[v12-engine] FI Hose Ferrules...Functional or just pretty?

The question routinely comes up on J/L, and I get my share of
personal e-mails also, on whether these things actually serve a
purpose, or are they just there to make the engine look pretty, or
just to make the end of the hose looked finished.

I daresay, I have probably done more actual measurements on these
ferrules, the hose barb connection, and the FI hose itself, than
probably anyone…with perhaps the exception of the original
individual/team that did the original design.

Below a a quick summary of that information.

  1. They do add a bit of ‘‘color’’ or ‘‘dressiness’’ under the hood.
  2. They do make the hose ends look finished.
  3. More importantly…They Do Work.

The inside diameter of the proper FI hose to use is 7.9mm, 5/16’’.
The OD of the FI hose (non-fitted) is appx 14.5mm.

The OD diameter of the outer edge of the injector barb, or rail
barb is appx 10.0mm. The OD diameter of the lower end of the barb
connection is 7.9mm. (where to ferrule fits).

The ID diameter of the ferrule, where the OD of the hose seats is
14.5mm.

So the ID of the hose is 7.9mm. The outer edge (the OD) of the barb
is 10.0mm. The appx 2.1mm difference is what makes the seal of the
hose to the barb.

As the hose is shoved onto the barb, the OD of the hose expands
appx 1.5 mm. So the OD of the hose is now appx 16mm. The ID of the
hose has also expanded. You can’t visually see, or measure this,
but you know it had to, to fit over the outer edge of the barb.

Now the important part. When the ferrule is in place, and the FI
hose is fully seated into the ferrule…the ferrule has effectively
squeezed (compressed) the hose back down to its’
original…preinstalled diameters…both ID and OD, forcing the ID
of the hose end back onto the bottom end of straight portion of the
injector barb. In doing so, it has also squeezed the ID of the hose
tighter onto the outermost edge of the lower barb. And the final
seal is thus made.

Perhaps a bit hard to visualize with words. One of these days, I’ll
post my diagrams on the web site.

For now, I hope the above helps.

SD Faircloth
www.jaguarfuelinjectorservice.com–
www.jaguarfuelinjectorservice.com
Jacksonville, Florida, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

In reply to a message from SD Faircloth sent Thu 22 May 2008:

Great commentary David. I too believe the engineer who designed
this fuel rail system purposely placed those ferules to perform the
function you have measured and so clearly describe. The guy was
providing additional functional insurance to the ‘Barb’ system
which works so well provided one does not create leak passages by
cutting into the barb shoulders on the barbs. I have taken to
smoothing up these shoulders to insure any scoring of the barb
shoulder is removed. Removal of any shoulder material in reasonable
sharpening of the barb should be accomodated by the hose as it
settles on the barb shoulder. Has anyone attempted to repair a
damaged barb shoulder by soldering/brazing additional material back
onto the barb shoulder and then shaping to the original dimensions?
Kirby/Roger B./Richard D./George B./… your comments
please. Removal of old hose with the soldering iron blade seems to
be the least damageing to the Barb-shoulder. Best, JW

Any ‘Super Quail’ at the Ranch yet?–
The original message included these comments:

  1. More importantly…They Do Work.
    The inside diameter of the proper FI hose to use is 7.9mm, 5/16’’.
    The ID diameter of the ferrule, where the OD of the hose seats is
    So the ID of the hose is 7.9mm. The outer edge (the OD) of the barb
    hose is fully seated into the ferrule…the ferrule has effectively
    squeezed (compressed) the hose back down to its’
    original…preinstalled diameters…both ID and OD, forcing the ID
    tighter onto the outermost edge of the lower barb. And the final
    seal is thus made.


86XJ-S cpes, Ballet I, Act II, 288 Dana
Fresno, CA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

Kirby once said he gripped a damaged barb with a pair of pliers and
turned it, presumably shaving off some metal. I’ve never tried it.

