Post a photo of problem bolt.
Also always use silver-based anti-seize when working in these exhaust parts. Making the next removal much easier.

 

Here ya go.

 

The spring bolts are under a lot of tension.I ended up cutting them with a grinder. Get another spring kit from your local auto parts store....It only a few $$. There is a donut gasket where the front pipe connects to the exhaust manifold and is probably where you have an exhaust leak.Change this gasket also

 

If you even crack the bolts loose you need to replace all the gaskets you touched. I don't remember mine being oriented like that, odd. With those two o2 nuts off you can't sneak it out? Because I got mine off no problem. I also cracked those loose way back to run a tap and die on the stuff because I was getting neurotic about the rusted hardware on the car.

 

Oh great.. another gasket to replace! :surprise: I should of never replaced the o2 sensor to begin with because this is become a never-ending project.

With the o2 nuts off I cannot get the o2 out.. I have tried numerous times in as many ways as I can imagine. That spring bolt overlaps the sensor just enough that it seems to make it impossible. It doesn't seem like it would be designed that way.. so perhaps the bolt was tweaked at some point.

 

Here are a couple more pics in case they are helpful (taken with the heat shields off for a better view):

It also occurs to me that I may not be up to the task of replacing the spring bolts/front exhaust gasket. I'm really not a mechanic, have limited tools, and am wondering if I am reaching the limit of my abilities in doing this. The parts look cheap, and I can't imagine its that difficult.. but I haven't found any good videos or instructional guides of how to go about it which makes me nervous.

 

Update:

I think I discovered why the bolt won't unscrew all the way. It seems to be hitting the o2 sensor when its close to fully unscrewed.. hmm! So it appears I can't take out the bolt without first removing the o2 sensor, but I can't remove the o2 sensor without removing the bolt! It's a paradox.

Here is a pic of the bolt unscrewed as far as it can go:

 

Well how the heck did you get it all put together then? LOL!

The O2 sensor must come out first, you should be able to angle it and rotate it and get it to clear if you can get it off one stud on the exhaust.

 

As I mentioned in my original post; when I replaced the o2 sensor, the left stud got accidentally yanked out in the process which made it so I could rotate the sensor and easily remove the old sensor (since it was only being held in place by one stud). When I installed the new one, I first put the sensor in place and then inserted the new stud.

I have attempted to angle/rotate/jiggle/yank the sensor numerous times and it just won't come out. It gets hung up on that bolt and no matter what I do it refuses to come off. It seems like the obvious solution is to screw the bolt in a little more to allow clearance of the sensor, but I have tried over and over. It rotates freely until a certain point where it simply stops and will not go any further. I have sprayed it numerous times with PB blaster and that makes no difference.

I might try one more time if it stops raining.. but if that doesn't work I am about ready to give up and pay a mechanic to deal with it.

 

Ah, so just take the studs out! Loosen the nut a few turns, put a lock washer on top of the nut, put a nut on the stud so it's nut lock washer nut like a sandwich, then tighten the top nut against the lock washer and bottom nut. You may need to hold the bottom nut with a wrench. Then when you turn the top nut the whole stud with nuts will come out like a bolt. Reverse procedure to install the stud again.

 

Umm.. I think I am following you, but don't you mean "..when you turn the BOTTOM nut the whole stud with nuts will come out.."? And then to get the stud back in I would turn the TOP nut (clockwise) to put the stud back in?

Unfortunately I don't have any extra nuts or lock washers on hand, but I will take a trip to the hardware store this afternoon.

 

It's easier to turn the top one, it'll be jammed in against the washer and nut below it pretty hard and should pull the whole stud out, but you can try using the lower nut to crack it loose first. Most people skip the lock washer, it's not always needed. Usually there's enough friction between the two nuts.

 

Update

UPDATE:

Thanks to Bitter's advice, I managed to remove the stud and get the o2 sensor off! I looked closely at the gasket and I think I may of figured out why its leaking. There are a couple of tiny crimps in the metal that surrounds the gasket and I am thinking they might be creating a tiny hairline crack between the gasket and the pipe. Here is a photo that shows the new gasket (top) and the old funky gasket from the previous o2 sensor. I put little red arrows where the "crimps" are:

So now I have a couple questions:

1> Does it seem like I am correct in my guess that those tiny crimps are causing the leak? If so, I assume I need to get a new gasket?

