Disintegrating fuel hoses !

[Richard Ibrahim]

Anybody else having this trouble ?

After running my Holley equipped GTD on the road for about 4years, I started to get some fuel leaks from the steel braided 5/16th hose supplied by Think Automotive in the UK. The leaks were adjacent to the fittings to the pumps/filters and on inspection I found that, under the braid, the rubber had seriously degraded to the point of disintegration. I put this down to a duff batch of hose and subsequently re-equipped the system with new hoses from the same supplier. This was about a year ago – so on firing up the car last week, I was more than a bit surprised (not to say pissed off!) to find a reoccurrence of the leaks with the same root cause. Over years I have seen several mid-engine cars burst into flames, so I am starting to understand why! Looking at pictures of other members’ cars, I can see that several are much the same as mine – so alarm bells have started ringing.
Today I discussed the problem with Think Automotive and they confirmed that this type of hose failure is becoming increasingly common. One obvious cause can be very high temperatures in the engine bay (no surprise there) but it seems that a secondary, more problematic, issue is the “ nasty aggressive stuff” being added to today’s’ gasolines. Think Automotive commented that they have been unable to get any info about these additives from any of the oil companies, and therefore said any answer to the problem was “ not going to be easy ”. Telflon linered hose could be an answer – but sizing and fittings would need to be changed, and as it is much less flexible, routing could be difficult. We came to conclusion that the only real safe solution was solid piping – either aluminium or copper.

My only advice is to make sure you regularly check your car, unless you want an exciting, but rather expensive barbecue!

Any comments ?

 

[Russ Noble]

This is a problem that raised it's ugly head in New Zealand several years ago with the change to unleaded fuel. In that case the problem was the fuel. The government and oil companies denied there was a problem but an investigation by aviation authorities after the crash of a home built plane laid the blame squarely on the fuel. Also a similar investigation into a tourism jet boating incident blamed the fuel and suggested they should use aviation fuel in this case to overcome the problem.Someone more qualified than I may be able to give more details but I believe the cause of the degradation is the high level of aromatics present in the fuel as lead replacement and this attacks some hoses and other rubber parts that in the past have been perfectly adequate for the job. Nitrile I believe is one of the inadequate materials. If you're interested check out the long term health ramifications of high levels of aromatics also!

 

[Mark Worthington]

I'm not sure what oxygenates are being added to gasoline in the UK, but I can tell you that's the cause of your problem. In the US the culprit is MTBE in gasoline, which after about a year causes the rubber in standard fuel hose to become porous. If you upgrade your hoses and fittings to super-expensive teflon then the problem will go away. Last time I researched this issue (about a year ago) I was surprised to find that Earl's or Aeroquip hadn't yet released an MTBE-compatible braided hose. Obviously, the OEM hoses are OK for oxygenated fuels.

 

[wpeter]

ATL and Fuel Safe have bulletins out regarding their products in reference to this problem. Their bladders are made for either alcohol or gasoline but not both. They are working on a suitable material ,but, at this time don't have a replacement. They recommend inspection yearly as well as emptying the bladder during extended storage. Check their websites for info. They are leaning toward a stiffer material with more resistance to breakdown. The problem is it is much stiffer than their older style material and makes it impossible to push into the small openning of older race cars.

 

[Trevor Booth]

Goodridge at one time had a convoluted PTFE lined hose (ser 210 ??) which was excellent for fuel lines with tighter bend radius than semi rigid PTFE. It was not all that expensive.

 

[Chris Duncan]

You can't run hard lines everywhere because you need a flexible connection to your motor to allow for mount movement. I've seen a combination of hard lines and flexible teflon hose.

Aluminum is superior to copper. It's cheaper than running all Teflon hose but you'll have more fittings because of the transition hard to flex and back.

You have to be more careful with hard lines, it's easier to wear a hole in them, and don't even run them near positive wiring like main alternator terminal, starter, or battery. A positive connection shorts on the metal and burns right through then high pressure fuel sprays right on the arc. Instant fire.

