Yes, Doug, it looks like 4 so far. So this has possible implications for the air purge system.

I actually asked Mark to perform the tests, so as to have a greater sample than 2.

There is (at least that I can find) no official Jaguar info on the design intent of the air purge system, other than the flow schematic in the service manual. However, it does not show the intended flow direction in the bleed pipe from the filler neck to the the banjo bolt. This is the only line, in the schematic, that does NOT show a flow direction....interesting in itself, as if no one at Jaguar knew,or could comprehend, the direction of flow.

Having now, thoroughly, thought about the whole system, for quite a while, logic dictates, as per Palm, that the flow proceed from the filler neck to the banjo bolt, to have any hope of the system performing as intended.

So what if this valve is left out of the system?
I think, that the air purge system will work, mostly, as intended if there is perfect, unobstructed, flow through the radiator, with thermostats fully open.
It should work, efficiently, as intended, (sucking flow from the top of the radiator and the "closed" circulation within the engine), while the thermostats are closed, during warm up....no back pressure from the right top hose at this stage. A little, careful, thought will reveal that, once warmed up t'stats fully open, the system will tend to become hopelessly inefficient as radiator plugging/clogging progresses......the left hand side ejector set up, will begin to be overwhelmed.

So what if the EAC4126 valve is installed the "wrong" way (as per the four cases thus far),so flow is "allowed" into the filler neck from the banjo bolt?
With the thermostats closed, air will be purged from the top of the radiator only and not from the "closed" circulation within the engine. I think, that the air purge system will work, mostly, as intended if there is perfect, unobstructed, flow through the radiator, with thermostats fully open,but be "blocked" from purging flow/air from the filler neck. As with no valve (above paragraph) the system will tend to become hopelessly inefficient as radiator plugging/clogging progresses......the left hand side ejector set up, will again begin to be overwhelmed.

So what if the EAC4126 valve is installed the "right" way? At warm up, with thermostats closed, and perfect radiator flow, the system will purge from both
the radiator top and filler neck as intended. Again, with perfect radiator flow, with the thermostats fully open the system will continue to function as intended. However, and I think this is the real intent of this valve, as radiator flow diminishes, over time, the increasing back pressure from the top hose will not be allowed to flow (and "expand" thus creating even more flow in this direction to overwhelm the ejector set up) into the filler neck. Indeed, as radiator flow/efficiency deteriorates, air purge from the top of the radiator will be enhanced by the top hose back pressure being directed into the header tank (which some, including Jaguar EPC, will know as the expansion tank) as is the design intent.

With the the valve in the "wrong" way and a deteriorating radiator flow, the woes of a, poorly maintained, cooling system will only increase over time,due to trapped air in the system.Thus, as per palm, a correctly functioning air purge is one of the prerequisites for maintaining cooling efficiency.

Bottom line here, I think, is the connection from filler neck to the banjo bolt, introduced with the HE was to enhance the air purge effect of the jiggle pins in the thermostats during warm up when the t'stats are closed....may even be a fail safe for t'stats installed with jiggle pins not at the 12 o'clock position or even t'stats without jiggle pins. The valve was then introduced to stop a deteriorating radiator, back pressure flow, from disabling the ejector set up, as per previous above reasoning. I'm assuming that at full cool down of the engine, as the pressure of to system falls to ambient atmospheric pressure, that air will come out of solution and accumulate in the engine block/heads.

It occurs to me, that the pre HE may be less prone to overheating due to poor coolant maintenance than the post HEs, as they will not be relying on a correctly installed (nonexistent) water valve, to air purge the system. Can't remember any overheating problems with my Boss's V12 E type back in the early '70s and we blasted that thing all over Europe ( ah! the good old days, flat out on the autroutes...well at least for a few miles or so).... and I did the routine maintenance on it.

Now, I may be WRONG (nothing is 100% certain in life, except death) in my above assessment of the three possibilities but, as Greg said in the previous post, I can come up with no logical explanation for why Jaguar (at initial factory assembly it seems) would choose to install the valve the "wrong" way,
as per the four cases we have found so far.

