Jaguar XJ-S. Manual - part 128

 
 

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New tar stuff would be good, but other methods of insulation would also work.  You can wrap it with foam strip 
insulation, or you can even spray Great Stuff around it and let it set up in a clump.  You can carefully cut a piece of 1/2 
pipe insulation (looks like a foam tube slit down one side) to fit, wrap it around and tape or strap it in place.  Just make 
sure that that little coil is as cold as the pipe (which is cold!), not as hot as the engine. 

 

REFRIGERANT LEAKS:  Michael Minglin says, “A possible solution is a refrigerant additive available from Cryo-
Chem Int’l at 1-800-237-4001.  It is called Cryo-Silane and reportedly seals small refrigerant leaks, without clogging 
the system.  It is guaranteed to seal and hold for one year any a/c system that takes longer than six hours to leak down.  
As I said I have not yet tried it, and it isn’t cheap, but this may be the answer to small hard to find leaks. 

“On the matter of hard to find leaks, with the a/c service gauges hooked up it is impossible to find leaks in the service 
ports or valves.  If your mechanic cannot clearly show you the leak, have him disconnect his service gauges and check 
the the service port valves before starting to change out expensive hoses and parts.” 

 

HOSES -- BARRIER VS. NON-BARRIER:    How do you tell what type hoses you have?  With this author’s ’83, the 
two low-pressure hoses were non-barrier and the high pressure vapor hose was barrier -- probably indicating earlier 
service work.  The two large non-barrier hoses had a cloth surface -- black, but reportedly red became standard later on. 
 Barrier hoses, on the other hand, seem to always have a smooth black rubber surface.  It may say “Barrier” right on it, 
too. 

Barrier hoses are nearly always attached to the metal tubes with a crimped collar.  The high pressure vapor hose on the 
author’s ’83, however, was attached with worm screw clamps -- worm screw clamps with a tang hanging off the side 
that positions the clamp properly over the barb within.  These worked fine on my car, and reportedly work fine in 
general. 

My non-barrier vapor hoses did not have crimped connections, although other non-barrier hoses may have.  If a hose 
connection is crimped, the crimped collar is usually steel.  My hoses had steel tubes with aluminum collars, and the 
collars had a big hex on the outside.  These collars were jammed up against a smaller hex on the tube itself.  This whole 
thing is a threaded hose connection. 

The large aluminum collar has a very coarse left-hand thread on the inside that threads onto the outer surface of the 
hose.  In the small end of the aluminum collar there is a very fine right-hand thread that the steel tube screws into.  The 
end of the steel tube, the part you can’t see, has a long  smooth taper followed by fine threads right up to the underside 
of that small hex.  The collar is threaded onto the outside of the hose while the pipe is threaded into the center, jamming 
that taper into the ID of the hose and compressing it within the sleeve.  Very secure; in fact, you’ll probably have 
trouble getting it apart.  You need to hold the hose itself and the pipe still (clamp the hose in a vice and use a wrench on 
the small hex on the pipe) and turn the aluminum collar in the direction that should unscrew it off the end of the pipe.  
This is the same direction that will unscrew it off the hose, so turning the collar in this direction will pull the tapered 
end of the pipe out of the hose. 

That all may have seemed like useful info, but it’s probably not.  The R-12 hose these fittings were designed to work 
with is no longer manufactured (although there are generic hoses that will work just as well, if you feel the need to 
rebuild an R-12 hose).  The barrier hose will not work with these threaded hose connections. 

The fourth hose on my ’83, the small section of hose on the liquid line, was completely different from the other three in 
all respects.  It was a funny type of hose with an inner layer of what appeared to be plastic tubing, a layer of strong 
cloth, and an outer surface of hard plastic.  It was crimped onto fittings, but it was an unusual type of crimp, probably 
proprietary.  The barb is brazed onto the tubes, and the crimp ring was formed anchored to a groove in the barb so it’s 
not removable.  The part number for the entire hose assembly is CAC.5596.  It is unknown whether this was a barrier 
hose or not, but it didn’t really matter; by the time I looked at it, it was clearly in need of replacement. 

 

 
 

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HOSE REBUILDING:  If you need to replace barrier hoses because yours are old and rotten, read on.  If you need to 
replace non-barrier hoses, you should go ahead and convert to barrier hoses -- and that means you should flip to page 
520. 

There are four hoses on the freon circuit in the XJ-S.  Besides the three obvious large ones up top, there is a small one 
on the liquid line below the upper right radiator hose.  If you’re planning to replace hoses, you might as well plan to 
replace all of them. 

Most A/C shops claim to be able to rebuild hoses.  Some hoses are more difficult to rebuild than others, and the more 
difficult ones require a special crimp tool that, while reasonably priced as shop tools go (no power, hand operated), was 
introduced later.  If the A/C shop is working with the older style crimp tools, it cannot rebuild some hoses.  The usual 
result is that they will cut the fittings on your old hose and braze on sections of tubing that their tools can crimp a hose 
onto.  This looks like crap when done, but it does work. 