Ed Sowell
1976 XJ-S
http://www.efsowell.us/ed/myJag.html

cutting into the barb shoulders on the barbs. I have taken to
smoothing up these shoulders to insure any scoring of the barb
shoulder is removed. Removal of any shoulder material in reasonable
sharpening of the barb should be accomodated by the hose as it
settles on the barb shoulder. Has anyone attempted to repair a
damaged barb shoulder by soldering/brazing additional material back
onto the barb shoulder and then shaping to the original dimensions?
Kirby/Roger B./Richard D./George B./… your comments
please. Removal of old hose with the soldering iron blade seems to
be the least damageing to the Barb-shoulder. Best, JW

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

Dr.Quail wrote:

Has anyone attempted to repair a damaged barb shoulder by
soldering/brazing additional material back onto the barb shoulder and
then shaping to the original dimensions? Kirby/Roger B./Richard
D./George B./… your comments please.

I have repaired damaged barbs by simply filing off metal. The barb
is plenty large enough to effect a seal provided there isn’t a notch
in it. As long as the notch is reasonably small, you can just smooth
the surrounding area until it’s gone. The OD of the barb is hence
smaller, but it still works.

Best fix of all, though, is to not damage the barbs in the first
place. I’d recommend that anyone doing this job the first time
remove the old hoses from the rail first, because the rail is hard
steel and more difficult to damage. Once you get the hang of it,
then start on the injectors themselves. The injector body is softer
and easier to damage.

– Kirbert

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

In reply to a message from Kirbert sent Thu 22 May 2008:

I found the easiest way to remove fuel hose from the barbs
on the fuel rail and associated fuel connections is to heat
the ferrule and hose at the connection until the hose
becomes soft enough to pull off or catches fire, whichever
occurs first. The heat doesn’t seem to bother the metal
parts. A propane torch like those used by plumbers is
suitable for this purpose.

This method avoids the possibility of nicking any of the barbs.

The cup shaped ferrules function as compression fittings.
I’m not sure how the little saucer shaped washers on the
fuel rail to injector connection contribute to sealing the
hose to the barb, if they do.–
The original message included these comments:

Best fix of all, though, is to not damage the barbs in the first
place. I’d recommend that anyone doing this job the first time


Rogers Abbott, British car fanatic
Edmond, Oklahoma, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

Rogers Abbott wrote:

I found the easiest way to remove fuel hose from the barbs
on the fuel rail and associated fuel connections is to heat
the ferrule and hose at the connection until the hose
becomes soft enough to pull off or catches fire, whichever
occurs first. The heat doesn’t seem to bother the metal
parts. A propane torch like those used by plumbers is
suitable for this purpose.

Sounds like a plan to me! Any chance that you’ll melt the lining of
the hose and apply a permanent rubbery coating to your barbs?

The cup shaped ferrules function as compression fittings.

The ones that are crimped do. The ones you can just spin around the
hose with your fingers clearly aren’t doing much in the way of
compression.

I’m not sure how the little saucer shaped washers on the
fuel rail to injector connection contribute to sealing the
hose to the barb, if they do.

Functionally, I’d be confident in replacing all of these things with
flat washers, something for the hose to bump into as you’re pushing
into place. All you have to do is see the industrial versions: push-
on hoses that handle several hundred psi of hydraulic fluid, and the
cupped washer is flimsy plastic – and square-bottomed, not saucer
shaped. It quickly becomes clear that all this talk about the
ferrule being necessary to apply some compression to the hose is
hooey.

I wouldn’t feel nearly as good about leaving the ferrules off
altogether, because then you could push the hoses on too far – and
you could do this later after the entire set of injectors is in place
and you just lean over the engine. You need something that acts as a
stop when installing the hoses. And the saucer shape helps hide the
ratty-looking end of the hose.

– Kirbert

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

In reply to a message from Kirbert sent Fri 23 May 2008:

I tried the soldering iron and the blowtorch, both work well.

