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Vladimir Ivanovich Kirillov
Prolific User
Username: soviet

Post Number: 122
Registered: 2-2013
Posted on Thursday, 05 March, 2015 - 09:51:   Edit PostDelete PostView Post/Check IP

I can just see it now. I am with my new Soviet wife with my 1976 Cadillac Fleetwood parked outside a fancy restaurant in one of our coastal cities and having had a good meal we get into this pristine monster of a car I start the car and it bursts into flames perhaps because some fool had flicked his lit cigarette butt under my car. A bad ending to a good night. No this didn't happen but indeed it could have. This car has not done even 76,000 miles. It looks brand new. The only problem I ever had with it was a fuel starvation problem and having gone crazy contacting seasoned Cadillac experts in the USA (who did not have the answer) I was beside myself trying to locate the bug. I had run fuel pressure tests on it and read the workshop manual. The manual proved to be useless. Eventually I decided to pull every thing apart from the fuel tank to the injectors. I found the problem was a piece of rubber hose that sits in the fuel tank and goes from the in tank pump to the steel outlet pipe had disintergrated. The work shop manual shows a picture of the pump but that picture does not show the little piece of rubber hose that was to cause me so much grief over time. Now I try to start all my cars when ever I can. So I get into the car the other day and I start it. Fortuneately for me, the mad scot who dwells with me had put a 20 litre container into our fuel reserve area that contained a mixture of kerosene and aviation gas and I had put this into the fuel tank. The car which always fires up first go started and ran like a hairy goat with a head full of acid. So I switched it off got out of the car and to my horror noticed a puddle of fuel under the car about 15 feet long. I put my head under the car and noticed it was coming from the chassis rail fuel pump. (Yes unfortunately its a fuel injected 8.2 litre monster) So then I hit the internet trying to find a new pump without much success. This morning I decided to remove this villainous pump and examine it more closely only to discover it was not the pump at all. No it was the 2 inch long piece of rubber fuel hose that goes from the steel pipe coming from the fuel tank to the chassis rail pump. Now I remember when I located the in tank pump rubber fuel hose problem that I made a point to check all fuel hoses from the tank to the fuel filter and to replace any that looked like they might cause a problem in the next five years and this is where I made a big mistake. The squeeze test to check rubber hoses from the outside is a waste of time. It seems to me that petrol rots the hose from the inside out although I have replaced many fuel hoses on other cars in the trade that had visible cracks on the outside. Therefore gentlemen I have arrived at the conclusion that the only way to check a rubber fuel hose is to pull the mongrel off, look at its end and then squeeze to see if any cracks appear looking at the hose end. Now I have become completely paranoid and have decided to keep a diary of all my cars and replace all fuel hose after a period of 5 years, in fact I might even put it on the keel of the brake fluid changes that I do every 2 years and change all fuel hoses every two years. It is absolutely ghastly to think one of my pets could have burnt itself to the ground over something as cheap as a rubber fuel hose. Along with batteries and politicians I now don't trust them. Mind you if I did a check over on a customers vehicle and pulled all the fuel hoses off and gave them my crazy Russian end of hose crack test, any boss would spit his teeth out. But I thought I would relay this saga to you fine folk if only in repayment for all the information and advice I have got for free from this forum. Oh sure I always keep a loaded fire extinquisher in my car. But of course that would not have saved me from the Soviet wife scolding I would have got as they just don't understand old cars and simply deal with these types of situations viciously.
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 1233
Registered: 6-2009
Posted on Thursday, 05 March, 2015 - 10:54:   Edit PostDelete PostView Post/Check IP

The problem here, my dear Vladimir, is presuming that either an individual incident/data point applies more broadly, or that well-controlled test data necessarily means anything that's applicable to an individual case.

It sounds like you have extensive experience and should know when paranoia is useful, versus overreaction. Also when "bending the rules" is likely to be OK as opposed to an absolute no no.

Always keep those things in mind.

Brian, who knows nothing of wives - Soviet or otherwise
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Lluís Gimeno-Fabra
Grand Master
Username: lluís

Post Number: 345
Registered: 8-2007
Posted on Thursday, 05 March, 2015 - 18:33:   Edit PostDelete PostView Post/Check IP


Rubber fuel hoses are no more complicated that any other elastic element. Elastomer-based they have structural and chemical properties.

I learnt that structurally a fuel injected car uses multilayered hoses. because otherwise a single ply will not withstand pulsation and mechanical clamping.

I also learnt that ethanol slowly rots fuel hoses and o-rings... in a 20 year old engine.

So you do not need paranoia: simply use the correct hose SAE 30 R9.

Never base a fuel hose choice in max temperature and max burst pressure specification only. These are over simlplified, you will need cyclic pulsation resistance, and layer structure at least to be complete.

In case you use 10% ethanol fuel or even 5%, make sure o-rings and hoses are throughly inspected every year. An excellent test is to see whether they smell of petrol from the outside, as they get porous.

In order to replace the elastic lines (of excellent quality when OEM) in many of our V8, the full plenum system must be taken appart and I would not like doing this every 2 years (15000 miles in my case).

As for the low pressure return and ventilation hoses, I do not see the need of getting paranoid with those.

The high pressure (5bar) inlet to the rails and regulator may be more of an issue, in particular in the hot valley of the Vee.

