Sweating Brake Fluid Hose

[Heuer]

Just noticed one of the hoses from the fluid reservoir has started 'sweating' and caused the paint to bubble on the frame. I had this happen about five years ago with the Girling 'yellow stripe' hoses but SNG insisted their all black woven hose was brake fluid resistant. Clearly this is not the case although so far it is only happening on one of the three lengths. This time I will try Halfords!

[Heuer]

Well that was a waste of time - brake hose "no longer stocked". A quick Google search suggests quite a few people have experienced the sweating pipe problem so anyone have a suggestion of where to find a supply of the good stuff? This is what Merlin Motorsport recommend:



Black fabric covered Nitrile butadiene rubber hose 8mm (5/16 inch) bore made by Sytec. Resistant to brake fluid. Used to connect brake resevoirs to master cylinders. Written specification available for SVA compliancy. ?7.20/metre.

[christopher storey]

David : I too have had this most annoying and damaging problem on my new rebuild . I seem to have solved it by using a Hutson special which is quite expensive (IIRC about 20 quidsworth ) and which is cloth covered which unless it is dyed black comes in a rather lurid mauve colour , but so far in about 18 months there has been no sign of penetration. Andy there is the manager , 01274 669052 ( forgive me if you already know this)

[Heuer]

Thanks Christopher, I will give Andy call. It seems a common and accepted problem with several people (not E-Type owners) saying they just wipe the pipe every so often. The lifetime seems to be 5 years max!

[1954Etype]

Agree with Chris, I use only this hose with no problems.

[paddy2181]

Hi. Try www.cbsonline.co.uk for brake hose. Supposed to be leak proof.
Was ?7 a metre last time I bought some.

[daverawle]

What do modern cars use? I would source some hose from a modern car dealerahip rather than chance the usual repro stuff. Or change to silicone fluid.
Dave

[Heuer]

Dave

Most modern cars have bespoke moulded tubes to perform the function of remote fluid bottles so I don't think that is an option unless someone knows of a part that will fit. Silicone fluid also seems to sweat from the pipes from reports I have read although without the same effect on the frame paintwork.

Update:

1. Spoke to Hutson's (Andy is on holiday) but they are out of stock. Said the pipe they use is braided and made in Germany. Unfortunately the braid is bright blue so the UK supplier dyes it black which stains when you handle it.

2. Spoke to Rob Beere and he says they use the braided stuff if they need it from Merlin Motorsport or Goodridge.

3. Spoke to Tim Griffin at CMC. They use the SNG supplied stuff with a shiny black plastic sheath the same as mine and they recommend changing the hoses every time they do a fluid change (2 years) as the 'sweating' is a known problem. Tim wondered why they could not use the high pressure hose as that seems immune to sweating, which is a valid point, but the inner diameter is too small. Tim did make say they do not like braided hoses of any type as you can't see what is going on behing the braid.

4. Spoke to Merlin Motosport. They supply FSE hose at ?7.20/meter or 72p per 4" and thought a 5 year life span before sweating started was "very reasonable". I ordered a length to give it a go.

5. Spoke to Stevson (who supply Hutson). Their hose (stained black or bright blue) comes from Germany and says it is "hugely expensive" but at ?18/metre they clearly are out of touch with the cost of E-Type maintenance! Offer no guarantee as to longevity. Out of stock at the moment.

6. Spoke to AP Racing Technical Services. They say their new 'Fluid Reservoir Connecting Hose' "no longer sweats". Available from Demon Tweeks at ?3.18 per foot it has a smooth black surface. "This hose from A P Racing is designed specifically for use with brake fluid and so it will not deteriorate as rubber hose would. It has an internal diameter of 5/16 Inch (8mm) so it is suitable for use with A P Racing fluid reservoirs with push on outlets."

Now - anyone know why we can't use bits of high pressure brake hose?

NB - one thing I have learnt is the correct name for this stuff is 'brake and clutch fluid hose'. Call it anything else and there is no end of confusion.

