last

1/8th of a turn on it with a wrench, and where I can't think of how else to test it other than to see if the cleared codes come back under 10mph driving (which is all we can do at this time).

If that's the case, then I think the torque is fine.

The funny thing is I wonder why the mechanic who screwed it up didn't just do what I just did. What did he gain by jb welding it (or whatever that gray hard metal-like paste was)?

Reply to
Arlen Holder

Right. The error message you got about the sensor was ALSO unrelated to the sensor. The error message says the output of the sensor is out of range. It's out of range because the engine is running way too rich or way too lean.

You don't. You find the vacuum leak or the bad idle control valve or whatever it is that is causing the mixture to be all wrong, and then your idle speed will stabilize and you will be able to accelerate again.

--scott

Reply to
Scott Dorsey

He didn't have to replace the sensor he screwed up. He "salvaged" it and didn't have to tell the customer he screwed up - or it was A DIY job and he figured he wasn't going to spend money on "another shitty sensor" that likely wouldn't fit either - - - - - -

Always blame the part - don't take the blame for your mistakes - - -

Reply to
Clare Snyder

Or mabee it's not - - -

Or the sensor is bad - or the ground return (if used) is bad - a hundred and one things can turn on the CEL - and that code

What code was it displaying?????

That is possible - definitely check for leaks - but now at least he knows if the light comes on again he DOES have a problem. The sensor definitely needed to be fixed, either way.

800 RPM hot idle does not necessarily sound like a problem - and a bad sensor cannot get the computer to adjust the mixture properly.

Need to check the block learn readings etc to know for sure , but too rich or too lean should give rich or lean codes, not out of range codes. Out of range means voltage higher or lower than normal operating range, and generally static - not clocking. Too lean means violtage higher than optimum - too rich means voltage too low .

Too lean would generally be a P0171, or P0174. Too rich would be P0172 or P0175.

A bad sensor would generallly be a P0130 to P0170 - but other problems can cause these codes as well.

Reply to
Clare Snyder

That makes sense (from his standpoint).

The old sensor didn't look at that old, so, maybe it was his attempt to fix the code. Dunno.

I just think it was a crappy job that I'd be embarrassed to do if it were me.

I'm glad you pointed to the chaser - as - I think - it did the trick (cross my fingers).

Reply to
Arlen Holder

Unfortunately I don't remember the code. But it was related to the oxygen sensor, but I should have written it down. P0133 perhaps? I don't remember though. So I apologize not to be able to provide that fact to you.

The good news is that a new code, if it pops up, will tell me something since the sensor is new (and they don't last forever).

I agree. The 800 is fine as an idle speed. But it does stall. So, there's something wrong when it transitions from cold to warm. Dunno what yet. A cost-effective smoke machine is something I've always wanted ...

(I built one, but it sucks.)

As I recall, there were no misfire codes and no lean condition codes. Just the O2 code (might have been a cat code, I wish I remembered it.)

Yup. None of those. Since I own a bimmer that is almost two decades old, I know all about lean condition codes.

This code was cat or sensor specific. But let's see if it comes back.

Yup. Chasing codes is always fun. Not.

Reply to
Arlen Holder

Understood. The error is just an error in the input, output, or power of the sensor.

Always wanted to buy a good smoke tester at a good price that a home mechanic can make an argument for on cost/benefit analysis.

Reply to
Arlen Holder

There is also a code for the O2 sensor heater. That's the common failure on the BMW here. They don't work unless they are hot, so to get it working faster with a cold engine the sensors have heaters.

I've seen stories of people using disco smoke machines that you can buy on ebay.

Maybe it will be back soon. How old did that previous sensor look? Possible that there is another problem and it's not the sensor,so some hack changed it recently. Did anyone check out this car before buying it to make sure it wasn't a lost cause?

Reply to
trader_4

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