Sweating Brake Fluid Hose

andrewh · Post by **andrewh** » Wed Jun 12, 2013 6:15 pm

Perfect. Will do and report back. Thx

Post by **Heuer** » Sun Jun 16, 2013 6:01 pm

Just fiddling with newly restored car (< 12 months) done to a high standard and found the hoses are all sweating. They look like the Buna-N all the usuals supply! Scary!

andrewh · Post by **andrewh** » Sun Jun 16, 2013 6:03 pm

I just viewed a car restored in about 1984 and the hoses are perfect. Of course they may have been correct rubber

Post by **Heuer** » Sun Jun 16, 2013 6:05 pm

They would have been able to source the original Girling items back then. It would be interesting to do a survey. Please go out and check your hoses and report back. The 'sweating' will be evidenced by a slightly oily feel to the pipes (as though WD40 had been sprayed on them) and afterwards your finger tips will feel tacky.

Post by **Heuer** » Tue Oct 15, 2013 1:51 pm

This is what the sweating hoses look like:

I wiped most of it off until it occurred to me I should take a photo. Those are beads of brake fluid which appear on the surface having migrated through the hose! The hoses are a year old.

Post by **Heuer** » Wed Oct 16, 2013 4:23 pm

Ordered the proper stuff from Hutson's - Cohline. Andy to the rescue again!

andrewh · Post by **andrewh** » Sun Oct 20, 2013 6:24 pm

Very interesting and valuable thread. I just sourced new old stock genuine Girling but only two items. So now face a conundrum namely whether to fit the two original items and find the other stuff for the third. I wonder whether it would be possible to get some cohline braided and finished with a sheaf at either end in steel which whilst non original would look very nice. I have had fuel pipe made like this before and looks much better than glossy rubber. Is Cohline shiny David?

Post by **Heuer** » Sun Oct 20, 2013 8:42 pm

Cohline sold by Stevson is cotton braided, Cohline sold by Hutson's is smooth. I only have experience of the Stevson hose which has remained sweat free on the OTS. I spoke to the ever helpful Andy Rayner about my FHC problem who told me their hose is made by Cohline but is smooth with no braid. Others (Angus) have said this is a good solution so I am happy to give it a try. Beggars belief SNGB and others still sell the sweaty stuff

Three days after cleaning the hoses on the FHC they are covered in brake fluid - and what comes out (fluid) must go in (moisture). Known problem, known solutrion but Hutson's and Stevson are the only people who seem to care.

Post by **1954Etype** » Sun Oct 20, 2013 10:22 pm

I've used the stuff Hutson supply for years - not cheap but doesn't sweat!

PeterCrespin · Post by **PeterCrespin** » Mon Oct 21, 2013 5:05 am

1954Etype wrote:I've used the stuff Hutson supply for years - not cheap but doesn't sweat!

I thought you used silicone fluid?

Post by **1954Etype** » Mon Oct 21, 2013 8:03 am

PeterCrespin wrote:
1954Etype wrote:I've used the stuff Hutson supply for years - not cheap but doesn't sweat!
I thought you used silicone fluid?

I do on my cars but have also used non silicone for customers.

Post by **Heuer** » Mon Oct 21, 2013 4:56 pm

I cleaned the hoses of sweating fluid 6 days ago and this is what they look like today:

Hose came from SNGB - avoid! I bought some Cohline 2337 hose from Hutson's which they say will not sweat. However it does not seem to be the same stuff as I used on my OTS. That came from Stevson's and had the blue braid and blue inner and was Cohline 2322:

Further research says Cohline 2337 EPDM was manufactured specifically for VAG so it is not in the general catalogue: "Low pressure hose for connecting fluid reservoirs to master cylinders. Resistant to all types of brake & clutch fluid. 7mm ID. Will easily push on 8mm hosetail. Supplied with IVA declaration."

You can also buy it from these suppliers at ?7/metre:
http://www.cbsonline.co.uk/product/Brak ... ose_BFHOSE
https://www.merlinmotorsport.co.uk/p/7m ... m-m-sph8-4

Patrick NICOLAS · Post by **Patrick NICOLAS** » Wed Oct 23, 2013 11:46 am

David, thank you for this very comprehensive work.

