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Jaguar XJ-S Freon Hoses

Freon Hoses

Barrier vs. R-12

There are three separate issues discussed using the same photos, so you get to see them over and over here.

Kirby Palm's 1983 Jaguar XJ-S came with this freon hose:

R-12 Hose w/ Threaded Connections

The first issue is the hose itself.  That is an R-12 hose.  How can you tell?  Because it has cloth on the outside.  Reportedly later R-12 hoses were color coded red, but still cloth.  Those hoses are no longer manufactured, but there is equivalent hose commonly available that is black; they're just not listed as intended for freon.

By the way, that hose has braided metal under the cloth.  You won't be cutting this hose with a razor knife.

Barrier hoses have smooth rubber surfaces -- like this one:

R-134a Barrier Hose

This hose actually says "Barrier" right on it, although it's not visible in this picture.

Most mechanics now agree that it's not really necessary to convert to barrier hoses when converting from R-12 to R-134a.  Supposedly this is because the mineral oil that was used in the R-12 system has permeated the inside surface of the hose and sealed it so R-134a won't leak through it.  Even if it does leak, it's only a few ounces a year, so it's arguably cheaper to just top it off occasionally than fiddle with hose upgrades.  OTOH, it's really not very expensive to haul the three large hoses from the XJ-S into an industrial hose shop and have them build a new set to fit.

Second issue:  The connections between the hose and the end fittings are different.  That barrier hose above is obviously crimped onto the fitting.  The fitting itself is aluminum, but the crimp sleeve is steel.  There is actually a color code used here; this is a crimp for a 5/8" line, and it has that brass tint to it.  The crimp sleeve for a 1/2" line -- such as the high pressure line on this car -- has silver-colored crimp sleeves.

The connections on the R-12 line are a whole different animal:

R-12 Hose w/ Threaded Connections

This is a threaded compression connection.  The tube itself is steel, and hidden within this assembly is a fine thread and then a tapered end.  That aluminum collar has a mating fine thread within the end nearest the small hex, and a big coarse left-hand thread that digs into the outer sheath of the hose itself.

The way to get that thing apart is to clamp the hose itself down in a vice and use a wrench to hold that small hex still.  Then with a big wrench turn that aluminum collar in the direction that would unscrew it from the fine thread on the steel tube.  Since the coarse thread gripping the hose itself is left-hand, turning that direction also unscrews the collar off the outside of the hose.  As you turn that collar, it will pull the tapered end of the steel tube out of the hose.  You'll end up with parts that look like this:

Exploded View of Threaded Hose Connection

Of course, there's no good reason to take it apart.  This coupling cannot be used with barrier hose.  The only way to reuse this fitting with barrier hoses is to saw off the fitting itself and braze on a barb suitable for crimping a hose to.  Since the fitting end is a standard fitting, that isn't worth doing; just install a new standard fitting.  They're usually aluminum, so you save a little weight and get a part that won't rust.

Third issue:  When having these hoses rebuilt with barrier hoses, Palm had the shop change the configuration of the hose that goes from the firewall to the fuel cooler.  The original hose had a 45° fitting on both ends.  Palm had the new hose made with a straight end at the fuel cooler end, and also made the overall length of the hose about 1-1/4" shorter.  Here are two pix of how it fits:


R-134a Barrier Hose

Low Pressure Hose

This looks like it was made to fit -- as opposed to the way the original hose fit, which was all twisted and crammed in there.

There is a second advantage to putting a straight end at one end, and that is that the shop building the hose doesn't have to worry about angles when assembling.  With a 45° at both ends, the fittings have to be aligned properly when crimped; it's hard to twist a freon hose, and the fittings won't slip under the crimps either.  With one end straight, none of this matters.

You can also read all about keeping that hose from fouling the throttle linkage.


 

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