2> Since I messed with the spring bolt that holds the front exhaust to the exhaust manifold, it was suggested that I should replace the donut gasket in that connection. Do I really need to do this? That sounds like a difficult project for my skill level and I don't really want to take it on unless its necessary. I only loosened one of the bolts, so I am thinking maybe its not really needed.

Thanks much,
Shawn

 

I'd be more suspicious of rust scale causing an uneven surface that the gasket is having a hard time sealing. You can try to scrape it clean and smooth and use a new graphite style gasket or put it together as is with a little muffler cement smeared on both sides. Also it may be supposed to go the other side facing the pipe.

 

It may need to go the other side facing the pipe? Well shoot.. how do I know for sure which side should go towards the pipe? I am pretty sure when I removed the old one that was the side that was pipe facing, so I assumed the new one would be the same. The instructions for the o2 sensor (Denso brand) don't say anything about which direction it should face. There also doesn't seem to be any consensus online regarding this topic. Hmm!

Anyone know for sure which direction the gasket should face?

 

It's a couple bucks for a new gasket, no reason to cheap out on something like that. A copper crush ring for your brake lines is one time use. Sometimes you can get away with reusing stuff like that. Like a crush ring for your oil drain bolt but there's no reason to do that to save 8 quarters. I would really be surprised if they were multi use.

 

I hear ya, but I can't find that exact gasket in any my local auto parts stores. The Toyota dealership can order it and have it here by tomorrow, but they are charging $18 for it which is kind of ridiculous. It seems like I could simply re-install it unless someone has a specific reason why I shouldn't. I get that some parts are not multi use, but what is it about this gasket that would make it stop working if I re-installed it?

Side Note; I finally got an "official" answer to which direction to mount the gasket. I spent an hour on the phone with Denso and after talking to 3 different tech people they finally agreed that it can be installed either way, but the best side to have facing the exhaust pipe is the one with more metal (the opposite side of the gasket in the photo I posted above).

 

The outside edge of the gasket doesn't matter with sealing, it's that central ring that does it. Sometimes, that ring is too small and isn't pinched between the flange and O2-sensor. Measure the ID of the hole in flange and compare to that ring in gasket. As Bitter mentioned, some sealant would help. I usually give them 2-3 layers of Coppercoat spray before installing.

Also, to what torque are you tightening those O2-sensor nuts to?

 

What torque am I tightening to? Haha.. you must be assuming I have a torque wrench. I have a basic ratchet set and that is it. I tightened it as tight as I could by hand..

I will check the hole sizes, and if I can manage to get to an auto parts store I will look at sealant possibilities. I assume this Permatex product is basically the same thing? http://www.oreillyauto.com/site/c/d...e/c/detail/PER0/80697/N2362.oap?ck=Search_N2362_1432910_3225&pt=N2362&ppt=C1984

*Edit: If I get the gasket sealer spray; how do I use it exactly? Spray on the gasket and install? Spray on both gasket and metal surface it goes against? Specific instructions would be great.

Thanks!

 

I've never had any issues with O2-sensor gaskets from auto-parts stores in my 35-years of working on cars. Most issues are due to user technique or specs (torque) than anything else. https://www.napaonline.com/en/p/NDP6001152

The Coppercoat sprays a soft layer of sealant onto the gasket's surface and allows it to fill surface irregularities. Ideally you want surface roughness RA=100 or finer on the flanges so that the gasket's surface matches both surfaces evenly. But that's only possible if you have access to flange and can sand it with a metal block. So sealant makes up for that difficulty. And copper metal content improves heat-dissipation across surfaces and doesn't burn off. Thus sealing can be maintained at high-temperatures.

For torquing down nuts, are you able to get a socket fully on those nuts? Be sure to use deep-drive socket, otherwise protruding end of stud will push the socket off and you won't be able to add sufficient torque. Be sure to alternate back & forth between two nuts several times while bringing torque up to spec (14 lb*ft with silver anti-seize on threads). Also use wobble/U-joint and as many extensions as needed. With sufficient extensions and wobbles, you can pretty much take entire engine apart while sitting in a lawn-chair in front of car.

