Silicon hoses not for fuel or any other fluids?!?

[DyslexicSquirrel]

I just bought a couple of sets of silicon hoses off eBay and it says on the back that it is not to be used with fuel or any other kind of fluids. Is there a reason for this? The hoses look and feel far superior to the stock dry rubber ones... could it be because the fluids will break down the silicon after time? Could someone clarify this madness for me please...

 

[lagged]

madness? hardly. if it says on the hoses its not to be used for fuel/oil then it wasnt designed for such use. what you have are vacuum lines ONLY.

 

[tonysupra]

lagged ftw!

 

[KeithH]

silicone hoses will weep some fluids through the sides - most notably oil and fuel.

I've had success with using silicone hoses for rad overflow and windshield sprayers for the past nearly 10 years.

 

[souprat]

i got my silicon hoses from hosetechniques. they say theres are safe for coolant. i have coolant going through silicon hose to the TB and no problems yet. i would not use it for oil or fuel though. as for the e-bay ones if it says so then its true. it ok to be gullable sometimes.

 

[3p141592654]

from http://www.sourcerubber.com

Silicone The term “silicone” covers a large group of materials in which vinyl-methyl-silicone is often the central ingredient. Silicone elastomers as a group have relatively low tensile strength and poor tear and wear resistance. However, they have many useful properties as well. Silicones have good heat resistance, good cold flexibility and good ozone and weather resistance as well as good insulating and physiologically neutral properties.
Temperature range: –65° to 450° F (–54° to 232° C). Chemical resistance: engine and transmission oil (e.g. ASTM oil no. 1); animal and vegetable oil and grease; brake fluid (non-petroleum base); fire-resistant hydraulic fluid, HFD-R and HFD-S; high-molecular-weight chlorinated aromatic hydrocarbons (including flame-resistant insulators, and coolant for transformers); moderate water resistance; diluted salt solutions; ozone, aging and weather resistant. Not compatible with: superheated water steam over 250°F (121°C); acids and alkalis; low-molecular-weight chlorinated hydrocarbons (trichlorethylene); aromatic mineral oil; hydrocarbon-based fuels; aromatic hydrocarbons (benzene, toluene).

 

[Asterix]

Demonstration:
http://www.geocities.com/MotorCity/Garage/8255/hosetest.pdf

There are many kinds of silicone, fer sure, but this test shows me that the one typically used for vacuum hoses isn't compatible with engine oil.

Asterix

 

[3p141592654]

Good article Asterix. Its in agreement with my post above that silicone is not good when aromatics are involved such as fuel, engine oil, and so on.

 

[DyslexicSquirrel]

Demonstration:
http://www.geocities.com/MotorCity/Garage/8255/hosetest.pdf

There are many kinds of silicone, fer sure, but this test shows me that the one typically used for vacuum hoses isn't compatible with engine oil.

Asterix

Dude... that really helped alot. Hmmmm... All my hoses are for vaccuum lines right now... like it said. EXCEPT FOR ONE... for oil.... we'll see how it works out. WAIT! This is how bad things happen... I'm a gonna go take it off now...

 

[blackout_89t]

Go to a hydraulic shop and get the propper hose for the application you need.

 

[Asterix]

Good article Asterix. Its in agreement with my post above that silicone is not good when aromatics are involved such as fuel, engine oil, and so on.

Yup. I just thought the visual demonstration would be good for all to see. That's why I don't use any silicone hoses under my hood. It's an oily, greasy place there, and I'd rather not risk getting that silicone goo where it shouldn't be. Neoprene last for years. Sure, it's not brightly colored, but I'd rather things worked that looked pretty.

Asterix

 

[IJ.]

I use 2 silicone hoses for the turbo coolant in and out as the rubber just doesn't last there.

 

[3p141592654]

Viton might be better for those hoses.

http://www.mcmaster.com/param/asp/P...2727591933&ScreenWidth=1600&McMMainWidth=1271

 

[figgie]

Teflon FTW!!

 

[IJ.]

3P: The Silicone I'm using is the 500 degree one and seems to be holding up nicely, rubber was going crispy on the banjo fittings after shutdown.

What's the Viton rated to?
(without Permatex )

 

[3p141592654]

Viton is rated to 500degF as well. The issue with Silicone hose is that when exposed to aromatics it breaks down (Fuel, hot engine oil etc) and disintegrates into chunks. It works fine with coolant though, just keep the oil away. Teflon is also rated to 500degF and can be ordered with a nice protective covering. It is very stiff though, so not clear how you would get it on a barb type fitting. I have read Teflon fatigues under repeated bending, so may not be good in a vibrating engine application.

 

[IJ.]

3P: My 2 hoses are high in the Bay with not much chance of coming into contact with Oil and even less chance of Fuel (No gas in my car)!

I think/feel they'll be fine but if you're buying some 3/8 id Viton in bulk I'll purchase a few meters