All O2 sensors are subject to an instant death from silicone. While there are alledgedly O2 safe sealants, I've still managed to kill and O2 after engine work.

So my current strategy is just running the engine 200 miles are so after engine work to make sure there is no silicone or even traces of it in the system, without an O2.

Maybe obvious, but just thought I'd say it.

Now we're just left to ponder is this my idea or a friend's that I'm PD'ing. Or does it matter?.

 

Question, why is there silicone in your engine?

I can see maybe you're saying that the RTV sealants emit a little that may seep into the combustion chambers somehow... I dunno

 

It may hard to believe (I didn't at one time) but silicone takes out O2's so quick it is unbelievable. What happens is that the silicone molecules fill in the spaces of the porous 'cone'. This is turn causes the sensor to become slow, then become non-responsive.

There is a SAE article written by GM (wish I could find it) that goes into detail about what they found. GM vehicles don't even use silicon jacketed spark plug wires any more. That is why.

What happened to me was that I dumped an empty tube of RTV caulk (house work) into the garage trash. Two days later the O2 went bad in the car parked in the garage. White fluff all over it.

RBob.

 

Just using an aerosol with silicone in, the the garage, it can kill an O2. Engine doesn't even have to be running. Just what's in the air an hour later.

 

An O2 sensor has 2 electrodes. One electrode is in the exhaust stream, the other is ported to outside air thru a small hole in the outer case. Some antifreezes will also poison a sensor if gets inside the port.

 

Exactly my reaction! I had no idea this was the case, but now I'll make sure to be more careful with my sealants!

 

Silicone in the air moves VERY VERY quickly. I can attest to that. I was once at our dealership a few years ago where they were painting a truck, worker there using the facility. I had my Grand Cherokee there and was using a little silicone lub to cure a squeeky hinge. They were about 20 ft away in a plastic draped room and the minute I sprayed that stuff, and at the same time they were painting. They started screaming. The result was huge "fish eyes" in the paint where the silicone dispersed the paint.

So I can see that the stuff could easily get into the sensors and ruin something very easily, even if not intentially sprayed near an intake or 02.

 

Will the O2 sensor recover? I used some silicon lubricant a while back to try to get my throttle body to stop sticking (turned out to be a mechanical interferance with my cruise control cable). I didn't realize at the time that silicon killed O2 sensors.

I have been running my carburetor for a while now, and thought I was running rich (mixture gauge showing rich). I even tried some leaner jets for a while because of it. The spark plugs now show the mixture to be pretty close to right.

My sensor has been measuring rich for quite a while, but has recently started reporting leaner and leaner condition. It now looks like it is about right.

Or, maybe it is just my imagination.

 

Nope, they're poisioned.
While it might clean up enough to develope some readings, I wouldn't count on it.
I've also just flipped to open loop and in 300 miles they remain dead.

 

I dunno what else to say. That is absolutely crazy. Why in the hell would GM ever produce a part that was THAT sensitive! I mean, I knew that these things went bad if you sneezed in the wrong direction, but DAMN! That's just ridiculous. So is it a bad thing to even use silicone spray on the door hinges? I can't count how many times I've done that in the past month! What's in the stuff that makes it do that? Does this mean I can't use Super Blue II to make my thermostat gaskets anymore?

 

When you create an agency like the EPA that is responsible to no one, and has no over sight, this is the type of nonsense they mandate. And just think, in order to justify their existence, they will continue to generate short term narrow minded solutions.

 

Grumpy,

I think for once we see eye to eye on a subject. I couldn't have said it better! :cheers: