Silicone spraying on hoses: safe for O2 sensors??

[kilou]

Hi,

not sure this is the right section for this post but it somewhat concerns cleaning.

I usually use silicone sprays to clean and lubricate most smooth plastic parts like hoses, ducts etc in the engine bay so that they remain smooth overtime. This has worked very well but I just read on this section that silicone can kill O2 sensors and catalyst very quickly! Of course I only use that silicone spray on the outside of the ducts, air intake hose etc but I wonder if vapors could go in the intake system when the engine is hot and be sucked with air intake possibly damaging the sensors etc!! Do you think it's a safe practice to lubricate smooth plastics in the engine bay with silicone spray???????

Thanks

 

[Quest]

While there is no definitive agreements RE: silicone spray will cause rubber deterioriation, or not (I tend to lean on the possibility of the "carrier agent" itself causing this problem), it would be to your best interest not to "overdo" things to your engine.

In other words: while cosmetically "dressing" your hoses, plastics inside your engine bay area theoretically shouldn't cause lead to any issues to your engine itself, personally, I would simply resort to the maintenance of basic cleanliness: e.g. no oil leaks, generally dust-free, etc. You are more than welcome to use engine degreaser to clean things up a little bit on a regular basis bit so long as (a) you do not leave any oil or oil substances (leaks, cleaners, solvents, etc.) on rubber hoses, ducts, etc. they will lasts a long, long time.

I think sprays like armourall or similar shouldn't create enough fumes to cause engine/O2 sensor issues but one can never be certain when someone "overdid" it (e.g. spraying armourall while engine is running/idling, accidental introduction of silicone spray into the engine intake part for no apparent reasons, etc.)

my 2 c's worth

 

[kilou]

I've done this silicone spraying since day 1 and the car is 9 years old now with no particular problem. I don't do that for cosmetic but rather to maintain the hoses crack-free and it seems the hoses are like new.

I know that some silicone sprays can deteriorate some plastics but usually it's written on the can when it does so (but I should remain careful of course). However mine especially mention that it is useful to maintain rubber parts or for lubrication purposes. It is not the one I use but this one also mention "helps prevent rubber cracking and drying"
http://www.amsoil.com/storefront/als.aspx

The problem of rubber deterioration should therefore not come from the silicone itself but from another component (like you said maybe the carrier). I remember having seen silicone sprays that warned they would destroy some king of plastic (polyethylen if I remember well)....

I have never and would never spray silicone while engine is running, I only do that when the engine is cold.

However I'll strongly limit this now since as you said it may be dangerous.....but that's too bad: all rubbers in the engine bay are like new after 9 years!

Otherwise with what would you clean these rubbers parst like hoses etc?? Any specific and safe product?

Thanks

 

[Quest]

Against most poster's wishers (*horror*), I don't spray/protect any rubber components underneath the engine hood so long as they are grease and oil-free.

I do,however, get really upset when certain rubber components underneath the hood swollen by mineral oil related grease or due to engine oil seepage/leak. I would have replaced them right away so as to restore proper functionality.

rubber components, elastomeric suspension parts, etc. under the hood or under the chassis will go bad eventually due to aging (rubber does age and go bad as time goes by), UV and ground level ozone. While one may be able to avoid UV deterioiation by keeping the car inside a closed car port, you cannot get away with ground level ozone, heat cycles, and age.

I simply replace the rubber components when I see them going bad. So far, radiator hoses last me some 180+kms before it calls for replacement, fan/alternator belts typically 120+kms before they get replaced due to squeaky noise (not due to age), and so on. Vacuum hoses, I replace them with sumitomos and mitsuboshis.

p.s. I haven't found any silicone rubber dressings that I like.

 

[moving2]

Most cooling system hoses fail from the inside out. Therefore, assuming a 9 year old, shiny, new-looking hose is in good shape may be wishful thinking.

 

[Auto-Union]

I use tire foam on my engine. Spray it down and wipe the dirt off and spray it again.

 

[kilou]

quote:

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Originally posted by moving2:
Most cooling system hoses fail from the inside out. Therefore, assuming a 9 year old, shiny, new-looking hose is in good shape may be wishful thinking.

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In 9 years I've done engine coolant flush several times and each time I have the opportunity to look at the inside end of coolant hose.....and they are still in perfect shape. The silicone is absorbed by the rubber and avoid drying in the inside too (not perfectly but it still helps a lot). Also on the surface it should protect the rubber in the event of an oil spill. I may want to replace these for peace of mind the next time I flush the system though.

For example on suspension/steering parts that get dirty all the time I think it really helps. I did the CV joint boots, the steering gear rubber gaiters and I also spray silicon on arm links: this prevent the rubber from drying/cracking and also lubricate the parts. Of course I had to change the engine mounts but I did not spray them with silicon. Now the new mounts have been installed 50,000km ago and I sprayed them when I installed them. The rubber on the old ones (front and rear) were cracked so maybe the silicon on the new one will help to prevent this (but I know that engine mounts are a very weak point on my car and need replacement anyway).

Well I may want to stop spraying silicon in the engine bay to avoid potential problem with O2 sensors but after 9 years I know that the silicon spray I use is safe for rubber otherwise everything would have gone bad much earlier I guess. I will for sure consider renewing my coolant hoses anyway when I'm due for the next flush which should be next year.

 

[kilou]

quote:

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Originally posted by moving2:
kilou- next time you replace those hoses, cut them length-wise and open them up. This will show you cracking and weakening of the material much better than peering into the hoses. I seriously doubt the silicone spray makes any difference on the inside of the hose.

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OK I'll do that when I'll replace them.

Just checked my silicone spray can and it mention it is good for rubber......but will destroy polystylen (styropor). Is this plastic used on automotive parts???

 

[Quest]

While most of the plastics used underneath the hood are of ABS/Polyethylene variety, occasionally, you still find Polystyrene or even traditional (*yuck*) PVC underneath the hood.

Occasionally, I see polystyrene underneath the hood being used as some kind of fan shroud that may have been related to A/C.

If your silicone spray mentioned about the ability to destroy polystyrene (packaging foam), most likely it comes with a carrier agent of strong solvency that is not good for rubber afterall.

In that case I wouldn't consider the benefits of the spray (damaging to plastics, yet safe on rubber? Oh, come-on now!)

 

[mburnickas]

I would use 50/50 mixture on the spray with water. Go over to autio and look around. there are thousands of people they spray XXX on hoses.

Also I would worry about vapor going into engine and hurting 02. The buring process should burn it off.

 

[moving2]

kilou- next time you replace those hoses, cut them length-wise and open them up. This will show you cracking and weakening of the material much better than peering into the hoses. I seriously doubt the silicone spray makes any difference on the inside of the hose.