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NISSAN SLAP NUTS
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1,051 Posts
Discussion Starter · #1 ·
I noticed that there was smoking(exhaust leak?) around the edge of the header where the o2 sender was screwed in.

Now the question is if it's tight ,what would cause this?
And is this bad? the ses or check light is not on.

thx.
 

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Powered By hopes & dreams
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8,328 Posts
it's possible there could be a crack, yes. I'd be wary of using a thermal sealant on the O2 sensor because you could get some on the sensor itself and damage it. Maybe have a shop run a couple weld beads around the bung....go from there.
 

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DO NOT put thread sealant on the sensor threads. RTV sealant won't stand up to the temperatures and if anti-sieze gets onto the sensor, it's done for. Also, I believe our cars use a 3-wire sensor meaning that it grounds through the headers. Any type of sealant would act as an insulator causing the PCM to see a low voltage and run a richer mixture. (=Bad mileage.) It is possible that the ceramic core in the O2S is cracked and causing a leak.

Oh, and make sure you demand that the shop disconnects the O2S before they weld near it. Mufflers For Less :thumbdwn: (bunch of freaking a-holes) fried my post-cat O2S by MIG welding within 2 inches of it.
 

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My header smoked very slightly when I first installed it because it was burning off some of the WD-40 I sprayed when losening the bolts. It stopped after a couple of days.
If your header is newly installed and the smoking is very mild, it may just be cooking off some material in the first couple of uses.
 

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My ass, your face
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if you just installed an o2 sensor and not a header...make sure you didnt cross-thread the sensor on. that would cause it to leak. try this..start the car and let it idle, then pop the hood and with one hand, pull the throttle cable to revv the motor....put your other hand around the o2 sensor and see if you can "feel" it leaking air....but you have to be careful not to cut urself up on the fans and not to touch the header/manifold!!
 
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