[xj-s] water rail question

Mission creep has really set in. I am now considering
Lutzing my water manifold, and replacing the water rail. I
have researched the archives about using stainless, and it
seems that some fear galvanic corrosion between the
stainless tube and aluminum housing. Others are of the
opinion that the rubber seal will insulate the two. Some
prefer copper.

At this point, I have two options in hand- precut and ready
to go. 304 Stainless, which is a slightly thicker wall, and
consequently, a slightly smaller flow diameter. I also found
aluminum tubing that is the same wall thickness as the
original steel tube. It polished up fairly well, and almost
looks like stainless.

Questions:
Would the thicker wall stainless effect the flow through the
rail enough to worry about? Will the difference in
expansion/contraction of the dissimilar metals effect the
sealing integrity?

Why are so many people using copper instead of aluminum
tubing? Pressure rating? Appearance? Fragility?

The Stage 1 Lutz mod seems alarmingly small in the first
port. 1/8 inch looks pretty small. I am sure any size
restrictor will promote flow to the rear manifold. Would
3/16 or 1/4 be an option? What have others fond to be optimal?

The Lutz press-fit concerns me a bit, too. However, I don’t
like the gasket sandwich restrictor idea because I think it
would make the front manifold gasket too thick, resulting in
the front rail being higher than the rear, which may effect
the alignment of the water rail, compromising the rail seal.

I would love to read others opinions, and experiences.–
1990 XJ-S V12 5.3 Coupe
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In reply to a message from Billbo sent Sun 20 Nov 2011:

Bill-
My water rails are stainless, I don’t remember the alloy but the
walls are thicker than the stock tubes. I got the tubing from
McMaster-Carr, it was pretty cheap. I did a satin finish on the
outside with 800 grit paper on a lathe.
Had one off recently when installing new temp gauges, no signs of
corrosion after 5 years.
I do not have the Lutz mod. I have mechanical gauges with senders
on the left front corner and right rear corner water manifolds.
The temperatures track each other almost exaclty, maybe +/- 1-2
degrees worst case.

Pic: http://www.goflyrc.com/projects/XJS/P9120014.JPG
That’s my experience.
Bob–
The original message included these comments:

Mission creep has really set in. I am now considering
Lutzing my water manifold, and replacing the water rail. I
have researched the archives about using stainless, and it
seems that some fear galvanic corrosion between the
stainless tube and aluminum housing. Others are of the
opinion that the rubber seal will insulate the two. Some
prefer copper.
I would love to read others opinions, and experiences.


89 XJS Coupe, Mesa AZ GoFlyRC.com - 1989 Jaguar XJS Coupe
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I do try to keep up but I’ve never heard what the “Lutz Mod” really is. Can
you explain? Is it in Kirby’s book, by chance?

Cheers
Doug Dwyer
Longview Washington USA
1995 XJR

I do not have the Lutz mod.

// please trim quoted text to context onlyFrom: “BobPhx” brackney67@gmail.com

Would the thicker wall stainless effect the flow through the
rail enough to worry about?

In my opinion, no. I had a 1/2" stainless steel flat washer
installed in my RH upper radiator hose to encourage more flow through
the B bank, worked fine. Lutz disagrees, though, and advocates going
with a LARGER pipe than OEM to maximize flow.

Will the difference in
expansion/contraction of the dissimilar metals effect the
sealing integrity?

If you’re talking about installing the SS pipe in the same manner as
the original, using the top hat seals, no. Those seals work very
well, at least until they dry out and crumble. The biggest threat to
them sealing is using a steel tube that rusts, since the rust will
break the seal. Thank you Jaguar for providing the worst possible
material in this application.

Why are so many people using copper instead of aluminum
tubing? Pressure rating? Appearance? Fragility?

The copper is handy because it’s readily available in the correct
size, no machining necessary. Just use a tubing cutter to cut a
piece to length. If you wanna do a top-notch job, cut rings off a
sweat fitting and solder them in place around the copper tubing to
prevent it from sliding too far into the rubber seal.

I also thought it looked kinda neat, but aluminum would look nice,
too. The only thing that doesn’t look good in that application is
rusty steel. Thanks again to Jaguar…

The Stage 1 Lutz mod seems alarmingly small in the first
port. 1/8 inch looks pretty small. I am sure any size
restrictor will promote flow to the rear manifold. Would
3/16 or 1/4 be an option? What have others fond to be optimal?

IMHO, the Lutz mod renders the first port pretty much a bleed port,
something to let air bubbles out of that corner when filling. The
flow through that port might be enough to prevent the coolant from
stagnating, but it’s likely not enough to keep the front cylinders
cool. The idea is clearly to drive essentially all of the flow past
all of the cylinders.