If the tubes on your hoses happen to be aluminum, only the newer tool will work, since brazing is out and the older tool 
will crush the tube.  If the A/C shop doesn’t have the newer crimp tools, they will claim that the hose cannot be repaired 
and order you a new one from Jaguar and collect their markup on the part. 

How does any of this apply to the Jaguar?  It probably depends on the vintage.  This author’s ’83 had non-barrier hose 
assemblies with steel lines with threaded hose connections (as described on page 520), so rebuilding with barrier hoses 
required cutting and brazing.  I suspect later XJ-S’s came with aluminum tubes with barrier hoses with crimped 
connections, so brazing should be neither possible nor required to rebuild. 

Peter Cohen provides these words on rebuilding hoses:  “Take the whole car to the shop, not just the hoses.  A/C hoses 
have almost no ability to twist, and since all but one hose on the V12 have angled connections the odds are that the hose 
shop will not get the angle right unless they assemble it on the car, put paint marks on the pieces to show the exact 
positions, and then take it back into the shop to crimp it.  The shop I used was reluctant to even make the hoses because 
of all the come backs from wrong angles.” 

Actually, you can avoid that problem.  The angles at which hoses are crimped to fittings is only a concern when there 
are angled fittings crimped to both ends; the relationship between the two ends must be correct or you’ll have to twist 
the hose to get things to line up.  If there’s an angled fitting at one end only, there’s no problem; you can simply rotate 
the entire hose to fit.  Of the three larger hoses on the XJ-S, the high pressure hose from the compressor to the 
condenser and the low pressure hose from the fuel cooler to the compressor each have a straight fitting on one end, so 
there is no problem.  The only large hose with angled fittings at both ends is the hose from the firewall to the fuel 
cooler, which has 45° fittings at both ends.  Solution: rebuild that hose with a 45° fitting at the firewall end and a 
straight fitting at the fuel cooler end.  It will fit better this way. 

Assemble these parts to attain an overall length of 23”, measured in a straight line from end of tube to end of tube (a 
corner on the end with the 45°).  This is about 1-1/4” shorter than the OEM hose that came on this author’s ’83.  The 
length is somewhat critical, more critical than the lengths of the other two hoses.  Ideally, find a way to either measure 
or trial fit to find the correct length on your car, since your engine may be positioned within the engine compartment 
differently than mine.  Resist the compulsion to make the hose a bit longer “just in case”, because too long is a real 
problem here. 

You could forget about crimping and rebuild your own hoses using clamps -- if you have crimped connections to begin 
with.   Tony Bryant says, “I went to my local air con place, picked up 2 metres of R134a rated barrier hose in the 
correct diameter for <$10, went to my local hydraulic hose place (who wouldn't/couldn't crimp the aluminium fittings), 
and picked up some top quality stainless hose clamps.  These are high pressure items, not worm gear clamps, and use a 
bolt and cylinder arrangement to forcefully clamp.  They also have a continuous band.  Each <$5.  I replaced the high 
side hose using these items, after carefully cutting the old hose off the aluminium fittings.  Holds pressure perfectly.” 

Bryant lives in New Zealand where apparently you can get good clamps.  Unfortunately, here in the US finding clamps 
such as those he describes can be difficult.  Try at a marine store; they offer something called a “t-bolt clamp” which is 
obviously an excellent item, but unfortunately you probably won’t find one small enough for this job.  Of course, EFI 
clamps available at auto parts stores would work except that you probably won’t find one big enough for this job.  In 
general a worm screw clamp won’t work because the slots in the band dig into the rubber surface of the hose and 

 
 

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prevent you from tightening it far enough -- but there are better worm screw clamps that don’t have the slots all the way 
through the band but rather just impressed in the outer surface so the inside surface is smooth.  Worm screw clamps 
also tend to have trouble applying consistent compression under the screw itself, but better ones are available with a 
shield around the inside to address these problems. 

Even if you have a shop rebuild your three larger hoses, you will want to replace the small hose in the liquid line 
yourself.  It’s just too difficult to remove that assembly from the car.   Once you get the old hose and crimp rings off, 
you can install a new hose onto the barbs with clamps -- but getting the old hose and crimp rings off is easier said than 
done.  Cut the hose in the middle, disconnect one end of the line from the dryer and remove that piece from the car and 
carefully work on the hose attachment on the bench.  Grind through one side of the crimp ring, being careful not to cut 
so deep as to nick the barb underneath.  You’ll probably find things easier if you go ahead and grind through the crimp 
ring again around on the other side.  This crimp ring is retained in a groove at the end farthest from the hose, which 
means you will need to use a cutting wheel down within that groove to fully cut through the crimp ring -- but 
alternatively you can just cut the crimp ring all the way around 1/8” from that end and leave that tiny portion in place, it 
won’t hurt anything.  When you’ve figured out how to get the crimp ring and the hose off leaving a clean, usable barb, 
then repeat the process on the end you can’t get out of the car. 

Doing this job yourself, in place, also eliminates any worries about getting the length or alignment correct. 