Now I come to think about it, my explanation of the correct "right" way installation, brings to mind......resistance, voltage, diodes, back emf etc. both are flow systems, with directed flow intent.

Please, someone prove my above assessment, of the situation, is erroneous.
This is driving me nuts.

I have not thought about how, a blocked atmospheric tank, might further effect the system, as mine is working as per Palm's description/tests.

There are,also, other small flow considerations (with t'stats closed/open), as far as creating a changing "push you pull me" situation, as the cooling efficiency deteriorates.

Anyone?

Thanks for listening, I had to reread this several times to get this straight in my mind, and I wrote it!

Rob.
2006 X Type Wagon.
1994 XJS 6.0 V12 convertible.
1987 XJ6 DD.

 

"Nothing is certain except death and taxes" Dr Johnson's most famous words!
As to the valve, you have lost me a bit now, to summarise, are you thinking on balance that Palm is correct?
I still cannot see why there would be a pipe connection to the radtop bleed system at all if the valve was intended to prevent air getting to it from the cross pipe spout.
Finally The Wizard of Oz always left it out anyway, and his car went all round the edge of your island no problems. So in the absence of any better explanation I come down on NO valve, or valve allowing air out of the spout.
But I await the results of Doug's thinking with interest.
Greg

 

Thanks for the quick response Greg.

I wrote that post to try get it all straight in my head......I have always designed, my products, in my head first, then to manufacture.

I know what I wrote was a bit pedantic.....but I like fine details..."the Devil may well be in the details).

Read the post several times....I did it under the hood, imagining myself flowing around the system, with the various options in play.

Yes,99.999999999% (shades of the infinite improbability drive here!) certain Palm is right.

Yes, 99.999999999999999999999% certain, no valve is preferable to one in the wrong way....cooling must be close to 100% though.

99.999999999999999999999999999999999999% certain that, some, Jaguar engineers did not have a clue as to the design intent of, some, of their predecessors. Remember, English car/motorcycle designers/engineers in the 50/60s where mostly "seat of the pants" types....Edward turner et al.

Thanks,

Rob.

 

I have an engine from an "84 Coupe. The water valve on it is oriented in the same direction as my '88 and '89.








Mark

 

I've now received a bunch of the EAC4126 Water Valves.

The valves themselves (see photo) are very well machined from 303 non magnetic stainless steel rod. The surface finish is very fine on the OD.

The aperture ,where the jiggle ball locates, has a very small .003" 45 degree chamfer, to break the sharp edge of this aperture and provide a good seal....not an easy thing to do as the unit was made in just one machining operation. This is a very well made part.

The step in the, open, end of the OD is very consistent (in the six samples I have) with an OD and roundness of plus or minus .0002", at a mean diameter of .3675". The remainder of the OD (intended as a "lead in") is the same tolerance at .3585" mean OD.

The "plastic" jiggle ***** have a mean diameter of .239".

I managed to remove the one from my bypass filler pipe spigot, as with Mark's photos, the open end was flush with the end of the spigot. The old unit (a bit mangled from removal) was the same form and function as the new units.

This valve casing was obviously designed to be inserted in the larger open end of the spigot which after, just over,1/2 inch reduces down in diameter.

So, as previously discussed, the five samples so far examined, would not allow flow from the filler pipe to the banjo bolt, and therefore the system could not perform as per Palm's (and other's) descriptions.

The hose from the banjo pipe (1/4" ID) to the filler pipe spigot (3/8" ID) has only about 2.1" of 3/8" ID at the spigot end.....so I do not think the valve was intended to be fitted in the hose itself.

So, wishing to get the system functioning as per Palm's description, I fitted a new valve as shown in the photo...I did not try to press it in any further than shown.....admittedly this does look somewhat incongruous. I did not push the hose right up to the filler neck itself, I left it about 3/16" short of being butted up against the filler neck, to ensure that the jiggle ball would not be confined by the 1/4" ID part of the tube.

