Jaguar XJ-S. Manual - part 61

 
 

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Note that there are a few places on the XJ-S where one end of a hose is a push-on connection and the other end requires 
a clamp.  The push-on hose is suitable for these applications; it can be reliably clamped on suitable barbs. 

The Weatherhead cloth surface hose is more expensive than the rubber surface: $2/foot.  Don’t be intimidated by the 
fact that Jaguar wants many times that much for their “original” hose; it’s no better, and it’s arguably not as good.  
Weatherhead is one of the most respected names in the industrial hose business. 

Another good reason to be shopping at the industrial hose supplier is that you can buy this Weatherhead H100 hose in 
1/2” size.  There are a couple of 1/2” fuel hoses in the trunk of the XJ-S, but there aren’t many auto parts stores that 
carry 1/2” fuel hose. 

Of course, you can buy fancier hose.  Bill Fernandez says, “There is a lot of stuff available out there, aero hoses, rubber, 
etc.  High quality cloth braided German fuel injection rubber hose is what I ended up using.  This is the same 
equipment used in BMW and Mercedes, they don't go bad period.  I have a 1975 CSi (BMW) with the original cloth 
braided hoses with 325k original miles and not a single leak or hint of gas yet. 

“The H.E. Bosch injectors are designed to use slip-on rubber injector hoses.  The areo style will require lots of 
modification to both the injectors and the fuel rail to get them to work.  The areo stuff is very pricey and just not worth 
it aside from looks.” 

 

FUEL HOSE CLAMPS:  Some fuel line connections, especially on earlier cars, came with crimped collars that 
compressed the hose against the barb.  If you remove a hose with a crimped collar, you can replace it with new hose 
with a clamp -- provided you use the correct type clamp.  If you live in the US and walk into an auto parts store and ask 
for a hose clamp, you will be handed a stainless steel band with a series of angled slots through it and a worm screw 
attached to one end.  These “aircraft type” clamps are excellent -- for lines about 3/4” in diameter and larger.  Although 
they do sell small clamps in this style, they do not work well on hoses as small as the fuel lines on the XJ-S.  There are 
simply too many “corners” within that circle as it is snugged up, and although it may seal at first while you’re looking it 
may leave local areas that aren’t securely compressed against the fitting and will start leaking later when you’re not 
looking. 

If you live in the UK and ask for a hose clamp, you might get a “Jubilee” clamp or something similar.  These are also 
stainless steel worm screw clamps, but instead of angled slots in the band it has little raised lips for the screw to engage. 
 These are better than the US aircraft type clamps on small diameters, but still not good. 

To assure a good, reliable seal, you’re going to need some clamps that securely compress the hose onto the fitting 
uniformly all the way around.  While the worm screw types are not recommended, there are several other types that will 
work fine.  Many auto parts stores sell “EFI hose clamps”, which consist of a steel band with a small screw and nut that 
draws it tight.  They come in various sizes, and you need to carefully select the size you want; these type clamps will 
only fit the size hose intended, you cannot just keep screwing them down smaller like a worm screw clamp.  
Unfortunately, you’re not likely to find these type clamps in stainless steel, so it is advisable to carefully apply anti-
seize compound to the threads on that tiny screw if you ever want to get it loose later. 

Sometimes EFI clamps are offered in a package with the hose; make sure you have suitable clamps on hand or can buy 
them separately before buying EFI hose without the clamps.  Jim Taylor says, “I replaced the originals on my (then) 16-
year-old '76 XJ12C.  I obtained two Volvo FI hose replacement "kits"  (part number 273680-9).  Each kit contained the 
appropriate number of short rubber hoses and neat little black painted hose clamps (not worm gear type) for a Volvo six 
cylinder car.  This fix didn't cost very much.  My receipt (dated 3/4/92) shows I was charged the grand sum of $6.11 per 
kit.”  Of course, similar kits may be available from other car makes as well. 

John Ashcroft, who lives in Australia, says, “If you have screw (worm drive) clamps and have an engine fire, the 
insurance company will not pay.  You have to have EFI clamps on fuel lines.” 

There is also a type of clamp that works similarly to the EFI clamp described above, except that it has two loops of wire 
in place of the steel band.  These seal pretty well, but they’re not very pretty and they really mangle the hose.  They 
don’t seem to come in stainless steel either. 