 

The Coppercoat sprays a soft layer of sealant onto the gasket's surface and allows it to fill surface irregularities. Ideally you want surface roughness RA=100 or finer on the flanges so that the gasket's surface matches both surfaces evenly. But that's only possible if you have access to flange and can sand it with a metal block. So sealant makes up for that difficulty. And copper metal content improves heat-dissipation across surfaces and doesn't burn off. Thus sealing can be maintained at high-temperatures.

Got it. Thank you for explaining that.

For torquing down nuts, are you able to get a socket fully on those nuts? Be sure to use deep-drive socket, otherwise protruding end of stud will push the socket off and you won't be able to add sufficient torque. Be sure to alternate back & forth between two nuts several times while bringing torque up to spec (14 lb*ft with silver anti-seize on threads). Also use wobble/U-joint and as many extensions as needed. With sufficient extensions and wobbles, you can pretty much take entire engine apart while sitting in a lawn-chair in front of car.

I didn't understand half of what you said. As I said before, all I have is a very basic ratchet set.. no "wobbles" or extensions or torque wrenches. The socket is able to go fully on the nut. I have no idea what 14lb/ft translates to.. but from a brief search of the internet it seems something like "tight, but not too tight". So perhaps I over-tightened the nuts before, because I cranked them down as tight as I could get them with my socket wrench. I need to do this right now since another big rainstorm is approaching, so I am going to try finger-tightening the nuts and then use the socket wrench to get a bit tighter, but not too much.. hopefully that will be just about right.

Thanks for all the info!

 

14 ft lb is about 1/4 to 1/3 turn past limp wrist snug with the ratchet.

 

Issue Solved (Hopefully)

UPDATE:
I did everything recommended in this thread:
•*Lightly sanded exhaust flange with 400grit sandpaper and wiped down with cloth. It feels nice and smooth to my touch.
•*Purchased brand new OEM gasket from dealership.
•*Used copper hi-temp spray gasket sealant on the gasket as per DannoXYZ’s instructions.
•*Hand tightened nuts with socket wrench to be just past snug.

I tested it out and the leak was worse than before! Instead of leaking out of one small spot, it was coming out all around the gasket, as well as out the threads through the nuts. Arg!

I was just about to give up and go to a local mechanic, but figured I would make one more last ditch effort. I coated the previous gasket (the one that was leaking at the beginning of this thread) with the copper spray, and tried that one. I tightened the nuts a little more than before (quite snug, but not too extreme), and tested for leaks. No more leaks that I could see! So I think the issue is resolved.. and hopefully it will stay that way.

Thanks to everyone who gave advice in this thread. Much appreciated!

 

I was just about to give up and go to a local mechanic, but figured I would make one more last ditch effort. I coated the previous gasket (the one that was leaking at the beginning of this thread) with the copper spray, and tried that one. I tightened the nuts a little more than before (quite snug, but not too extreme), and tested for leaks. No more leaks that I could see! So I think the issue is resolved.. and hopefully it will stay that way.

Thanks to everyone who gave advice in this thread. Much appreciated!

Great perseverance and good job!!! :smile:
Especially given that you've never done this job before and have a limited set of tools, wow!
Congratulations!

 

The new gasket probably wasn't torqued enough. Its got a lot of air pressure trying to escape, right near the pressure source.

I don't want to be a nay sayer but those gaskets in a can are usually temp fixes for high pressure areas. I clean the threads up on mine and torque it down pretty tight, no over kill but tight enough. I'm not worried about it being easy to take off the next time. I'll wrestle with that when I get there but I do clean the threads up a bit when I take the stuff off. If I have to get it off again you can always break/cut the nut and grab two nuts/bolts whatever for a couple bucks. The spray might be able to seal it well enough for a long term fix tho.

 

The exhaust is high temp, not really high pressure. There's some pressure, maybe 3-5psi at full throttle at the most.

 

Yeah, NA engines have low exhaust pressure. I've had no issues with Coppercoat on turbo engines overdriving stock turbos by 150%. Imagine stock 10psi being bumped up to 25-30psi!! Exhaust-pressures go from sane 8psi to over 55-60psi!! That's double the intake boost!! Not a single leak from any exhaust gaskets.

Now if the gasket was gonna leak with the Coppercoat, it will also leak without, but even sooner. And Coppercoat is what Cometic recommends for their all-metal MLS headgaskets on extreme boost cars running 40psi++++. It is not a FIPG material that replaces the gasket, it's more of an adhesive or sealant that enhances an existing gasket.