[PeterCrespin]

I went to Stevson's place and read the tehcnical letters from Dunlop. His stuff has a semi-gloss braided lump appearance but does not have a cloth exterior and it is lined IIRC. It is expensive but it has not leaked. He was adamant that he was the only one with the rights to the true leakless stuff but then he would say that. He knows his tubing though.

The part I found highly improbable (if not pure BS) in the FSE listing of hose types you included was the statement that the hose was suitable for both fuel and oil AND brake fluid. This is a chemical impossibility AFAIK. The specified rubber nitrile hose is correct for fuel and oil (non-polar solvents) but not coolant or brake fluid (polar solvents). It can't be both as they state - and as you are finding. Just because something doesn't dissolve into black go in the first hour doesn't mean it's properly specc'ed for that solvent.

It's the difference between polar and non-polar solvents and you can't have a normal rubber that suits both equally well - though nylons or polypropylene etc would be OK and I'm sure there is some blend somewhere that is the holy grail. I don't recall where EPDM rubber fits but roughly I think it's Butyl rubber for polar solvents and nitrile for non-polar. So coolant hose will resist brake fluid (both involve glycols) and petrol hose will resist oil too (both are hydrocarbons). Butyl for inner tubes, coolant and brake fluid, nitrile for petrol and oil. (AFAIK).

I think it's John Holmes on the E-type J-L list who is/was a rubber technologist and knows this stuff like the back of his hand.

Pete

[Heuer]

I went to Stevson's place and read the tehcnical letters from Dunlop. His stuff has a semi-gloss braided lump appearance but does not have a cloth exterior and it is lined IIRC. It is expensive but it has not leaked.
Pete

That sounds like the stuff SNG supply - a length on my desk at the moment. I have a call with the owner of Stevson's on Wednesday as he is out of the country at the moment so I will report back. However has anyone got any practical experience of long term use of any of this stuff?

Mine is:

Rubber/yellow stripe hose - 5 years
SNG semi-gloss braided - 5 years

Seems the consensus from suppliers and CMC is this is the typical life expectancy. Given that coolant hoses only last that long perhaps it is no surprise really.

[PeterCrespin]

Well I have several sets of old original hoses David that must have been in service 20-30 years before they were decommissioned. Apart from being a bit hardened they show no signs of ever having weeped or degraded in a 'soggy' direction.

This is really not new technology and they had the chemistry sorted 70+ years ago, so I'm struggling as to why it's still an issue today, apart from the fact that our vendors aren't chemists or rubber manufacturers. They presumably just go by what their primary sources tell/sell them. But then if a primary source can put BS into their hose specs like the FSE people did (who presumably based that on something else) I guess the vendors can be somewhat forgiven for selling stuff with a shorter than OEM functional lifespan.

Once it is brought to their attention as a real issue then you'd expect the pros to bang a few heads together and place their orders with serious suppliers. I mean look at the ubiquitous high-pressure flexi hose compound - you don't see those sweating or going soggy even after a couple of decades, of high-pressure fluid containment. They crack or fray, they don't weep....

The really unforgivable cases are examples like the well-known supplier in the South East who sells hose *clearly marked* as coolant hose (polar solvent) for petrol purposes (non polar solvent). It just swells and goes slimy after an hour in petrol, yet despite me pointing this out twice over a number of years they still sell exactly the same stuff. That is just scandalous.

Pete

[PeterCrespin]

Forget the FSE nitrile. It's fine for fuel but it can't hold brake fluid long term and shame on the for selling it IMHO. Nor did the original yellow stripe stuff look like that - it wasn't cloth exterior braided on my old samples but a smoothish thick wall hose. Neoprene would be very inert and good to use. Don't know about the Buna stuff, might be fine. Incidentally, that's not what the Stevson hose looks like if you were thinking they were the same from my description. It's similar but not the same stuff - the 'bumps' are much coarser in the rubber IIRC. I'll see if I can get a good picture tonight.

[Heuer]

Ordered a 1 metre length of pipe off Stevson ?18/metre + VAT & postage http://www.stevsonmotors.co.uk They say their pipe (which is blue on the inside and charcoal grey on the outside) is guaranteed impervious to DOT4 fluid but not DOT5 (silicone). I will do a comparison between all types of pipe and report back.