 
 

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Greg Price says, “The Series III XJ6 has some nice fuel injection hose clamps, and my local Jag tech recommends 
Mercedes fuel injection hose clamps.” 

Stefan Schulz says, “Here in the UK, Farnell offer stainless steel hi-torque hose clamps which are The Biz.  Highly 
recommended.  Farnell Industrial are on telephone [+44] 113-2636311.”  Schulz adds that he does not recommend the 
fuel injection clamps from a Volvo. 

Tom Mackie says, “I find most conventional "clamps" to be a little unsightly.  So..  There is a clamp used in the repair 
of shop air hoses as well as on oxy/acetylene hoses (if that's not a high fire hazard application, I don't know what is).  
These clamps do not have a screw/nut on them.  They are a single usage item. They are a formed metal band, with an 
outward flare/dimple/nipple (I have no idea what to call it) on each side.  These simply slide over the hose, are placed 
into position, then using pliers, these nipples are squeezed, compressing them, which in turn tightens the clamp.  No 
screw/nut sticking out, getting in the way, cluttering appearances etc. Definitely not self loosening.  Removal is with 
side cutters.. Just snip off one side and bend it open.  These are cheap.. so making them disposable is not a big deal.  
This I would use on the injector end. 

“I was considering another crimp style, but for the fuel rail end.  There is what I'll describe as a "cup" shaped unit, 
which I believe is sorta an aeroquip fitting.  I have to confirm this yet, but I believe you could use any hose with the 
appropriate size "cup" and have it crimped into place.  The minor catch is that you either need the special tool which 
applies pressure to about 6 locations at the same time, or you have the fittings shop do it by taking them the fuel rail.  
These are semi-permanent, and removal is with a hack saw, which destroys the hose.  This is why I'm thinking of using 
these on the fuel rail side, and the removables on the injector side.  Again, no screws sticking out, etc.  Nice-n-neat.” 

Note that the problem of worm screw clamps causing leaks is not unique to the EFI fuel system.  One should also take 
note of the types of clamps used on the fuel tank vent system, the power steering hoses, the transmission cooler hoses, 
and just about anywhere else that small diameter hoses are clamped.  Leaks at some of these locations may be less 
disastrous than a fuel system leak, but you’d still rather not have any leaks. 

 

CLAMPLESS HOSE CONNECTIONS:  The section above describes what clamps to use on fuel hoses.  Now let’s 
discuss not using them!  There are two types of hose barb used in the fuel systems on the XJ-S, and one of them must 
be clamped while the other should not be clamped. 

DO NOT CLAMP

CLAMP REQ'D

 

Figure 13 - Fuel Hose Barbs 

With the barb shown at left, the hose is installed by merely pushing it onto the barb.  It works kinda like a Chinese 
finger trap; the hose slides on easily, but if you try to pull it off it grips onto the barb and won’t let go.  These fittings 
typically come with a dished washer or cup that must be slid into place before pushing the hose on, but these items do 
nothing more than hide the cut end of the hose to make the installation look neat.  Hydraulic hose shops have push-on 
fittings with flimsy plastic dished washers. 

Proper use of a hose clamp requires the smooth cylinder of the type shown at right for the clamp to compress the hose 
against.  If a clamp is applied to the barb shown at left, it will compress the hose against the points on the ridges and 
possibly damage the inner liner of the hose.  There are clampable barbs that have a series of small ridges in this 
clamping area, presumably to help ensure a reliable seal, but they are usually rounded and easily distinguishable from 
the large, toothy grips of the clampless barb. 

 
 

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Believe it or not, the non-clamped type provides a much more reliable seal.  This is apparently because it allows the 
rubber hose to flex and seals more securely as it does, whereas the clamped connection will often start to leak as soon 
as any pulling or twisting is involved. 

Typically, you will know which type you’re dealing with before removing the old hose by looking at what’s on there 
from the factory.  If there’s no clamp, it’s the type that doesn’t use a clamp.  If it’s the type that needs a clamp, there 
will be some form of clamp -- or a cup-shaped piece of metal that is “swaged” or “crimped” onto the end of the hose to 
compress it onto the barb.  The decorative cups on the non-clamped barbs sometimes look similar, but it is obvious that 
they are not swaged; in fact, you can spin them around with your fingers. 