So now a test, with the jiggle ball towards the banjo bolt. Starting the engine from cold,I felt the metal pipe from the spigot hose to the banjo bolt, it got warmer than ambient (80F) in about 20 seconds and really warm at about 90 seconds. This, I believe, shows flow from the filler neck to the banjo bolt. I think my thermostats start to open at about 4 mins or so. I shut the engine off at just over the 90 second mark.

I left the engine to cool down for about 2 hours.

Then I removed the filler pipe cap and the coolant level was right to the top....I don't recall it being anything other than at the bottom of the filler pipe on previous examinations. This indicates that with the thermostats closed, flow was certainly flowing to the banjo bolt.

Next test, fitted the jiggle ball towards the filler neck, as per the five examples found so far in this post, after 2 mins of running the engine (from cold) there was no detectable warming of the pipe to the banjo bolt. Thus there was no flow from the filler pipe to the banjo bolt. At 4/5 mins it started to get warm as the top right, radiator, inlet, hose was getting really warm at this point....convection/heat conduction from the radiator at this point.

Well, still, I'm thinking that this set up was added with the HE to thoroughly purge air from the engine block before the t'stats were fully open. Hence the jiggle ball must be towards the banjo bolt or the other part of the air purge system will maybe not perform as intended, if the cooling system is not 100%.

If anyone has a 1981 V12, perhaps they could perform the flow test, as per the previous posts.......this will show if the valve had been inserted the, presumed, "wrong" way, consistently, from the very first production units.

Tomorrow I will try and get some idea of how much suction the system has to purge the air through the header tank.

I'm, really,beginning to think that the jiggle ball was originally designed to be INSIDE the the valve body...the ID here is .315"....this would then fit neatly in to the filler neck spigot, with the jiggle ball facing the banjo bolt. This could make a difficult,production, assembly job....I believe the tiny, stamped, brass anchor maybe a press fit in to the jiggle ball...or maybe molded around the anchor. I will try and modify one of the valves to this configuration tomorrow...will definitely be a neater fit in filler spigot.

Thanks for "listening",

Rob.
2006 X Type Wagon.
1994 XJS 6.0 V12 Convertible,
1987 XJ6 DD.

 

For what its worth, l have a cathouse spares stainless crossover pipe fitted which does not and never has had a valve fitted (not sure if all cathouse were the same) with no problems in the cooling system efficiency.

 

Thanks for the info Baxtor.

I've actually contacted Cathouse spares a few times, for a stainless bypass pipe but had no replies to date.....all I've been able to track down is a pre HE pipe available in OZ, in stainless.

I'm doing a complete renew of the cooling on my 6.0 V12 this winter,including all stainless steel pipes and header tank and filters, so was quite bemused by the function of of the water valve in my system, given the emphasis that Palm puts on its correct operation, for the air purge to work correctly.

Also, I'm assuming that the 6.0 has at least 13% more "waste" heat to deal with than the 5.3.....so I'm wanting to get the cooling 100% for next summer.

Yes, I believe that with a 100% free flowing radiator then no valve, is way better than a valve working the "wrong" way as in the five examples, we have found, so far.

Still waiting for Doug to chime in.

Rob.

 

Rob
My experience is exactly as you describe so clearly. With the flow possible to the banjo, no air in the cross pipe filler tube. Other way round, always air there.
Thanks for such a brilliantly clear post and what a great idea about how to test the system.
Greg

 

I sent an email over to Kirby Palm and asked for his thoughts regarding this subject. He read the thread and sent me the following response;

"I agree with virtually everything that's been said! The water valve on my '83 was built into the filler neck and it was oriented so that flow would go INTO the filler neck but not the other way around. And I am convinced that is WRONG. Probably a screwup at Jaguar that nobody ever noticed or corrected. I simply cannot see how the air extraction system can work properly unless you either reverse that valve or remove it entirely.

-- Kirbert"

I think I will order some new water valves and install it the way Kirby recommends. I will report if I notice a difference in operation or its affect on cooling performance.