Its primary function is to seal the surface scratches that channel under the metal-to-metal interface between metal-surfaces and compression-rings. Such as the central ring on O2-sensor or headgaskets. With rough surfaces Ra<80, these scratches are too fine for the compression-ring to deform into, but still large enough to seep out combustion-gases or coolant or exhaust-gases.

Gives you a little buffer, but does not make up for improper procedure or specs (torque).

 

You're welcome! Now that's you've been officially inducted into the home-mechanics guild, you'll need additional tools to make repair jobs easier and take less time. These wobble sockets with built-in U-joints can get into tight spaces.

You'll need torque-wrench: http://www.harborfreight.com/3-8-eighth-inch-drive-click-type-torque-wrench-807.html
Check out http://www.hfqpdb.com for HF coupons and free stuff!

 

Corolla 98, O2 Sensor - Upstream

I have the same problem. Can't get O2 sensor out because of exhaust bolt (through spring) blocks its extraction, even with both O2 nuts off. Can't tighten exhaust bolt to get it out of the way (no leverage). Design flaw if you ask me. Auto Mechanic Shop quoted me $250.

Remove two heat shields. I took a hacksaw blade and cut through exhaust flange bolt. By placing the blade through gap in spring (pic). The other bolt removes easily from underneath. Removed bad O2 sensor. Bought shorter bolt M10-1.25X50MM. Cut off 25% of one spring. The new bolt does not have end of travel for threads (pic), so use mirror and make the spring compression look like the other side. It is not all the way tight. Then screw a flange nut M10-1.25 on top of the new bolt to keep it in place, no washer. Now you have clearance to install the new O2 sensor. Put shields back on.

 

I have the same problem. Can't get O2 sensor out because of exhaust bolt (through spring) blocks its extraction, even with both O2 nuts off. Can't tighten exhaust bolt to get it out of the way (no leverage). Design flaw if you ask me.

I just addressed this in my revived, eternal spark plug thread. I guess whether we have to fight to get past that bolt depends on how far ours has been screwed in. I eventually was able to pry the base plate of the original, defective OS2 unit under and past the overhanding, obstructing bolt with a huge screwdriver. I'd go back and forth between the right, or rear, top edge of the OS2 plate and just catch it under the edge of that bolt head, and then go to the front, or left, edge, and maybe work it a hundredth of an inch at a time, but if your overhead bolt is a turn further out than mine was, maybe it would not be doable for you.


After I had forcibly removed the original, malfunctioning OS2 sensor, I crawled under the vehicle and used maybe a foot of extension and an 18" breaker bar to try to tighten the obstructing bolt to better allow me to install the replacement OS2, but couldn't crack it, though I didn't force it to the physical max because I didn't want to risk breaking it. I was not able to heat it with my torch because the flame kept going out at that upside down angle.

As far as whether the unified construction of the original OS2 sensor should be regarded as a design problem in concerned, I'd say the fact that they redesigned the replacement unit so that the sensor can be unscrewed from the plate is an acknowledgement that their design was bad. I'm sure that when they manufactured the car, they attached the OS2 plate before the engine was dropped into the car, and that they also installed that obstructing, overhead bolt while working out in the open, where they could still put an open end wrench on it.

The real hard part, after you do succeed at prying the old OS2 sensor out, is there is no corresponding way to pry the replacement one in, even though you will have first unscrewed the new sensor from its plate, but as I explained in the other thread, I "cheated" and cut a channel into the new unit's mounting plate that let me slide the plate just onto the left, or front stud, push it back, and then swing or pivot it up onto the right or rear bolt..

 

I have had this problem and found an easy and effective solution. I am posting it here in the hopes that it will help someone. Place a jack under the car so that it makes contact with the place where the transaxle bolts to the engine. Lift the engine up until you have enough clearance to get the O2 sensor out.

It works.

 

I have found an easy and effective solution to this problem.
Place a jack under the car so that it contacts the place where the transaxle bolts onto the engine. Lift the engine up until you have enough clearance to get the sensor off. It works.

 

ShadeTree,

Thanks so much for posting this trick. I had the same issue and was starting to get overwhelmed thinking about the challenges if the studs and flange bolt. This was a super easy and effective way to get the sensor out. Your 5 minutes to post saved me hours!