Whilst I was talking to them they mentioned they produce a IRS remote brake bleed kit including all pipes and brackets at £50 + VAT. Someone here was enquiring about a such a kit which is pretty much essential if you are re-building the IRS. I have added a link to the Knowledge Base.

Edit: I have now received the Stevson hose which is Cohline 2322 but with the outer fabric weave dyed grey. From all my research it seems only the Cohline hose will remain sweat proof as it has a Butyl IIR inner with a moulded in cloth outer. The cloth is there to protect because Butyl has a low resistance to oils and fuel but a very high resistance to glycol. Incidentally Butyl IIR is used in the manufacture of tyres and chewing gum!

So only one I can recommend would be the Cohline if you value the paint on your frames. Here is a summary of what I found out:

1. Demon-Tweeks supply this AP Racing 'remote reservoir hose' made from neoprene and AP claim it does not sweat:


2. The SNG hose seems to be made of Buna-N (tube and cover; aka Acrylonitrile-butadiene rubber) reinforced with an Aramid braid. Mine sweated after 5 years:


3. FSE supply their FH hose made by Sytec of Nitrile Butadiene rubber with a cotton yarn overbraid. Chemically similar to SNG one above:


4. Girling Yellow Stripe hose was OEM for the E-Type and apparently caused no problems. No longer available but the last 'new stock' I used sweated after 5 years:


5. VW Beetle/Bus owners and kit car builders seem to swear by this "brake refill hose" made by Cohline GmbH, specialist automotive hose manufacturers, made from Butyl rubber aka IIR (Cohline 2322-0613 with blue cloth braid moulded cover and blue inner). They will provide a certificate (for SVA purposes e.g kit cars) saying it is suitable only for DOT3 and DOT4 fluid. Supplier to Porsche, Mercedes, Audi and VW. Costs ?7/metre from http://www.carlton-hydraulics.co.uk


6. Stevson supply this hose - Cohline 2322-0613 dyed grey - at ?18/metre:


7. Hutsons and Merlin Motorsport supply Cohline 2337 EPDM at ?7/metre. It is actually produced specifically for VAG:


Note 1:

Nitrile (Buna-N, NBR)
Nitrile rubber is the general term for acrylonitrile butadiene terpolymer. The acrylonitrile content of nitrile sealing compounds varies considerably (18% to 50%) and influences the physical properties of the finished material. The higher the acrylonitrile content, the better the resistance to oil and fuel. At the same time, elasticity and resistance to compression set is adversely affected. In view of these opposing realities, a compromise is often drawn, and a medium acrylonitrile content selected. Nitrile has good mechanical properties when compared with other elastomers and high wear resistance. Nitrile is not resistant to weathering and ozone.
Heat resistance: Up to 212?F (100?C) with shorter life at 250?F (121?C).
Cold flexibility: Depending on individual compound, between ?30?F and ?70?F (?34?C and ?57?C).
Chemical resistance:
Aliphatic hydrocarbons (propane, butane, petroleum oil, mineral oil and grease, diesel fuel, fuel oils) vegetable and mineral oils and greases
HFA, HFB and HFC fluids
Dilute acids, alkali and salt solutions at low temperatures
Water (special compounds up to 212?F (100?C)).
*Not compatible with:
Fuels of high aromatic content (for flex fuels a special compound must be used)
Aromatic hydrocarbons (benzene)
Chlorinated hydrocarbons (trichlorethylene)
Polar solvents (ketone, acetone, acetic acid, ethyleneester)
Strong acids
Brake fluid with glycol base
Ozone, weather and atmospheric aging.

EPDM (Ethylene Propylene, EPM)
EPM is a copolymer of ethylene and propylene. Ethylenepropylene-diene rubber (EPDM) is produced using a third monomer and is particularly useful when sealing phosphate-ester hydraulic fluids and in brake systems that use fluids having a glycol base.
Heat resistance: Up to 300?F (149?C) (max. 400?F (204?C) in water and/or steam).
Cold flexibility: Down to approximately ?70?F (?57?C).
Chemical resistance:
Hot water and steam up to 300?F (149?C) with special compounds up to 400?F (204?C)
Glycol based brake fluids up to 300?F (149?C)
Many organic and inorganic acids
Cleaning agents, soda and potassium alkalis
Phosphate-ester based hydraulic fluids (HFD-R)
Silicone oil and grease
Many polar solvents (alcohols, ketones, esters)
Ozone, aging and weather resistant.
Not compatible with:
Mineral oil products (oils, greases and fuels).