Going with a larger port might work for the same reasons that not
doing the Lutz mod at all might work. The thing is, though, that I
personally suspect that the OEM setup was thoroughly tested at Jaguar
and found to work fine at full power, but we owners discovered that
it doesn’t work well at idle where flow is weak enough that all of it
can pass through that first port and none gets to the rear of the
engine. If that’s the case, then the Lutz mod to the first port
would need to be pretty small indeed, because your objective is to
restrict flow here at idle where flow is weak all around.

Those who have performed the Lutz mod as specified haven’t reported
any downsides that I am aware of. Of course, most of them probably
wouldn’t know if their 1A and 1B cylinders were running hotter than
the rest. There are a few members here, though, who have purchased
IR thermometers, though, and use them to look for hot spots, and I
don’t think they’ve discovered anything alarming resulting from the
Lutz mod.

The Lutz press-fit concerns me a bit, too. However, I don’t
like the gasket sandwich restrictor idea because I think it
would make the front manifold gasket too thick, resulting in
the front rail being higher than the rear, which may effect
the alignment of the water rail, compromising the rail seal.

Nonono – the way I would do the gasket sandwich idea would be to
do it at all ports, front and rear. The restrictors at the back
just aren’t restrictive, they’re full size passages.

– Kirbert

// please trim quoted text to context onlyOn 20 Nov 2011 at 8:07, Billbo wrote:

I do try to keep up but I’ve never heard what the “Lutz Mod” really
is. Can you explain? Is it in Kirby’s book, by chance?

Not yet! Haven’t updated the Book since Norman showed up and
described his mod! Basically, it’s plugging up the forward two
coolant outlets on each head so virtually all the coolant must go the
length of the head and come out the rear outlets. Only tiny openings
are left at the front.

There’s also a Stage II which goes farther including replacing the
coolant pipe between front and rear manifolds with a larger diameter
pipe for more flow out of the rear.

– Kirbert

// please trim quoted text to context onlyOn 20 Nov 2011 at 10:25, Doug Dwyer wrote:

In reply to a message from Doug Dwyer sent Sun 20 Nov 2011:

I will try to explain, as I understand it. The four ports in
each bank of the cooling manifold are a tad bit less than
.75 inches in diameter each. The tendency is for the water
pump to ‘‘short circuit’’ the flow, causing the majority of
the flow to go through the front manifold housing, creating
less flow through the rear ports. By restricting the flow in
the front two ports (for normal road use), more flow is
achieved around the rear of the heads. Norman Lutz is the
man with the idea. Stage 1 mod has the first port restricted
to 1/8’‘, #2 restricted to 1/2’', and the last two ports left
open. So… by gradually stepping up the orifice size, the
flow is more balanced. Interesting theory, and he produced
some math to back it up.

Bob- Thanks for the follow-up report on the stainless. I am
fortunate to work in hydraulics, and have a great supply of
tubing at my disposal. I still don’t fully understand how
that rail seal actually holds any pressure without weeping.
But your 5 year follow-up seems to back up the idea that the
seal acts as an insulator to prevent galvanic corrosion
between the aluminum and stainless. I think as long as the
coolant is kept fresh, there should not be a problem.–
The original message included these comments:

I do try to keep up but I’ve never heard what the ‘‘Lutz Mod’’ really is. Can
you explain? Is it in Kirby’s book, by chance?


1990 XJ-S V12 5.3 Coupe
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Kirby and Bill, thanks for the explanation

Cheers
Doug Dwyer
Longview Washington USA
1995 XJR

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In reply to a message from Doug Dwyer sent Sun 20 Nov 2011:

I used ally tube and think it was 28mm and I made a jig by
measuring the holes on the head and then mounted a new length of
the cut length between the water rail ends. I screwed the ends to
the wood and got a friend with many years TIG welding to TIG weld
the ends to the new tube as it was ally to ally . You need to be
good at TIG as the tube wall was thin and east to burn a hole. I
then unscrewed the new rail and bolted them back on the car after
the reducers were fitted in place. I have some pics and when I find
them I will post a link. No rubber seals are required as the
welding is perfect and strong. My old rails were starting to rust
on the outside but not on the inside of the old steel tube.–
95 XJR6, 94 XJS 6.0 coupe, 04 XK8 ,99 Ka
Croydon , SURREY, United Kingdom
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In reply to a message from 540itouring sent Sun 20 Nov 2011:

This is a link to my pics of the water rail

http://tinyurl.com/88nf64x--
The original message included these comments:

I used ally tube and think it was 28mm and I made a jig by


95 XJR6, 94 XJS 6.0 coupe, 04 XK8 ,99 Ka
Croydon , SURREY, United Kingdom
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In reply to a message from 540itouring sent Sun 20 Nov 2011:

Great photos- thanks. I wish I could weld like that. I think
I have decided to skip the mod and try the stainless. I have
not had any cooling issues yet, so why add another variable.–
The original message included these comments:

This is a link to my pics of the water rail


1990 XJ-S V12 5.3 Coupe
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In reply to a message from 540itouring sent Sun 20 Nov 2011:

Dave your welder gets an ‘‘Oscar’’ for the year for beautiful
welding. What a great job! I found 3/4’’ alloy tubing suitable for
the job at Home Depot and used the rubber hat seals. No leaks and
no muss,no fuss. The next stage would probably be to Stage III as
you could most likely install Silicon hoses from the outside of the
alloy casting to the rear with stainless hose clamps. Perhaps Norm
Lutz will comment as he did the math on this entire modification.
Best, JW… Aircraft Mechanic Handbook ASA-MHB-5 still
says stainless and aluminium are not the best togather. Best, JW–
The original message included these comments:

This is a link to my pics of the water rail

I used ally tube and think it was 28mm and I made a jig by


86XJ-S cpes,Ballet I,Act II,Lutz stg.1,288 Dana
Fresno, CA, United States
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In reply to a message from Dr.Quail sent Sun 20 Nov 2011:

Norman asked me to post some pictures some time ago.
http://www.jag-lovers.org/snaps/snap_view.php3?id=1287747811

You may also want to consider whether your thermostats/bypass ports
work properly. Search my posts around the time this photo album was
posted.
http://www.jag-lovers.org/snaps/snap_view.php3?id=1295366040

kind regards
Marek–
MarekH
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In reply to a message from MarekH sent Mon 21 Nov 2011:

Marek, where did you find the Delrin inserts for the thermostats as
this has always been a critical issue with Grant Francis back
several years.? Norm Lutz really has covered the bases on this
issue. Best, JW–
The original message included these comments:

Norman asked me to post some pictures some time ago.
You may also want to consider whether your thermostats/bypass ports
work properly. Search my posts around the time this photo album was
Marek


86XJ-S cpes,Ballet I,Act II,Lutz stg.1,288 Dana
Fresno, CA, United States
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In reply to a message from Dr.Quail sent Mon 21 Nov 2011:

Dear JW,
I made the Delrin inserts myself. It’s a critical issue for
everyone else aswell.
For more details, search the archives for ‘‘thermostat’’, cross
indexed against ‘‘MarekH’’.

kind regards
Marek–
MarekH
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In reply to a message from MarekH sent Tue 22 Nov 2011:

Beautiful job, I wonder if they could be turned on a Drill
Press??? I don’t own a lathe so would have to job them out, would
run a bunch if cost effective, make them available to the list at a
reasonable price. How about the Lutz inserts…would delrin
work or fail to hold as a forced fit like the alloy inserts I made
up from alloy stock? Best, JW–
The original message included these comments:

I made the Delrin inserts myself. It’s a critical issue for
everyone else aswell.
indexed against ‘‘MarekH’’.
Marek


86XJ-S cpes,Ballet I,Act II,Lutz stg.1,288 Dana
Fresno, CA, United States
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In reply to a message from Billbo sent Sun 20 Nov 2011:

As well a Jaguars, I also have a couple of BMW’s.
My 540 Motor Sport 4.4L V8 has no water outlets at the front of the
heads, all the water goes in the front of the block and exits out
the rear of the heads to a water rail that feeds a return pipe that
is located in the centre of the valley.
This engine makes more HP than my XJS which means more BTU’s into
the cooling system than the XJS.
It also has a smaller radiator, but it never gets as hot as my XJS
used to prior to my mods.
Why would a press fit worry you? It is used in many appilications
in automobiles were high mechanical loads are present.
The cooling sytem has virtually no mechanical load other than the
resistance to flow of water, so the restrictors will never be
dislodged.–
The original message included these comments:

The Stage 1 Lutz mod seems alarmingly small in the first
port. 1/8 inch looks pretty small. I am sure any size
The Lutz press-fit concerns me a bit, too. However, I don’t


850225/679,1E21003,2W2001BW,JNAEY3AC100218,SAJNV4841KC156072
HEIDELBERG HEIGHTS, Australia
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In reply to a message from Kirbert sent Sun 20 Nov 2011:

Installing a 1/2 washer in the RH top raditor hose negates the
variable control that is provide by the thermostat and is totally
unneccessary.
The reason Jaguar went to twin thermostats was to get more precise
flow control to each bank. I have never seen any other V engine
that has this feature.
The pipe I say needs increasing in size is the one between the
front and rear water manifolds so as to provide adequate water flow
at high speed.
V12 Carby engines had a larger pipe than the FI engines.
Also the V12 E ran the water pump at a much lower speed than the
saloons as it was expected that they would spend more of their life
at autobahn speeds.
The restrictors in the front manifolds are required for control of
water flow at idle or low speed such as in heavy traffic conditions
in hot weather with the AC on.–
The original message included these comments:

In my opinion, no. I had a 1/2’’ stainless steel flat washer
installed in my RH upper radiator hose to encourage more flow through
the B bank, worked fine. Lutz disagrees, though, and advocates going
with a LARGER pipe than OEM to maximize flow.


850225/679,1E21003,2W2001BW,JNAEY3AC100218,SAJNV4841KC156072
HEIDELBERG HEIGHTS, Australia
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