Since this subject is brought to the surface, I looked on my 1965 s1. The three hoses are healthy. I think I'm lucky because they are certainly not original. One is smooth, the other is dressed in linen, the third is plastic made. But no sweat.
So, I'll leave them alone for the moment.

wol916 · Post by **wol916** » Wed Oct 23, 2013 10:51 pm

I used www.advancedfluidsolutions.co.uk for the fuel pipe I chose to use fuel injection pipe inside the boot to stop the sweating problem as more and more ethanol is added to fuel these days.
They stock SAE J30 R9 fuel hose and the range of CHOLINE hoses for dot 3&4 brake fluid.
Fuel hose ?3.99 per meter
Brake hose ?6.89 per meter
Deliver to UK starts at ?1:15

Warren

jag68 · Post by **jag68** » Fri Oct 25, 2013 1:07 am

I haven't read all pages of this thread so this might be reptitious. XK's Unlimited in now selling yellow stripe hose - Part No CO-18717

Post by **Heuer** » Sat Oct 26, 2013 10:00 am

Just swapped over the sweating hoses for the new Cohline hose (on the 3.8 you only need half a metre) and it looks as though the old hoses have started to disintegrate from the inside given the colour of the brake fluid I extracted - it was grey/black. I have been corresponding with Julian Barratt over this and he assures me they have had a test hose filled with brake fluid for the last three years without problem so they are somewhat puzzled. He is however investigating the supply of Cohline and in the meantime I am sending my old hoses back to them for Peter Stant, the SNGB technical guru and QA manager, to investigate further.

Angus assured me I could simply empty the bottles, remove the hoses, refill and wait for the air bubbles to plop out - no need to bleed the system - and sure enough they did. However as I wanted to change the hydrostatic clutch slave to a conventional one I bled that circuit and found the black fluid.

I then bled the brakes but interestingly, whilst some grey fluid came out, it was nowhere near as bad as the clutch fluid for some reason. If you look at the above picture you can see the two brake fluid bottles are darker than the clutch bottle so it seems dirty fluid gets mixed there but not in the clutch bottle because it stays in the cylinders. I wonder if it is regular movement of the fluid in the hose that exacerbates the problem and why a static test does not shoe up a problem?

For the time being, and until Julian can give us a definitive answer (bad batch, wrong type of hose etc), I suggest you simply visually check your hoses once a week to see if you are effected. Keep a particularly watchful eye on the one closest to the frame.

As for the XK's 'yellow stripe' hose you need to ask for details of what rubber it is made from. Quote "Low Pressure Brake Flex Hose With Yellow Stripe. Sold Per Foot. (Note: This is an attempt to replicate the original hose but it is of much larger cross section. It is a step in the right direction but IS NOT absolutely original.)" Looks like the yellow stripe has been painted on to me.

Best way to check is to ask for a SVA letter of compliance - this is what kit car builders have to include with all their documentation when submitting their construction for its first test - and proves the hose has been tested as safe for brake fluid. The kit car constructors/suppliers have been immensely helpful in my research on this subject and it was they who pointed me in the direction of Cohline as being the only acceptable SVA compliant vendor of low pressure brake hose.

Last yellow stripe hose I had fitted (admittedly 1999) sweated after 5 years. So this is the third batch of hoses I have had with this problem - maybe it is just me

jag68 · Post by **jag68** » Sat Oct 26, 2013 6:26 pm

You can also try this hose from AP Racing. I've used their hose over the years without issue. http://www.apracing.com/product_details ... p6614.aspx

Post by **Heuer** » Sat Oct 26, 2013 6:44 pm

Thanks but I will now only buy filler hose that has a SVA brake fluid compliance certificate or at least hose that is marked with the manufacturers name, part number and the type of rubber used as in "Cohline 2337 EPDM". The AP Racing hose has none of these.

MarekH · Post by **MarekH** » Sat Oct 26, 2013 7:04 pm

Dear David,

There are four potential sources of why the brake fluid may be discoloured black:-
1/ the sweating hose you are replacing;
2/ the master cylinder seal;
3/ the flexi hose between the two metal pipes; and
4/ the slave seal.

Whilst Angus's approach will work, it'd be interesting to see whether bleeding the brakes conventionally would yield a bit of grey fluid, clearer fluid, more grey fluid and finally black fluid, before the new brake fluid comes through. It'd also flush out any particles trapped in the line. What is more, if there is a chance of packing some red grease into the slave or master before reassembling any disturbed or replaced seals, then all the better.

kind regards
Marek

Post by **Heuer** » Sat Oct 26, 2013 7:25 pm

Marek

Bled the clutch conventionally today and even more black fluid came out. Also bled the brakes the same way and we had some grey fluid in the jar. I am going to replace the clutch high pressure hose as a precaution (it has a white stripe) and see what comes out. The master cylinder appears to be new, or at least overhauled, so I suspect the hoses. I have lots of red grease but as I did not rebuild the units on the FHC I don't know if it was used. Just had the original Dunlop callipers rebuilt (courtesy of Angus's brother in law - great service, contact Angus for details) with s/s liners and I used red grease liberally when putting them together.

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