Many of the west coast people already heard about this, but I thought I'd share with the group. I installed my new brakes and y-pipe this weekend. The y-pipe was the budget exhaust SS mandrel bent one. I had the fortunate luxury of doing the install while my car was on a friends lift. The install went really fairly easy until the last step, plugging the O2 sensors into the new pipe.

The threads on the Nissan O2 sensors are weak, at least on my car, and were prone to bending. Also, I failed to check the threads carefully on the inside of the y-pipe itself. It turns out that they were slightly dirty with little sand like rocks, and also some of the black paint they used to coat the pipe somehow found its way into the threads. Also, the threads on my pipe were kinda soft like the O2 sensors and prone to getting screwed up. Not as soft as the O2 sensor, but still not super strong.
All this lead to a mini-crisis. I went to screw in the O2 sensors. The rear one grabed the pipe with some difficulty, but I was able to somewhat hand-tighten it. The front one was nothing but trouble and eventually popped out with a completely messed up thread. With no other O2 sensor in sight, at 4am I decided to leave the car on the lift overnight and try again tomarrow.

The next day we salvaged both the front O2 sensor and the pipe. My friend filed down some of the nasty thread edges on the O2 sensor and then pried them back with a screw driver head and pick. Then we went at both the pipe and the sensor with a dremel sanding bit in hopes that we could get everything flat and somewhat evenly spaced. Once we were somewhat satisfied that this had worked, we plugged the O2 sensor back into the old pipe to see if it would be a problem. When it seemed to fit, we coated everything with antisieze and plugged it back in to the new pipe, placed the pipe on the car, and I was in business.

Moral of the story, check the threads on your y-pipe and clean them before you try to plug in your O2 sensor. And be slow and gentle with the O2 sensor because of the weak metal.

 

In addition, while my car was on the lift, I took the opportunity to take some detailed pictures of the y-pipe setup for those that plan to do it in the future. Things are hard to grasp when they are directly in front of your face (ie, when the car is on jack stands). Check out (primarily) page 2 of my photo set:
http://hakker.org/gallery/maxinstall0303

 

dude try to delete the other 4 "extra" threads.

 

your undercarraige is VERY clean

 

i think the moral of the story is....


if your not sure what your doing, have Matthel install it for you!!

haha, anyways, yea debris in the threads causes some probs, but i have NEVER heard or seen debris cause the threads to strip. their not THAT soft of metal.

 

Metal was soft enough that we were able to bend the threads back with a screw driver. That's pretty soft. And sorry I didn't have you do it, but I needed to get my hands dirty and learn some about my car. Get some self respect as a car enthusiast Next time matt..

 

You shouldn't use anti-seize on the O2 sensors. All O2 sensor install instructions never tell you too, and most tell you not too. Why? Because most O2 sensors ground to the pipe.

Just make sure threads are clean, and don't overtorque.

 

1) o2 Sensors have a ground wire attached to them.

2) anti-seize would not stop the threads from conducting with the pipe.

 

That's what I thought. But according O2 sensor install instructions from Bosch, that's what it says.

Also, be VERY careful to keep the probe portion clean of the anti-seize. Most O2 sensor failures are caused by contamination (from dirty fuel, mmt, sulphur, carbon, oil, etc).

 

Yup, I agree. Keep the anti-seize off the sensor, and also, while you have em out, do Nigel's trick and give them a little brake cleaner. Works great.

 

I'm pretty sure I was the first person to mention that on the org. Brake cleaner works, although it's also a good idea to use a torch on them. Just a regular propane. Get the probe glowing hot, let it cool, then spray with cleaner, do this two step one more time. If your O2 failed from contamination, it should be working just fine after that.

 

anti sieze also has some components in it that will ruin the O2 sensor when the stuff gets hot and starts cooking off..

Maky sure any anti sieze you put on the O2 sensor is "O2 sensor safe".. it'll usually say on the side of the container.

 

damn chicago weather...my car is a 97 too and the undercarriage looks 10x more rusted

 

yea that is pretty soft, but i still feel that isnt an excuse for stripping the threads or the sensor. I work with that same "soft metal" all the time never stripped 1 O2 sensor or thread. (knock on wood)

yea, the 02 sensor safe antiseize should be ok. WHen you buy Nissan 02 sensors they come from the factory with antiseize.