The problem, of course, with relying on the existing situation as an indication of barb type is that someone may have 
gotten in there before you and added clamps where there shouldn’t be any. 

Note that you may have a mix of clamped and clampless fittings.  The early D-Jetronic cars use clamps everywhere.  
John Ashcroft says that his ’80 needs clamps on the rail but not on the injectors.  On the author’s ’83, the entire 
injector/rail assembly uses clampless fittings, but the connections at the fuel cooler still require clamps. 

Regarding pressure ratings and the security of push-on connections:  A shop frequented by this author has a tester, and 
in their spare time they test things to failure just for grins.  The 5/16” cloth-surface push-on hose described below was 
tested, installed as intended on a push-on fitting.  It held to 1200 psi, and then the hose ruptured near the end of the 
barb.  The push-on connection never leaked or came apart. 

 

INJECTOR HOSE REPLACEMENT:  The hoses most likely to need replacing are the short hoses from the rail to the 
injectors themselves, probably due to exposure to heat or the corona of the spark plug wires. 

This job is a cinch.  If you’re doing all 12, you don’t even need to remove the injectors, but you’ll probably want to 
remove it to save your back and also to replace the injector seals at the same time.  Either way, you will need to 
depressurize the fuel system.  You will be spilling a little fuel, so take suitable precautions.  Disconnect the inlet and 
outlet lines to the rail, and remove anything that goes over the rail. 

Measure the lengths of the hoses.  On the D Jetronic cars, all 12 are the same, while on the Digital P cars the rear 10 are 
all the same and the front 2 are longer.  You don’t want them too long because the rail may hit the hood or the 
kickdown switch.  Craig Sawyers says, “I measured the length of the fuel injector lines when I disassembled them to be 
close to 2 inches - so that is what I cut the new ones to.  Well, that is a tad long.  I only discovered that when I bolted 
the throttle cable back on, and the kickdown switch plate sat at a jaunty angle, and wouldn't go level.  If I were doing it 
again I'd cut the hoses to 1.75 inches and give everything a little more clearance.”  Rod Wright agrees:  “I also cut my 
hoses 2" long when I replaced them.  In addition to the interference with the kickdown switch bracket, the bonnet was 
making contact with a point on the fuel rail about 1" aft of the 1B injector hose barb.  I noticed matching shiny spots on 
the rail and bonnet caused by the slight movement of the engine.  Not wanting to chafe a hole in the fuel rail, I cut new 
hoses 1.75" long.  This alleviated both problems.” 

Well, maybe.  Peter Cohen says, “I found a post that said that 2" is too long, and one, possibly two people said to make 
them 1 3/4" long, so that's what I did.  Everything went well until it came time to re-install the metal fuel line that runs 
from the left side regulator to the left rear of the fuel rail.  That's when I discovered that the thermal valve (EAC5086) 
was sitting lower than before, and I couldn't quite get out the middle screw that sits directly below the thermal valve and 
secures the fuel line and air injection rail to the manifold.  Somehow I managed to snap off the plastic vacuum port on 
the thermal valve.  I don't actually know how or why it broke, only that it went flying, so gluing it back on is not an 
option.  I guess I'll be buying a new valve. 

“Anyway- 1 3/4" is too short if you are going to fully seat your hoses. 1 7/8" must be the right spec...” 

After establishing what length you’ll be making the new hoses, cut all twelve old hoses through the middle.  Any fuel 
remaining in the rail itself will dump out, so you might want to choose a suitable hose to cut first and quickly aim it into 
a jar.  You might then try cutting a hose at the other end of the rail and blowing through it to clear out as much fuel as 
possible.  After cutting the hoses, lift off the rail, leaving the injectors in place. 

 
 

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Remove the pieces of the old hose from both rail and injectors.  If there are crimped metal collars (early D Jetronic), 
you will need to cut through one side of each collar and spread it a little.  On the later style clampless assemblies, don’t 
lose the dished washers.  Try to do as little damage to the barbs themselves as possible.  The basic idea is to use a 
straight razor blade -- a boxcutter blade or utility blade, whatever -- to “shave” down one side of the hose, cutting just 
deep enough to slice through the reinforcing cord inside the hose but being careful not to cut so deep as to penetrate the 
inner lining of the hose and contact the metal barb inside.  Cut too shallow the first couple of times just for practice; you 
can always cut deeper, but once you’ve cut too deep you’re faced with barb damage.  Once the reinforcing cord is 
severed -- possibly two or more places around the barb -- the hose can be pulled off. 