Just be careful with burning fuel hose as some versions have
fluorolastomer content, and this is highly dangerous when
burned, producing both toxic fumes and hydrofluoric acid in
liquid form. The only way to do it safely is with good
ventilation and gloves, then treat any burnt material as
harzardous to the touch.–
1990 XJ-S V12 Convertible, Glacier White, 59K miles
Santa Clara, CA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

Mark H,

Cool. Wasn’t it hydroflouric acid back in school chemistry class that would
eat through glass? One of the nastiest acids out there. It was strange
because it was stored in a plastic bottle. All the other acids were in those
nice ground glass bottles.

Now I know how to get that acid I was looking for in my next bank robbery,
(to fund my V12 build you understand), without leaving a paper trail for the
investigators.

Headlines: “Police Solve Disolved Vault Case. Suspect caught burning fuel
hose to fund V12 habit.”

:wink:
Mark-----Original Message-----

Just be careful with burning fuel hose as some versions have
fluorolastomer content, and this is highly dangerous when
burned, producing both toxic fumes and hydrofluoric acid in
liquid form.

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

In reply to a message from Mark Eaton sent Mon 26 May 2008:

Very nasty. One chemist told me it’s the only compound that
they are afraid of.–
1990 XJ-S V12 Convertible, Glacier White, 59K miles
Santa Clara, CA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

G’day Mark,

I believe that hydrofluoric acid is also a by-product of the R12 aircon gas,
being a hydrofluorocarbon (HFC), when it combines with water vapour one of
the products is the acid. One of the reasons that the aircon circuits are
evacuated to boil off water vapour before the system is re-gassed. R134a,
being a CFC, is not as problematic.

Hydrofluoric acid attacks glass by dissolving silicon dioxide, a major
component of most glasses. It is used in the production of many diverse
polymers.

Regards,
Jeff Watson.
Sydney, Oz.
1995 V12 X300

Mark H,

Cool. Wasn’t it hydroflouric acid back in school chemistry class that would
eat through glass? One of the nastiest acids out there. It was strange
because it was stored in a plastic bottle. All the other acids were in those
nice ground glass bottles.

Now I know how to get that acid I was looking for in my next bank robbery,
(to fund my V12 build you understand), without leaving a paper trail for the
investigators.

Headlines: “Police Solve Disolved Vault Case. Suspect caught burning fuel
hose to fund V12 habit.”

:wink:
Mark

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

In reply to a message from SD Faircloth sent Thu 22 May 2008:

[V12-engine] FI Hose Ferrules…Functional or just pretty ?

Yes David, I fully support your explication.
Nice work, indeed it is adviced to (re-)use’em when they’re OEM
fitted. Its a safety measure against leaks and edge enlarging.

One critical detail that comes up to me is, and I’ll try to provide
some pictures next week, these ferrules compromise a bit a straigth
view on whether the new FI-hoses are correctly fitted to the end of
the rail. That should be a small caution.

I’ve luckily experienced this before engaging the engine,
the day I refitted this FI-rail assembly.

Great work, thanx, have a nice week all ;-)–
The original message included these comments:

The question routinely comes up on J/L, and I get my share of
personal e-mails also, on whether these things actually serve a
3) More importantly…They Do Work.
Perhaps a bit hard to visualize with words. One of these days, I’ll
post my diagrams on the web site.
SD Faircloth


Best regards, Harry '85 European HE, Belgium.
Brabant, Belgium
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

In reply to a message from Mark H sent Fri 23 May 2008:

Hi Mark,

haaaa hydrofluoric acid toxic fumes,
thats what itches the nose and eyes.

Nothing smells better in the morning :wink:

I’d use a good adjustable temperature Weller soldering station,
and setting it for +150�C. No more is necessary.

Fluorolastomer contents - aka VITON - where not yet all to common
back those days when our Jags were developped.

Nowadays Dupont is releasing the F200 Barier FI-hose,
a combination of all the best components like Viton outer wall,
Hypanol inner, Kevlar woven intermediate mantle, etc…etc…

Thanx for the advice ;-)–
The original message included these comments:

Just be careful with burning fuel hose as some versions have
fluorolastomer content, and this is highly dangerous when


Best regards, Harry '85 European HE, Belgium.
Brabant, Belgium
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !