Was talking with Permatex Tech yesterday asking about their copper RTV. The subject of anti-seize came up and he said anti-seize was an excellent thread sealer. I had never heard that so I searched the internet. Could not find any reference which said anti-seize seals threads. Was the Permatex Tech full of bull? Will anti-seize seal O2 sensor threads against an exhaust leak? Thanks.
Anti-Seize
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New O2 sensors come with a stripe of some kind of anti seize. I would not add anything.I never had a leak at the sensor. Reason, the ground connection for the O2 sensor is often made thru the threaded body of the sensor. Putting too much will drive the PCM crazy with erratic readings.
There are thread sealers and there are anti seize compounds.I think the rep is misguided.
There are thread sealers and there are anti seize compounds.I think the rep is misguided.
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I would figure AS would seal threads about as well as using grease. Not at the same level as thread dope or teflon tape but a lot better than nothing. Would not be what I used on plumbing or the like, though unless you have some type of damage to the bung I can't see how AS would result in an exhaust leak at the o2 sensor.
As mentioned above, don't depend on anti-seize as a thread sealant. It works very well as its intended purpose, which is to prevent your threads from getting torn up. By the way, I prefer the silver Permatex stuff.
I did use anti-seize (supplied by Denso) on the sensor threads but used a little RTV on the sensor crush washer because the boss was slightly scarred from a difficult removal of the old sensor.
Originally Posted By: Merkava_4
As mentioned above, don't depend on anti-seize as a thread sealant. It works very well as its intended purpose, which is to prevent your threads from getting torn up. By the way, I prefer the silver Permatex stuff.
Right, none of the Permatex anti-seize spec sheets make any claims regarding thread sealing.
As mentioned above, don't depend on anti-seize as a thread sealant. It works very well as its intended purpose, which is to prevent your threads from getting torn up. By the way, I prefer the silver Permatex stuff.
Right, none of the Permatex anti-seize spec sheets make any claims regarding thread sealing.
Originally Posted By: artbuc
I did use anti-seize (supplied by Denso) on the sensor threads but used a little RTV on the sensor crush washer because the boss was slightly scarred from a difficult removal of the old sensor.
'Difficult removal of the old sensor' is exactly the reason why the new one came with anti-seize on the threads. The RTV you applied is doing nothing.
I did use anti-seize (supplied by Denso) on the sensor threads but used a little RTV on the sensor crush washer because the boss was slightly scarred from a difficult removal of the old sensor.
'Difficult removal of the old sensor' is exactly the reason why the new one came with anti-seize on the threads. The RTV you applied is doing nothing.
Originally Posted By: Bottom_Feeder
Originally Posted By: artbuc
I did use anti-seize (supplied by Denso) on the sensor threads but used a little RTV on the sensor crush washer because the boss was slightly scarred from a difficult removal of the old sensor.
'Difficult removal of the old sensor' is exactly the reason why the new one came with anti-seize on the threads. The RTV you applied is doing nothing.
How do you know the RTV is doing nothing? I applied AS to the threads only. The RTV is external to the threads between the boss and sensor crush washer. There is a nice fillet of RTV between sensor and boss. Most of the RTV squeezed out hopefully leaving only whatever it took to fill the small gouges. The only reason it is not doing anything would be if the crush washer was able to seal against the slightly damaged boss and squeezed out all of the RTV.
Originally Posted By: artbuc
I did use anti-seize (supplied by Denso) on the sensor threads but used a little RTV on the sensor crush washer because the boss was slightly scarred from a difficult removal of the old sensor.
'Difficult removal of the old sensor' is exactly the reason why the new one came with anti-seize on the threads. The RTV you applied is doing nothing.
How do you know the RTV is doing nothing? I applied AS to the threads only. The RTV is external to the threads between the boss and sensor crush washer. There is a nice fillet of RTV between sensor and boss. Most of the RTV squeezed out hopefully leaving only whatever it took to fill the small gouges. The only reason it is not doing anything would be if the crush washer was able to seal against the slightly damaged boss and squeezed out all of the RTV.
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Originally Posted By: cptbarkey
I doubt the RTV would like 700 degrees of temperature anyway.
I don't have an IR temp probe, but the external metal temp where the boss mates with the sensor would be substantially below 700, at least that is what the Permatx guy said. He claims they do a lot of testing to validate the use of copper RTV on exhaust manifolds/systems.
I doubt the RTV would like 700 degrees of temperature anyway.
I don't have an IR temp probe, but the external metal temp where the boss mates with the sensor would be substantially below 700, at least that is what the Permatx guy said. He claims they do a lot of testing to validate the use of copper RTV on exhaust manifolds/systems.
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I hope the RTV used was sensor safe or you could have shortened the life of the sensor if you applied too much. Personally, I can't see RTV handing the temperature and likely did nothing for you.If you did have a leak, the exhaust pressure would blow out that RTV.
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Originally Posted By: Lubener
I hope the RTV used was sensor safe or you could have shortened the life of the sensor if you applied too much. Personally, I can't see RTV handing the temperature and likely did nothing for you.If you did have a leak, the exhaust pressure would blow out that RTV.
It is sensor safe but I was very careful to not get a spec of RTV or AS near the business end. You may be right about the RTV. I have no way of knowing. Did a whole lot of research and it looks like 70-80% say copper RTV is useless in exhaust systems and 20-30% say it works great. Wonder how Permatex gets away with claiming it is great for exhaust manifolds. Afterall, its max intermittent temp rating is only 50 degrees higher than their red stuff and the continuous temp rating is the same.
I hope the RTV used was sensor safe or you could have shortened the life of the sensor if you applied too much. Personally, I can't see RTV handing the temperature and likely did nothing for you.If you did have a leak, the exhaust pressure would blow out that RTV.
It is sensor safe but I was very careful to not get a spec of RTV or AS near the business end. You may be right about the RTV. I have no way of knowing. Did a whole lot of research and it looks like 70-80% say copper RTV is useless in exhaust systems and 20-30% say it works great. Wonder how Permatex gets away with claiming it is great for exhaust manifolds. Afterall, its max intermittent temp rating is only 50 degrees higher than their red stuff and the continuous temp rating is the same.
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You shouldn't be adding RTV to the mating surface between the O2 sensor gasket seal and the manifold.
2 reasons: (1) RTV silicone is not designed to handle such high heat coming from manifold w/o disintegrating, and (2) just like spark plug thread base (be it taper or gasket type), typically sealed by means of smooth, clean and grease-free form and proper torquing of the threads (in both spark plugs and O2 sensors case). Corrosion, pitting and damaged mating surface on either the manifold side or spark plug thread base side, then you must fix those issues first before installing O2 sensor.
Just like spark plugs on IC engines: manufacturing process + engineering know-how has been perfected in this case for many, many decades now, so spark plug mating to the engine block is to be uphold, gas-tight by means of either taper spark plug seat; or with a spark plug base gasket to engine block.
Don't overthink things, my friend, for it will not do you any good.
Q.
2 reasons: (1) RTV silicone is not designed to handle such high heat coming from manifold w/o disintegrating, and (2) just like spark plug thread base (be it taper or gasket type), typically sealed by means of smooth, clean and grease-free form and proper torquing of the threads (in both spark plugs and O2 sensors case). Corrosion, pitting and damaged mating surface on either the manifold side or spark plug thread base side, then you must fix those issues first before installing O2 sensor.
Just like spark plugs on IC engines: manufacturing process + engineering know-how has been perfected in this case for many, many decades now, so spark plug mating to the engine block is to be uphold, gas-tight by means of either taper spark plug seat; or with a spark plug base gasket to engine block.
Don't overthink things, my friend, for it will not do you any good.
Q.
Originally Posted By: Quest
You shouldn't be adding RTV to the mating surface between the O2 sensor gasket seal and the manifold.
2 reasons: (1) RTV silicone is not designed to handle such high heat coming from manifold w/o disintegrating, and (2) just like spark plug thread base (be it taper or gasket type), typically sealed by means of smooth, clean and grease-free form and proper torquing of the threads (in both spark plugs and O2 sensors case). Corrosion, pitting and damaged mating surface on either the manifold side or spark plug thread base side, then you must fix those issues first before installing O2 sensor.
Just like spark plugs on IC engines: manufacturing process + engineering know-how has been perfected in this case for many, many decades now, so spark plug mating to the engine block is to be uphold, gas-tight by means of either taper spark plug seat; or with a spark plug base gasket to engine block.
Don't overthink things, my friend, for it will not do you any good.
Q.
Thanks Q. What's done is done. If/when the RTV degrades, the sensor will either leak or not. For now, all is well. Still do not understand how Permatex gets away with listing exhaust manifolds as an application for their Ultra Copper RTV.
You shouldn't be adding RTV to the mating surface between the O2 sensor gasket seal and the manifold.
2 reasons: (1) RTV silicone is not designed to handle such high heat coming from manifold w/o disintegrating, and (2) just like spark plug thread base (be it taper or gasket type), typically sealed by means of smooth, clean and grease-free form and proper torquing of the threads (in both spark plugs and O2 sensors case). Corrosion, pitting and damaged mating surface on either the manifold side or spark plug thread base side, then you must fix those issues first before installing O2 sensor.
Just like spark plugs on IC engines: manufacturing process + engineering know-how has been perfected in this case for many, many decades now, so spark plug mating to the engine block is to be uphold, gas-tight by means of either taper spark plug seat; or with a spark plug base gasket to engine block.
Don't overthink things, my friend, for it will not do you any good.
Q.
Thanks Q. What's done is done. If/when the RTV degrades, the sensor will either leak or not. For now, all is well. Still do not understand how Permatex gets away with listing exhaust manifolds as an application for their Ultra Copper RTV.
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