Anybody know what size nuts are used on the 02 sensor on a 99 4runner? Thanks

 

Turns out Google had the answer. For those of you interested, They are 8mm width x 1.25mm thread pitch.

 

Just a FYI, I went to the dealer to get a couple of those nuts and they wanted over 20 Bucks for 4, I looked at the guy and said are you kidding me, he said its because they are the special heat resistant ones, I said oh, is that why I had to use visegrips to get the old corroded ones off. I ended up getting 4 normal nuts for 2 bucks, its been over a year and they are still on.

 

I paid 50 cents for two nuts and two washers yesterday. When you have to replace the O2 in another 10 years, the nuts will be screwed no matter what you put on.

 

They should cost about $1.20 each here: http://www.trademotion.com/partlocat...?siteid=214074

 

Didnt want to start a new thread for this question.
What is the best way to mount an O2 sensor in an exhaust without an O2 bung? Can you buy and get the bung welded in? Can you just drill 3 holes and mounting it flush to the outside of the exhaust?

 

You will have to weld a bung on. The metal is not thick enough to simply drill into. It also needs to be a flat surface to mount to.

 

Some duct tape and bailing wire, maybe a couple zipties will hold it on perfectly.

 

I tried zip ties but they melted and the sensor fell out. I thought they'd be ok because I'd just topped off the muffler bearing lube reservoir and thought it would stay cooler than it did.

Should I get a muffler bearing lube cooler?

 

I couldn't find anyone that sells a Toyota O2 sensor bung to weld into my new exhaust piping. After talking to a friend that works at the local Toyota dealer about where to get one, he says why don't you just make one? I hadn't thought of that Jason, thanks for the idea. So here's how to make your own O2 sensor bung.
I started with a piece of 3/8 steel and marked the outline with a gasket and drilled and tapped some holes (8mm x 1.25):



I used some exhaust studs from the dealer that were left over when I was putting on the ORS cross-over.



Then I started cutting it out with a cutoff wheel on an angle grinder:




After using a grinder and beltsander to smooth it out:



Now that was one bung, but I need two for the 5VZ right. The first one took me about 2-3 hours to make so I decided to try cutting an old one out of my old 3.0 exhaust pipe and using it. That took about 2-3 hours too, counting replacing the old studs and smoothing it out with a grinder and beltsander too.

Here's the two side by side, the one I made from scratch will have to be welded in parallel to the pipe since it's not curved to the shape of the pipe:

 

O2 sensor question -

When they go bad do they generally only show a code, or could they go bad and show nothing?

I am still fighting a warm start issue and dont know if this is another area I should look into.