Disco 2 oil mist on silicon hoses

Hi All
Yesterday I found slight oil mist on the surface of silicone hoses just after turbo and before intake manifold (before the intercooler was dry).
Has any experienced the same? Is it due to the quality of hoses (porous)?

berg450 said:

Is it due to the quality of hoses (porous)?

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I'd say yes as silicone is porous to oil and fuel unless the inside wall is treated to prevent direct contact with the silicone rubber.

That explains a lot - ta.

In that case maybe the original used black hoses are even better (I could not see them delaminated but found oil on them as well)

Same on my 200 and my d3.

berg450 said:

In that case maybe the original used black hoses are even better (I could not see them delaminated but found oil on them as well)

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With age, pressure and temperature, the tensile strength of most hose materials start to weaken. Strictly speaking, silicone has excellent oil and fuel resistance properties, in the sense that it does not decompose when in contact with these fluids, even at high temps. The problem is to do with the permeability of the silicone rubber that allows vapour to escape, even when used for coolant hoses.

NPG said:

With age, pressure and temperature, the tensile strength of most hose materials start to weaken. Strictly speaking, silicone has excellent oil and fuel resistance properties, in the sense that it does not decompose when in contact with these fluids, even at high temps. The problem is to do with the permeability of the silicone rubber that allows vapour to escape, even when used for coolant hoses.

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my silicone hoses are new, used only for a few months. Probably as it is a cheap one, not so good quality, right?
Do you think it worth changing them to a better quality like Samco?

Do

berg450 said:

In that case maybe the original used black hoses are even better (I could not see them delaminated but found oil on them as well)

Click to expand...

you mean you found the Same kind of oil mist on the original black rubber hoses?if so it may be that something is slightly leaking oil under pressure

berg450 said:

my silicone hoses are new, used only for a few months. Probably as it is a cheap one, not so good quality, right?
Do you think it worth changing them to a better quality like Samco?

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I have never used silicone hoses, o'rings, bushes, etc. in applications where they can come into contact with oil and fuel compounds. Nitrile rubber (NBR) and Flouroelastomer (FLE) are the materials that perform best under such conditions. Note that, depending on the blend, other terms may be used to describe FLE such as FKM, FMVQ, the brand name Viton or simply Flouro. All of them refer to the same group of synthetic rubber based on fluorocarbons. So, for your type of application, you need to look for silicone hoses that have a high concentration of FLE or any of its derivatives. Perhaps, another user on this forum who have used this type of hose can recommend a brand, based on experience.

Wrap some duct tape round the hose... if the tape has oil on its surface, its not the hose, its external.

I have the oil mist only on the hoses and no other places (even the steel pipe which connects to the silicon hose is bone dry)

flat said:

Do


you mean you found the Same kind of oil mist on the original black rubber hoses?if so it may be that something is slightly leaking oil under pressure

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Actually it was more like leak and not mist and probably came from the area where it connects to the steel pipe or turbo. And could be found on the bottom of the hoses. In case of the silicons it is different.