If you must get the liquid line out of the car, cut the tube at the RR corner of the engine compartment near the drain 
from the wiper motor compartment.  Then remove both halves of the line from the car, much easier as separate pieces.  
While you’re having the shop crimp a new hose on, have them braze fittings onto the ends you cut so you can screw 
them back together with an O-ring.  Make sure to cut within a suitable straight section of the line, since they can’t braze 
fittings into a curved section. 

The high pressure vapor hose assembly is 1/2”, so the hose that fits it is 13/32”.  The low pressure hose assemblies are 
5/8”, so the hose that fits them is 1/2”.  The liquid line is 3/8”, so the hose that fits it is 5/16”.  Don’t ask me to explain 
that. 

 

HOSE VS. THROTTLE:  Peter J. Havas provides a warning:  “If you’re not careful, and I wasn't, you can push the low 
pressure tube down and it will foul the left side throttle arm from the spindle, and lock open in traffic!  Neat, huh?  Use 
a wire-tie to secure the hose to the diagonal brace for safety.”  Please take this warning seriously; Havas isn’t the only 
XJ-S owner who has found his throttle jammed wide open due to the hose fouling the left side throttle linkage. 

Tying the hose to the diagonal brace would seem to be the obvious solution, but when working with the hose that goes 
from the firewall to the fuel cooler remember that the firewall doesn’t move and neither does the diagonal brace -- but 
the engine does move around on its rubber mounts.  Strapping the hose to the diagonal brace would seem to be an 
excellent plan for making sure the engine motion doesn’t stress the fitting at the firewall, but be sure to leave enough 
flex between there and the fuel cooler for engine motion.  If the hose assembly is short enough, it may be preferable not 
to tie the hose to the diagonal brace. 

The hose being too long, as this author’s OEM hose was, probably aggravates the fouling problem.  Too long makes it 
want to loop up high, but then the hood is closed on it -- forcing it both downward and contorted.  If yours loops up like 
that, you might want to try just pushing down on the high part of the loop with your hand and see what happens -- and 
remember that the loop changes shape as the engine moves around on its mounts. 

Perhaps a far better method of keeping the hose from fouling the throttle linkage would be to provide a shield over or 
alongside the throttle linkage at this point.  A small bracket could be fabricated from sheet metal to form a small shelf of 
sorts that the hose can rest on and slide around on with engine movement and be absolutely prevented from getting into 
the linkage.  Such a bracket could be designed to be installed under the heads of the two upper screws holding the 
elbow to the rear of the LH intake manifold -- see Figure 25.  This can be fabbed from any sturdy sheet metal. 

 

 
 

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The sheet metal should be folded about 20° along the vertical dashed lines to form a zig-zag so the shield will bolt 
down under the bolt heads which are not at the same level.  It should be folded 90° towards the front of the car along 
the lower horizontal dashed line to form a flat area for the hose to sit on, and then fold the edge downward along the 
upper horizontal dashed line to form a little lip so there are no edges of metal to cut into the hose.  If you’d prefer, you 
can omit these last folds and just cut the panel off at the lower dashed line and slit a piece of plastic tubing and slip it 
onto the edge to form a surface for the hose to ride on.  This would require a bit stiffer sheet metal, since the folds add 
stiffness. 

Or, perhaps a better idea, a shield could be designed to be installed sandwiched between the elbow and the manifold 
with an additional EAC2650 gasket.  The gasket itself could be used as a template to fab the lower portion of this 
shield. 

When done fabbing and installing a shield, be sure to dial the throttle back and forth to check for unobstructed motion 
when done. 

If Jaguar had decided to address this concern, it would have been a simple matter to design the plate holding the linkage 
at that corner to include this foul-prevention feature. 

 

HOSE REMOVAL:  On this author’s ’83, the hoses on the low pressure portion of the circuit (either end of the fuel 
cooler) has nuts on each end with a 27mm (1-1/16”) hex on them.  Presuming you don’t have open-end wrenches in 
that size, you’re going to be using the monkey version. 

Problem: the connection at the firewall is gonna be a bear to get a monkey wrench on.  It calls for a crowfoot wrench -- 
but you’re not going to find one of those in 27mm or 1-1/16” easily. 

The solution is as close as the local hardware store.  It’s called a basin wrench.  Now, here’s what you’re gonna do: 
you’re gonna peer down into the area under the balance pipe where this connection is, then you’re gonna go down to 
the hardware store and look in the plumbing department at a basin wrench, and you’re gonna say, “Man, I gotta get me 
wunna those!”  And not just for this job, either; a basin wrench is quite obviously one of those tools you’ll wonder how 
you ever got by without.  It’s sort of a crowfoot version of a pipe wrench; it has a pair of jaws that will grip when you 
turn it in one direction, no matter what.  It’s quite handy at removing sensors, too. 

There are three types.  One has a shaft perhaps a foot long with a T handle at the top; the jaws at the bottom can flip 
around the end to reverse direction.  This costs about $15.  Another type is the same thing, but the shaft is extendable; 
this costs about $20.  The third kind is just the jaws themselves with a 3/8” square hole so you can use it with your 

Figure 25 - Throttle Linkage Shield