Neoprene (Chloroprene, CR)
Neoprene was the first synthetic rubber developed commercially and exhibits generally good ozone, aging and chemical resistance. It has good mechanical properties over a wide temperature range.
Heat resistance: Up to approximately 250?F (121?C).
Cold flexibility: Down to approximately ?40?F (?40?C).
Chemical resistance:
Paraffin base mineral oil with low DPI, e.g. ASTM oil No. 1
Silicone oil and grease
Water and water solvents at low temperatures
Refrigerants
Ammonia
Carbon dioxide
Improved ozone, weathering and aging resistance compared with nitrile rubber.
*Limited compatibility:
Naphthalene based mineral oil (IRM 902 and IRM 903 oils)
Low molecular aliphatic hydrocarbons (propane, butane, fuel)
Glycol based brake fluids.
Not compatible with:
Aromatic hydrocarbons (benzene)
Chlorinated hydrocarbons (trichloroethylene)
Polar solvents (ketones, esters, ethers, acetones).

Butyl (IIR)
Butyl rubber is produced by many companies in different types and varies widely in isoprene content. Isoprene is necessary for proper vulcanization. Butyl has a very low permeability rate and good electrical properties.
Heat resistance: Up to approximately 250?F (121?C).
Cold flexibility: Down to approximately ?75?F (?59?C).
Chemical resistance:
Hot water and steam up to 250?F (121?C)
Brake fluids with glycol base
Many acids (see Fluid Compatibility Table)
Salt solutions
Polar solvents, e.g. alcohols, ketones and esters
Poly-glycol based hydraulic fluids (HFC fluids) and phosphate-ester bases (HFD-R fluids)
Silicone oil and grease
Ozone, aging and weather resistant.
Not compatible with:
Mineral oil and grease
Fuels
Chlorinated hydrocarbons.

More detail on the various materials here: http://www.sealanddesign.com/category/2 ... 62/62.aspx or download as pdf: http://dl.dropbox.com/u/8496016/www-sea ... gn-com.pdf

Note 2:

If a hose is able to 'sweat' brake fluid is it very likely to allow moisture to permeate the other way!

Note 3:
If you are building a C-Type or D-Type replica the SVA examination will require you to either have brake hoses marked as being suitable for use with DOT fluids or you will have to provide a letter of compliance from the hose manufacturer. Cohline will provide such documentation.

[Heuer]

Just to add, having installed them, 1 metre is enough for all three reservoir fluid pipes.

[on2wheels]

Good research David.

[Heuer]

Got to thank Angus and Christopher for pointing me in the right direction, Hutson's for honestly answering my questions and Pete for stirring my curiosity in the chemistry. Had to be done as I am fed up with repainting parts of my frame. As with many things on the E-Type we are at the mercy of suppliers who sell product that appears correct but don't invest in research to back it up. And it is not just individuals who suffer - Harry at E-Type UK and CMC have the same woes, only in bulk!

Did I mention "check your hose and frames"

[andrewh]

Further to this thread I am keen to buy the correct Girling yellow stripe hoses I know xk unlimited supply in the US but wondered whether anyone supplies here in the uk?

[Heuer]

The yellow stripe hose is no longer made by Girling and the ones you can get will sweat unless they are made to the same composition as Cohline. You car may look correct with the yellow stripe hose but your frames will not when the paint peels.

[andrewh]

Ouch. Any knowledge on the xk unlimited product?

[Heuer]

You need to find what the hose is made of and refer to the above information. If it is indeed made by Girling the information should be freely available on the web with a bit of searching. Email XK's and ask for more information. It must be Butyl (IIR) if you want to be safe.