The problem, of course, is the decorative dished washers get in the way.  You can only slice so far down the side of the 
hose before the blade hits the washer, leaving the last 1/8” of the cord uncut.  It’s trying to get that last part cut, using a 
corner of the blade or whatever, where frustration sets in, and the frustration can result in damaged barbs.  Richard 
Fields says, “I used an X-acto knife (available at any hobby shop) to remove the hoses, after fighting them with a razor 
knife.  The X-acto blade I used was shaped like a cats-Jaguar?-claw and could get in behind the washers very easily.  It 
made cutting the hoses off a snap!” 

Note that while the clampless barbs all are similar in configuration, the ones on the injectors are made of much softer 
metal than the ones on the rail. 

If the barbs get a little dinged up, believe it or not they can usually be repaired quite effectively.  The trick is to make 
sure there are no “notches” in the edge of each ridge, so that the edge of the ridge contacts the inside of the hose all the 
way around to form a leakproof seal.  If there’s a notch, you can grip the barb gently with a standard pair of pliers while 
you rotate the injector (you probably need to remove the injector from the engine to do this properly) so that the teeth 
on the pliers scrape off the edge of the ridge all the way around until the notch is cleaned up.  You still don’t want to 
use a clamp on this hose connection unless you had to clean the ridges completely off to get rid of notches -- in which 
case you probably should spring for a new injector. 

Others suggest not using a razor knife at all.  John Ashcroft says, “Used a electric soldering iron to burn the old hoses 
off of injectors with no damage to barbs.”  Ken Gray elaborates:  “You poke the hot tip of the iron into the fuel line just 
above the top barb and push it down the length of the fuel hose and into the seemingly useless cupped washer at the 
base where you just work the tip around a bit to completely severe the hose.  The whole process takes a few seconds 
due to the very hot tip of the weller.  You can grab hold of the barbs immediately after hose removal and they are barely 
warm.  I would not use any other method now as the soldering iron works perfectly without any damage to the barb or 
internal platics of the injector.  You do however need to use the correct soldering iron; I ended up using a Weller 
electric iron which seems to have a temperature control in the tip.  I must also say that I have not been able to reliably 
regenerate the tip for soldering purposes.  This is not a problem because the tips are readily interchangeable.” 

Cut suitable 8mm or 5/16” (7.9mm) into suitable length pieces.  For the Digital P, make doubly sure that all the hoses 
for the rear ten injectors are the same length; different lengths can cause problems with the clampless barb connections. 
 Install the pieces of hose onto the rail first; if the rail has clampless barbs, remember to put the dished washers in place. 
 Position clamps or dished washers (whichever is appropriate) onto the injectors, and then push the entire rail down 
onto the injectors one bank at a time.  On the Digital P, you can leave the 1A and 1B hoses alone until last.  Tighten 
clamps if you have them; if you have clampless fittings, pull upward forcefully on the rail to help the hoses establish a 
good grip on the barbs.  Reconnect the fuel inlet and outlet, and then turn the ignition on for two seconds at a time for 
several cycles so the fuel pump can repressurize the system.  Start it up and check for leaks. 

 

HOSE ASSEMBLY REBUILDING:  Many of the lines (fuel, power steering, etc.) in the Jag consist of metal tubing 
with threaded connectors and a short length of hose in the middle somewhere, all sold under one part number.  When 
it’s been in there too long and has dried up and started leaking, the section of hose can easily be replaced with suitable 
hose along with suitable clamps.  It is suggested that before you cut the original hose off, you place measured marks on 
the tubes on either side of the hose so that when you reassemble, the same overall length can be established.  You 
should also put alignment marks, so the new assembly won’t be twisted.  Finally, if the hose is within sight of the 
exhaust system or other hot parts, it might be better to wrap it with some aluminum foil to prevent the radiant heat from 
cooking the new hose.