Best regards,

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Bob UK
Unregistered guest
Posted From:
Posted on Friday, 06 March, 2015 - 08:18:   Edit PostDelete PostView Post/Check IP

I am one step below paranoid about fuel leaks, call it being aware.

I advocate SS braided with Teflon liner.

Modern fuels attacking bits of a fuel system is well known but no manufacturer gives advice on what to do with older cars.

Fortunately for us Brits our fuel seem reasonably benign.

The very worse stuff to use is that general purpose plastic pipe with or without the string reinforcing. Guaranteed to leak soon. I have never actually found a use for the stuff. Because it goes hard.

car fires are rare, fortunately people seem to be lucky. I have seem leaks that should be on fire but for luck.

Beaware of fuel in the vee of vee engines. Those overflow pipes are important seen lots of cars with missing or wrong pipe fitted.

The first reported car fatality was in 1890s by a guy checking fuel level with a lighted match. The local coroner said he felt that death by car was going to be common.

Saving grace of car petrol fires is that seldom do they immediately explode into a fireball. It gives time for owner to stand and watch hoping in vain the the fire brigade will save the car. Usually they turn up when the fires well alight and fill the car with water then chop the battery cables.

There are kits on the web that are diy non swaged SS braided. Not recommend for brakes (illegal in the UK on brakes) but good on low pressure say 300 psi. Cut hose with angle grinder. Fit ferrules and tighten special union. Very neat especially if heat shrink is fitted over the joint or whole pipe.
Brass is best for connecting to the SS union on the braided hose and combination of colours looks properly engineered. SS on SS threads can pick up, galling

All easy stuff
My local thread and pipe guys have a fitting for every application. 45 degree elbows for instance. All reasonably price also he does helicoiling.

Also he makes specials in his small machine shop.

Fortunately I have a good lathe and I collect lumps of brass. So any fuel leak problems are easy to sort.

I use kunifer for fuel lines with soldered on brass unions. The hot rod guys use stainless pipe with brass unions. For hoses on carbs l like the modern version of Smith's petroflex, with wide hose clips that come with the hose. It's SS braided "rubber" that clamps.
Also sometimes I use a airline crimping tool and permanently crimp the brass fittings in the pipe. This method suits old cars and looks period.
For some reason I will never understand is people using Ill fitting or adjustable or mole grips on unions. Nothing worse than chewed up corners on unions.
I like the way my petrol system is laid out, the simple union to disconnect both carbs. Very good quality. Lasts forever. Not used on my car, lpg, but does look nice. Cadmium plated brass light rub with green scotchbrite.

Tip. Copper washers if heat to dull cherry red and quenched in Water will soften and be reusable. However New ones arnt expensive. Copper age hardens as well as work harden so new washers heat to etc etc, for a perfect seal. Also solid copper head gaskets. Brit motorbikes

All easy just time consuming. Not expensive to do.

(Message approved by david_gore)
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 1235
Registered: 6-2009
Posted on Friday, 06 March, 2015 - 09:44:   Edit PostDelete PostView Post/Check IP

When it comes right down to it the distillation of Lluís' comments is: Use the right part for the right purpose.

Flexible fuel line that gravity feeds fuel to a pump does not need to be the same as the flex lines that feed constantly pressurized fuel in an injection system. That's why there are different SAE specs for each of those hose purposes. It is critical to know this sort of information and to do one's homework if it's one's "first time at the dance" for any repair. This cannot be emphasized too strongly nor too frequently.

An ounce of prevention . . .

As far as the endless blaming of "Satan Ethanol" for every issue with "rubber" parts in fuel systems, I want someone to find me a catalog for fuel lines, seals, etc., that's less than 35-40 years old that doesn't specifically note that the elastomers used are compatible with ethanol. It's been in the fuel in the US, and elsewhere, since I first started driving in the 1970s and has never been absent in the following decades. Manufacturers had taken this into account a long, long time ago. Old "rubber" does eventually perish, no matter what its application.

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Bob UK
Unregistered guest
Posted From:
Posted on Saturday, 07 March, 2015 - 07:02:   Edit PostDelete PostView Post/Check IP

use the right part for the right application.
too many rights, grammar.

Use right part for the application is my favorite rant.
URPA. Yerpa.
when problems occur having a layer of wrong parts in the problem just adds to the work.

YERPA. I have made a new word up.

Plastics degraded as well. Teflon is quite stable. I have seen plastic fuel lines snap in cold weather.

Metal pipes also don't melt.

A lot of old cars didn't use hoses, instead a coil or loop in the metal pipe. Pigtail. This works well and lasts well and easy to remake.

Citroen 2CV doesn't have any brake flexibles just coils.

I did think about fitting coils to the six hoses on my car that don't move with the suspension, but the extra joints mean more leak potential and hoses aren't that expensive and a direct fit rather than modifying pipe work.

These hoses could be pigtails.
2 rat trap to front subframe.
2 hoses from ride valves to rams
1 hose hp to ride System.
1 hose hp but running on low pressure return from ride system

Sometimes the pipe layout designers go the scenic route to allow for relative movement.

Always use original clipping points and be wary of fitting extra clips especially near subframes.

My lpg feed line is not clipped for the first 14" and has a 90 bend before the first clip. This works like a pigtail.

Note the ride system return is a low pressure return but sometimes the ride valves can fire a slug dot back to the dot tank. So this hose must be hp and not lp with hose clips.

(Message approved by david_gore)