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Jaguar XJ-S. Manual - part 12

LEAKY O-RINGS:  The O-rings available at your local parts store are probably as good as the Jaguar originals --
which is to say not worth a damn.  Whenever an O-ring is encountered during disassembly of the V12, it invariably is
hard and brittle and has long since ceased sealing properly. Viton O-rings are the recommended upgrade, although you
might not find them in your local auto parts store; you might need to visit a good industrial supply place to find them.
They are often brown to distinguish them from normal O-rings, but they can also be found in black or any of several
other colors. The price is always an indicator, though; they cost several times as much.

Andy Hutchinson reports: “Looked at my book today. It would seem the choice of "elastomers" (posh for rubber) is
Nitrile, Flurocarbon or Flurosilicon. Viton is Flurocarbon. Excellent hot and chem resistant. Not so good cold.
Flurosilicon is good at both ends but not very tough (fixed surfaces only). Nirtrile is a good all rounder and I suspect
the standard material. Rubber, silicone, neoprene, etc. are dogs.” As long as you’re not building Space Shuttle solid
rocket boosters, that lack of cold performance of Viton may be acceptable; on the Jag V12, it’d be preferable to leak
only in freezing weather than to leak all the time!

Viton O-rings can be ordered from McMaster-Carr (page 709).

LEAKY BANJO FITTINGS: Banjo fittings require two sealing washers. The copper washers used to seal the banjo
fittings at the back end of the tappet blocks are really thin, only about .010” thick. This is too thin for reliable sealing,
so chances are pretty good that these banjo fittings will leak right after assembly.

If your local auto parts store has a rack of red cards titled “Help!”, it probably has a package of sealing washers that are
the correct diameter for these fittings but a lot thicker: Part number 66272, labelled “Brake Hose Bolt Washer”. It says
they are ID 25/64” and OD 5/8”. These washers are about 1/16” thick and will seal just fine -- but will aggravate
another problem.

Craig Sawyers pointed out that the alignment of the cross hole in the banjo bolt doesn’t line up with the channel inside
the collar as well as might be hoped -- see Figure 1. The collar is about 13/32” thick, with the channel right in the
middle, but the cross hole in the bolt is located only about 5/32” from the underside of the head -- and the thickness of
the sealing washer between the bolt head and the collar makes this misalignment even worse. The drawing at left
includes a 1/16” thick copper washer, and the two passages barely overlap. Jaguar’s fix: those really thin sealing
washers described above.

A better fix is pretty easy, though: using a Dremel or some such, lengthen the opening on the cross hole in the bolt in
the direction of the threaded end (basically, enlarge the chamfering in that direction). This will help the oil flow to the
camshafts even if the original thickness washers are used. Ideally you will want to extend the edge of the cross hole to
about 5/16” or 8mm from the underside of the bolt head.

Figure 1 - Banjo Bolt Modification for Better Oil Flow

Craig Sawyers came up with a slightly different mod: “I added a single extra 2.5mm diameter hole (ie not all the way
through, just until it entered the axial drilling) with a centre line 6.7mm from the sealing face. that puts it entirely in the
channel in the oil feed line.”

Now that you’re practiced at this modification, do the same thing to the banjo bolt at the top right of the radiator -- see
page 187.

If you’d prefer, Ron Kelnhofer (page 716) offers a custom banjo bolt to replace the OEM item. He includes a pair of
copper sealing washers with each bolt that are 0.031” thick -- thicker than the OEM washers and thick enough to seal
properly, but only half as thick as the Help! items described above. Kelnhofer located the cross hole in his banjo bolt
correctly for his 0.031” sealing washers; if either the thin OEM washers or the thicker Help! washers were used with it
the cross hole would still line up better than the OEM banjo bolt with the OEM thin washers, but nevertheless
Kelnhofer suggests you use the washers he designed it for to ensure optimum flow.

He also made his banjo bolt a little longer. “1.015'' long overall. The bolt was lengthened only an amount equal to the
change in the washer thicknesses.” It is therefore not a solution for the stripped banjo bolt hole problem described
below. “The reason behind this is that with the limited amount of space between the head and the firewall, I wanted to
keep it as short as possible but still permanently address the real issue, leaking. I could have made them longer but
actually can't see a real benefit as far as sealing is concerned by doing so. As far as stripping the head threads, my
feeling is that it isn't really a problem if one uses common sense in tightening the bolt.”

Kelnhofer’s banjo bolt is made of stainless steel. You can look at a pic of this bolt at

http://neptune.spacebears.com/cars/engr/banjoeng.html

When tightening banjo bolts, be sure to hold the collar on the oil line still. Failure to do so will allow the turning of the
bolt to twist the collar and bend the tubing.

STRIPPED BANJO BOLT HOLES: The banjo bolts thread into the back ends of the tappet blocks only about 0.35”.
That’s not much thread engagement for screwing 3/8” bolts into soft aluminum, and combined with the fact that the
banjo fittings often leak at assembly due to the thin copper washers, it’s only too common that a mechanic tightens
them too many grunts trying to stem a leak and winds up stripping out the threads in the tappet block. This will require
many pints to get over since it would normally require removing the tappet block to helicoil, and removing the tappet
block requires removing the camshaft, and removing the camshaft requires fiddling with the timing chain tensioner --
see page 64.

Modifying the banjo bolt and using thicker copper washers, as described above, will solve the sealing problems and
make it unnecessary to go cranking on that banjo bolt so hard -- but it also means that there are even less threads
engaged, so being judicious about tightening is highly recommended.

Nick Johanssen and Craig Sawyers report that the Jaguar Enthusiasts’ Club (page 727) offers longer banjo bolts. “A
get-you-out-of-trouble idea for a temporary way of avoiding the removal of the cylinder head if the original bolt's
thread strips. This bolt has extra threads to take up with the deeper threads always present, but not always made use
of.” He means avoiding removing the tappet block rather than the cylinder head of course, but it’s still a task to avoid.

Of course, it might not be a bad idea to install the longer banjo bolts before the threads strip.

Note: the JEC banjo bolts are nice and long, but the cross hole is still in the wrong place. Before installing, you will
need to modify them per the guidelines above.

There are also questions about the quality of these parts. Sawyers says, “the thread had been made with a worn die. It
was as rough as a badger's backside, and was too large (like a nut wouldn't go on with just fingers). So I had to run a
3/8 UNC die down it - curling out a spiral of extra metal in the process.” Considering the soft aluminum tappet blocks
these things screw into, finding such a die and chasing those threads is certainly prudent.

Classic Jaguar of Austin, Texas also offers longer banjo bolts, part number C5846L (the L is for Long). They’re
supposedly about 3/16” longer than the OEM banjo bolts. No word on whether the cross hole is correctly located or
whether the quality is any better than the JEC items. They might actually be the JEC parts, just kept in stock on this
side of the pond.

Some people have suggested simply making new banjo bolts from normal bolts; just drill one hole axially down the
length of the bolt and another crossways. Sawyers: “The head of a standard 3/8 UNC bolt is 9/16AF. The banjos are
5/8AF - the increase in AF size for the head gives a larger land for the copper washer to seat.” IOW, it might work, but
you’ll have less sealing surface under the head. Perhaps better to just buy the correct items -- unless you can find 3/8”
UNC bolts with oversize heads.

Note that there is at least one report of longer banjo bolts being too long and bottoming in the threads before tightening
down on the sealing washers, thereby causing a massive leak. It’s all a function of how deep the hole was threaded.
Hence, if installing a longer banjo bolt, it is recommended that it be trial installed without sealing washers first to make
sure it’ll screw in far enough. If they bottom too soon, the solution is obvious: shorten them a bit. Meanwhile, if you
ever have the tappet blocks off, check the threads and if they’re not tapped plenty deep, go ahead and tap them deeper
while you can.

Things are tight back there, and problems may arise trying to get the longer banjo bolts in place with the engine in the
car. Trying to get them in between the firewall and the fitting on the oil line is probably not going to work. Rather,
gently bend the oil line upward until it clears the back end of the tappet block, insert the long banjo bolt with one
sealing washer around it, then gently bend it back to the proper position. Use a length of dental floss to hold the second
sealing washer in place, get the banjo bolt started, then cut the dental floss and pull it out.

This will work, but obviously you don’t want to do it a dozen times; eventually the tube will crack and you will need a
new one. To ease the stress on the tube, you could unscrew the banjo bolt from the oil pressure sender pedestal or
unbolt the pedestal itself, which will allow moving the oil feed manifold around much more easily. This will allow
moving the ends out from behind the tappet blocks more easily -- and if you’re coordinated, you might consider putting
the banjo bolts into the fittings for both tappet blocks at the same time rather than bolting one down and then bending
the tube to install the second. Alternatively, you might do the right bank first -- it’s the hard one -- and then you may be
able to get the left one together without even having to move the oil line around.

LEAKY OIL PRESSURE SENDER CONNECTIONS: The connection at the block at the rear center of the V is a
larger banjo bolt. For this fitting, Help! number 66265, “Brake Hose Bolt Washers” are a perfect fit. They are
described on the package as ID = 33/64”, OD = 45/64”. These same seals fit the bolts that hold the heat shields to the
exhaust manifolds -- see page 316.

The seal on the oil pressure sending unit itself is not the same size as on the banjo fitting. The sending unit fitting is the
same diameter as many common oil drain plugs, though, so it is easy to find a suitable seal in an auto parts store. Note,
however, that if you’re buying a new sending unit, it will usually come with a new sealing washer.

LEAKY OIL PRESSURE SENDER: When searching for sources of oil leaks, don’t overlook the oil pressure sending
unit itself, C46272. The unit can fail internally and oil comes seeping out of the electrical connector, a sure sign of
trouble since there isn’t supposed to be any oil within the electrical components in this unit. The author’s car had this
problem, and the gauge was still working just fine. The only solution is to replace it. A sender with silicone sealant
around the connector is a sure sign that an incompetent mechanic has been involved.

For more on this sender, see page 55.

LEAKY OIL PRESSURE SWITCH: The oil pressure switch, which operates the warning light, is right next to the oil
pressure sender -- and is even more notorious for leaking oil out through the electrical connection. The only solution is
to replace it, but that’s not difficult because the thread is standard and there are lots of cars that use very similar pressure
switches. David Johnson says, “I screwed one from a Chevy in. The new one was a two wire type, so I simply
connected one side to ground and it works fine.”

OIL LEAKS AT FILTER HEAD ASSEMBLY: Peter Smith says “The oil would gather around the top of the filter
less than a minute after starting the engine. I eventually took the head assembly off and found a blanking bolt fitted to
the rear which had a failed fibre sealing washer. Replaced it with a copper washer - no more leaks. I had to take the
head assembly off to see the bolt but when you know it’s there it may be possible by feel.”

OIL LEAKS AT CAM COVER/HALF MOON SEAL: Discussed on page 59.

OIL LEAKS AT TAPPET BLOCK: Discussed on page 70.

OIL LEAKS AT TIMING CHAIN TENSIONER ACCESS COVER: Before going any farther, please read the
warning about having the cam covers off on page 59; the same warning about dropping parts inside applies here.

The access to the timing chain tensioner latch is via an opening on the timing chain cover, forward of the right bank and
just above the support for the belt-driven fan. The purpose of this access is for locking or releasing the tensioner during
overhauls; there is no need for periodic adjustment, as the tensioner is self-adjusting.

The rubber plug always seems to get hard and crumbly. People with the new one in hand sometimes assume there has
been a material change, since the new one is soft and pliable while the old one appears to be Bakelite. Looking at the
ears on the new one can also lead one to believe that it’s a push-and-turn type of cover, like a radiator cap. No such
luck; it’s a simple round hole, and the ears are supposed to be flexed to get it in and out. The old one will probably
have to be removed in pieces. If a piece or two falls down inside, don’t worry about it, they’re too soft to do any
serious damage. They’ll probably just come out in the next oil change; it’s definitely not worth further disassembly.

Mark Jackson says, “Managed to get the hardened rubber bung out the hard way with wood screws and a home made
tool made out of 1/8" round which I levered with a screw driver via a nut on the chain cover!”

Note that this is an opening into the crankcase and should be well sealed to prevent oil vapor leakage, as well as to keep
the PCV system working properly to minimize oil leaks elsewhere. Chad Bolles suggests “...apply a thin coat of GM
Gasket Sealing Compound part no. 1050026 (stuff never gets hard) and press in the new plug and you are good to go.”

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