Ceramic coating extractors and O2 sensor grounding?

**MacroP** · 27-02-2006, 06:15 PM

Just about to send my two headers away for HPC coating and was wondering if if I needed to weld an earthing stud on each of them, to get a good earthing point(to chassis or engine block) for the oxygen sensors.

I'm thinking, that the coating would not be very electrically conductive seeing as it's not heat conductive, so I may need to re-thread the sensor bungs/nuts back out when I get them back and earth the extractors somehow.

Anyone had a similar experience with this. Cheers.

mic* · 27-02-2006, 07:28 PM

Find a bolt with the same thread pattern and thread it almost through the manifold before you send it away.

Then you've got a clean earth as soon as you get it back and pull the dummy bolts out...

**Cool1** · 27-02-2006, 07:35 PM

I would doubt very much they will coat the face of the extractors!

**oldcorollas** · 27-02-2006, 08:51 PM

easy.. use a 2 or 4 wire O2 sensor

or you could scrape off the coating at one of the bolting points, and also the thread for the O2.. although it may be difficult to scrape off..

sensor earthed by wire is by far the best bet (and better anyway)

**thechuckster** · 28-02-2006, 12:47 AM

i think putting coating on the sensor bung threads would be pretty stupid - the coating place should be smart enough to not do that bit, nor the flange face. If they do, send it back.

**CrUZida** · 28-02-2006, 01:26 AM

Nope, whole extractors are coated.
Inside and out, all faces, everything, including o2 sensor hole.

Not having the car here, and not having the extractors back on I can't tell you if my o2 sensor still works.

But being an alloy coating, I can tell you it conducts.

**thechuckster** · 28-02-2006, 01:52 AM

ah ... i was assuming it was HPC high-temp ceramic coating - which i thought was not a good electrical conductor.

query: would there be issues with the gasket not bonding with the flange? or are we talking non-turbo here and not having the high pressure inside hte manofold?

**45aken** · 28-02-2006, 11:03 AM

just sand/grind down the flange that the sensor sits on (if it can be grounded through the base of the sensor)

**CrUZida** · 28-02-2006, 11:24 AM

Non turbo, and I'm presume Marco is going with the bling HPC, and not the black HPC, but I could be wrong.

**MacroP** · 28-02-2006, 06:19 PM

I was planning on the higher rated black coating. The headers aren't really visible from the engine bay so no one would see them. What I'm going to do is put a bung in the O2 socket and weld a 20mm M6 stud near the end of the headers so I can run a short earth wire across to the transmission casing