Sweating Brake Fluid Hose

[MarekH]

Dear David,

With the prospect of mostly only poor rubber parts available these days, perhaps the thing to do is drop them all into separate jam jars of brake fluid and leave them for a month before looking to fitting them to the car.

It'd be a good candidate for a long term test and writeup.

kind regards
Marek

[Heuer]

Marek

My theory is the degradation has to do with regular movement through the hose - not sure if this is due to some abrasive effect but on my OTS the problem appeared after regular use and on the FHC started under my ownership where the car ceased to be a trailer queen and found the open road. SNGB have had a length of the same hose as mine steeped in brake fluid for three years without problem. The only difference seems to be fluid moving back and forth through the hose. I am open to other theories though. Also how do you measure the sweating of the hose if it is totally immersed in brake fluid?

[MarekH]

Dear David,

1/ re the jam jars:- I was thinking about the seals - if they are "bad", I'd expect to see a greyish haze around them after a while;
2/ I guess one could hook up a s3 windscreen washer pumps (?5 item) to a 12v battery and let the fluid circulate round for ever to check the movement theory.

Bear in mind that both the low and high pressure hoses have almost no fluid movement through them - the volume of liquid moving is only the gap between a piston and piston wall x 4 x about 1mm piston movement. There is plenty of friction and heat at the caliper end though.

kind regards
Marek

[vee12eman]

Hi,
Any possibility that certain types of brake fluid are more susceptible to sweating through than others? I know it's supposed to be the same stuff, whatever source you buy, but it clearly isn't as witnessed by the several different colours it comes in. Also temperature must play a part, the warmer it is the thinner the fluid will be. This also may explain why a trailer queen turned frequent use car is suddenly having problems as the under bonnet temperatures will be high (during usage) more often than if not used.

I have hose from SNG, live in warm temperatures with a V12 (very hot under bonnet temperatures so the fluid will be as warm/thin as it is likely to get), use the car fairly frequently (although not as much as I would like) but my hose shows no sign of sweating after nearly 4 years. I am not absoloutely sure which fluid I use, but I think it is Nulon DOT 4 (a local brand).

Regards,

[Heuer]

It does seem to be a lottery which is why I am championing the idea to only buy hose that is clearly marked with the manufacturers name, code and material. As far as I can recall my OTS (which twice suffered from sweating hoses) used DOT4 but no idea what was in the FHC. It seems Cohline offer two products which are immune from sweating and given the cost is minimal (compared to having to repaint your frames!) at 70p/100mm - 500mm required for a 3.8 - experimentation on different brands is probably pointless. Thing is Simon, both your hoses and mine were sourced from SNG and look identical but who is to know if the wholesaler ran out of the 'approved' stuff and supplied an alternative identical looking product to meet demand?

Simply buy Cohline 2337 or 2322 and make sure it is marked as such!

[gmunro]

Hi guys - fascinating subject and I really appreciate all the input to date. The final question after all the debate is ...... which Cohline product to go for ..... the 2337 or the 2322?

Brilliant research and thanks so much.

Kindest regards,

George

[Heuer]

Either will be OK. Suggest you order from Hutson as they have the correct type. Speak to Andy Raynes and mention the Forum.

[gmunro]

Many thanks David, I'll contact Andy as you suggest.

[Ropariva]

Hi
I just experienced this issue myself with supposedly correct reproduction "yellow stripe" hoses from a reputable supplier. This was after only 4 months and with virtually no use at all as the car is still under restoration.

My paint has suffered some discolouration as a result.
The brake fluid was Nulon DOT4.
A club member friend has reccomended I use silicon fluid once I replace my hoses, but that question is probably dealt with already in another forum topic.
Interestingly, it appears the car was still fitted with its original fluid hoses prior to the strip down, and they weren't showing any signs of sweating.

[42south]

Hi Guys

I've also had this problem down here in NZ. Finally after some searching I came upon this site in the USA: http://tiny.cc/bsmpxx He sells DOT approved 5/16th EPDM hose that is made by BF Goodrich in the states. The material is called 64A Santoprene. I checked on the Shurflo compatibility chart on the web and Santoprene and EPDM both have the same A grade rating for brake fluid. He states that he has never had a comeback in 7 years. Might be useful for our American mates

http://tiny.cc/bsmpxx

[Ropariva]

Well, kudos to XKs in the U.S. They have taken my direct feedback and the comments in this thread on board and have taken up the challenge of producing their own hoses. I will post any updates as they come my way.

In the meantime I will dig out my ratty looking Girling hoses that have remained sweat free for nearly half a century.

[PhilBell]

Can anyone tell me the internal diameter of the reservoir-master cylinder hose that I need please?
I need to order some Cohline 2337 today but forgot to measure the pipes last night.

[Ian Cooke]

Hi All

Could someone please give me a step by step guide to replacing the brake and clutch low pressure hoses on my S2 FHC as they are sweating profusely! I have taken David's advice and ordered Cohline hose.

Not sure if I will need to bleed the brakes as part of the process.

Thanks

Ian

[mgcjag]

Hi Ian...you will need to bleed the systems...assuming that you brake fluid could also possibly do with replacing.....drain fluid from brakes and clutch..open nipples( one at a time) and pump out the fluid ( or if you have a vacume suck it out)..close nipples...remove sweating hoses and replace with new......refill with fresh fluid and bleed both systems till nice clean fluid comes through each nipple....job done....also worth checking clutch adjustment whilst your there.... Steve

[Ian Cooke]

Thanks Steve

I wasn't sure whether I would need to bleed the brakes as David / Angus had suggested in an earlier post that this wasn't necessary:

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.

[christopher storey]

I think Steve is perhaps being pessimistic : provided you do not operate any part of the system while you are changing the hoses, you should not introduce air to the high pressure part of the system. So , siphon the old fluid out of the reservoirs and the down pipes one at a time, change the down hose and refill with fluid one at a time, and then allow sufficient time for gravity to do its job in displacing the air in the hoses - leaving for perhaps 1 hour should be enough . At this point you can try operating the pedal, and providing that it pumps up hard you should be ok. If, however, it goes squidgy ( there's a word for you ) then you will have to follow Steve's procedure

[mgcjag]

It really is one of those questions that if i had said no you dont need to bleed then someone would have posted yes you may introduce air.......Haveing to ask for step by step instructions to replace the hoses im asuming that Ian probably dosent know what fluid is in the system....so to avoid mixing a full replacement would be advisable....Steve

[Ian Cooke]

Many thanks Steve and Chris. Its certainly very helpful and reassuring for an inexperienced owner like me to have confirmation that I'm not missing something obvious.

I'll go for the more straightforward method and hopefully manage to avoid introducing any air into the system.

Ian

[JJC]

SNG or XK's Unlimited will send you all the correct brake hose you need overnight.

Any E, any Jaguar. Hope this helps.

JC

[Heuer]

SNG or XK's Unlimited will send you all the correct brake hose you need overnight.

Unfortunately not. If you read this thread from the start you will see I bought hose from the usuals and it sweated. 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. The only one that will not sweat in my experience and tests is the Butyl rubber aka IIR Cohline 2322-0613 with blue cloth braid moulded cover and blue inner however it does not have a yellow stripe and has a cotton weave cover so not for the concours-ista's. If you insist on using any other hose then it needs to be replace every two years along with the brake fluid.