O2 Sensor / Lower Valve Cover

[400orbust]

Hi all. I'm attempting to adjust the valves on my new to me 1988 911 and on the driver's side lower valve cover there is what I assume to be the O2 sensor in the way of being able to remove the cover. The heat exchanger is an SSI. What am I missing here? Please don't tell me I have to drop the exhaust to remove the cover! See pic.

[fanaudical]

I would think you could pull the heat shield off the O2 sensor, disconnect the wiring, and remove the O2 sensor before tackling the valve cover...

[Techno Duck]

Why not just remove the O2 sensor? It should take all of 30 seconds.

[400orbust]

I guess if it can be removed easily...is that tack welded on shield part of the sensor that will come off?

[Big Dav]

The heat shield just has a clip which grips the body of the sensor. It will just pull off without too much grief. Unscrew the sensor from the exhaust bung and you should be home and hosed.

[911pcars]

What is the source for that heat shield? I assume it's not a tight seal so it traps splashed liquid?

[400orbust]

Ok...so to help anyone else who may have this problem:
The heat shield does just pull off, it was surprisingly tight (thanks Big Dav)
My O2 sensor was "welded" in there. I tried penetrating oil, heat, oil, heat, big wrench more oil and heat. Nothing budged it and the wrench was starting to round the corners off so I took an autobody air saw and cut the top off so I could put a 6pt socket on there. It finally came off with a big cheater and the threads are kinda messed up. I hope I can chase the bung in the exhaust with a tap.

[400orbust]

911pcars...the shield does not trap water. I assume it came with the SSI system. I just bought the car so don't know for sure.

[400orbust]

Oh and one more thing...the sensor is a 22 millimeter...took me 2 trips to the tool store to figure that out.

[911pcars]

Sensor bung is probably stainless. Sensor threads are either steel or stainless. In that under-car environment, they become one.

[Walt Fricke]

I've had O2 sensors seize up on me, too. Messed up the threads on the bung, so I switched to a plugged one I had on the other bank. I now use anti-seize on them, being careful not to get any beyond the threads of the sensor.

If the threads on the bung are buggered beyond reuse, you might consider welding that bung shut, drilling a hole at a better angle (but not downward), and welding in a new bung.

[chrismorse]

Would copper or nickel based anti-seize be appropriate??

I'm about to do a SSI and O2 sensor/megasquirt install.
chris

[chrismorse]

Originally Posted by Walt Fricke

I've had O2 sensors seize up on me, too. Messed up the threads on the bung, so I switched to a plugged one I had on the other bank. I now use anti-seize on them, being careful not to get any beyond the threads of the sensor.

If the threads on the bung are buggered beyond reuse, you might consider welding that bung shut, drilling a hole at a better angle (but not downward), and welding in a new bung.

Hi Walt,

I thought it was supposed to not be upward or horizontal, but at a slight downward angle - maybe 45 degrees??
chris

[Hotshot]

I just did this job. Take the pipe off. It’s easier. I use the Stomski tool and had to free up space to get the tool on the studs.

What I also found was I had an exhaust leak, I never saw. So, one thing lead to another. The cross piece needed Mag induction heater and an air hammer, but I got the orig bolts off.

A bit of a pain but a while your there moment.

Covers are blasted and getting Cerakoted

[HaroldMHedge]

Originally Posted by chrismorse

Would copper or nickel based anti-seize be appropriate??

I'm about to do a SSI and O2 sensor/megasquirt install.
chris

Since the SSI's are made from stainless steel, nickel anti-seize would be better than copper anti-seize.

[dg567]

O2 Sensor Shield PN 91160613300

available from our host:

https://www.pelicanparts.com/More_Info/91160613300OEM.htm?pn=911-606-133-00-OEM&bt=Y&fs=0&SVSVSI=5876

[Walt Fricke]

The O2 sensor can be installed anywhere that fits in the top 180 degrees of the tube. Being more vertical seems to be preferred as opposed to closer to the horizontal, but I don't think it matters. The reason not to install from the bottom is the chance of condensation settling into the sensor after you turn the engine off. Usually you can get a little up angle and still not have this hassle with the valve covers.

[400orbust]

Good news! I was able to get a tap in there to chase the threads with the pipes still on the car. It appeared that the metal for the sensor was softer than the stainless and it galled up inside threads. It took me some fussing but with dental type picks and a mirror I was able to clean out the top threads, then I put a torch on the bung to expand it a bit and was finally able to start the tap. The tap is and 18x1.5. I am so thankful I was able to fix this without too much fuss. Please use never-seize...someone with thank you later!
(got my shiny new rennline covers on too, hopefully they'll keep some oil where it is supposed to be)

[proporsche]

somehow i think the guilt of the oil leak is not the original Porsche valve covers;-)

Ivan

[Canada Kev]

Glad you got your O2 sensor challenge tackled. I hate working with exhaust system frozen hardware, but it looks like you got it sorted out.

You know you can get valve cover gasket sets that come with new nuts, right?

Yes, there are some here that claim they aren't required, and for the most part that's probably accurate. But for nuts that aren't torqued very tightly and on a part of the engine that's notorious for oil leaks, they add to one's peace of mind. Especially for how little extra they cost when included with a gasket kit.

And with your shiny new valve covers? Yeah, I think that's a pretty easy call to make.


Again, good work with the sensor and getting the bung fixed up. Those are often nasty jobs. I'm not looking forward to replacing those on my daily appliance which has four of them. I just look at the parts sitting in the garage and find another reason to procrastinate a little more...