Nissan used to put their EFI fuel filters right by the starter positive. Twice in 3 years we had fires at the Nissan dealer. Admittedly while changing the filter but it's still an issue.

 

[Simon]

Richard,

I had exactly the same thing with my GTD.
As it had been built for fourteen years and sat unused in a garage for nine of them, I sort of expected there would be problems and replaced all the fuel hoses as a matter of course.
Better to be safe than sorry.

Simon

 

[Peter Delaney]

There was a thread on this subject a year or 2 ago & the conclusion seemed to be that nobody made braided hoses that could resist the MTBE additive (which I christened "Mean Time Between Explosions !) in the long haul. Everyone with these hoses reported vapour smells from an early stage.

I decided to test braided against the normal high quality rubber fuel hose, so did a bit of both - surprise - when I stick my nose on the hoses, I can smell on fuel braided stuff, but nothing on the boring old rubber hoses !

I am inclined to replaced the braided hoses with rubber, and look at some of the "dress-up kits" which allow you to sleeve it with an outer layer of braiding & add all the correct looking (fake) fittings - JEGS have quite a good range of this stuff.

Kind Regards,

Peter D.

 

[Richard Ibrahim]

Good point,Peter.I came to the same conclusion that a good quality reinforced rubber hose was a better bet and until I find something better, I have repiped my car the boring stuff!I would advise against overbraiding it though, as this prevents visual checking for deterioration.

 

[Craig White]

My GT40 is four years old, has sat around a lot. I haven't even checked the braided hose, but some of the rubber hose has gone hard and cracked. Car has quite a bad fuel smell. I just thought I would be tighening up a few connections and replacing the deteriated fuel lines.

Thanks for tips guys, will also be checking the stainless now. I assumed it would have been better quality, than plain rubber lines, looks like it might not be.

 

[Mark Worthington]

[ QUOTE ]
Thanks for tips guys, will also be checking the stainless now. I assumed it would have been better quality, than plain rubber lines, looks like it might not be.

[/ QUOTE ]

It's wonderful stuff for avgas and jet fuel, for which it was designed, and for race gas, but pump gas with MTBE is a problem. Like I said earlier, I'm surprised nobody has come up with a better solution, since so much of the stuff gets used on street cars.

 

[Paul Thompson 'Hooligan']

We have some 'double braided' hose on Roy's GTD - running from HP pump to fuel rail. It has a steel braid within the rubber (or whatever material it is) section and then another stainless overbraid too. Does anyone know if this stuff is any better?

We have not detected a fuel smell thus far but I'd hate to have a leak at 50-60psi. /ubbthreads/images/graemlins/blush.gif

 

[BenL]

MTBE is being banned in some areas, so it's being replaced with ethanol, which is also damaging to rubber and aluminum.

 

[Richard Ibrahim]

I think you are right to be even more worried about fuel-injected systems.This is a quote from the Think Automotive brochure:- " Until recently all hoses offerred for oil were suitable for pump fuel, however two things have happened that have altered the situation.Firstly,fuel injection has introduced the phenomenon of 'sour' fuel in the return lines where aeration introduces peroxides into the fuel, secondary the removal of lead from fuels has brought about the use of additives to improve the octane rating.Both of these moves produce a more aggressive mixture that can cause swelling and permeation(fuel smells)in all synthetic rubber hoses.Only TFE or hoses to specification SAE30J/R9 are completely suitable for fuel injection returns and more exotic fuels".
Under this spec. the only hose shown is an Epichlorohydrin(black rubber)covered textile reinforced hose. This has a very thin, but tough tube of flouro-elastomer"varnished" onto the the existing liner to protect against sour(oxidised) fuel.100psi working pressure and 150degC temp resistance.It works out at about £17 a meter - but it could be worth it !
If this problem is a widespread as it appears, just think of all the cars all over the world,now running on modern fuels and old crumbling hoses. Could be the right time to get into the fire extinguisher(or skin graft)business !