Mark

 

I have nothing to add ! Your rationale works well for me at this point



Cheers
DD

 

Thanks Doug....I was beginning to think I was going (more?) senile.....65 in a few weeks.

Rob

 

Hi all,
I am currently replacing the 20 or so hose pieces in the cooling system after one of the hoses swelled and got a leak, do one, do them all. System is only as good as its weakest hose. I remembered this thread and wanted to come in my experience.

As i see it, my system, 95, had the ball toward the filter neck. I know that in normal operation, the filter neck had no air in it so the purge did work.

My belief is that this is designed to primarily allow a flow of air only, but that a denser fluid would be precluded to flow toward the filterneck. The filter neck, and radiator banjo bolt are joined together with a small diameter metal tube and this goes to the venturi pipe on the LHS created by the two different size metal pipes, so that as coolant is forced through the smaller pipe, when it expands to the larger pipe, a lower pressure is created that sucks any air. The valve is to stop any undesired fluid flow back into the neck, if the cap were removed.

I think under normal operations, the should be no coolant flow from the filter neck to the banjo bolt.

I believe correct valve orientation is the ball to filler neck, as experienced in the samples tested.
Correct air purge depends on correct operation of the venturi effect created by the mixed pipe diameters.
My thoughts on the matter.
Dave

 

Dave
I think we all agree about the jet/extractor venturi effect of the twin diameter Y pipe purge system. If your experience is that the non-return valve orientated in "does not allow coolant to flow to the banjo" position does allow the centre fill pipe to remain air-free then that is exactly as we all agree it should be. My problem, and Rob's I believe, was that when the valve was orientated in this way on our cars, the fill pipe did not purge itself from air; but when we fitted the valve the other way (allow water to flow towards the banjo) the fill pipe did purge itself of air.


Assuming you are describing what your system is actually doing, rather than in fact the valve for whatever reason is actually letting water through to the banjo as well as air, then the only feed for the jet extractor system must be up through the banjo, up into the thin radtop pipe, and out through the extractor. This ensures the rad itself is purged of air, and is part of the reason for the system. My only question for you is, does the rubber pipe from the fill pipe to the banjo get hot? If it does, there is water going through it, if not and it is just warmish, there is not. This was the test Rob described.


Either way, as long as the fill pipe remains airfree, we are all happy! Good luck with all the small pipes.
Greg

 

Hi Greg, thanks, certainly, my fill tube would purge all air with the valve set to stop large flow out, with the ball oriented toward the fill.

Will be cleaning the fitting ends and the cross tube today. There are lots of connections aren't there, and so many sizes...

What clamps do you recommend? Original NORMA/jubiliee style or a change to constant tension spring clamps?

 

On most of the hoses I use Jubilee type clips and have never had a problem; except for the hose clamp on the big hose to the water pump inlet from the bottom of the rad. The pump inlet spout is ally and over time it corrodes a bit on the casting under the hose and clamp, and can weep annoyingly. For this I use a Mikelor-type high pressure hose clip (eg HOSE CLAMPS). These are also known as T bolt clips and are available from all sorts of suppliers, Ebay etc etc. Complete sod to get at, naturally !


Greg

 

Perhaps this cooling system diagram is the one you remember

 

Error double post

 

I certainly had not seem this. Must be of an early technical write up, when folk had time to do it. The one part missing is the venturi air purge lines, that has the high pressure line from the LHS thermostat through to the low pressure side pump inlet via a dedicated 3/8" inlet hose through the cross tube to the pump inlet.

Certainly is an interesting case of fluid dynamics.

 

I think the previous diagram is of the pre HE system. I came across the diagram of the HE cooling system that perhaps is the one Doug was referring to. It is on page 26-1 of the Jaguar XJ-S H.E. Supplement to the Repair Operation Manual, published by Jaguar in January 1982 as a stand-alone addition to the existing Repair Operation Manual. This was subsequently bound in with later editions of the R.O.M. copies come up on ebay from time to time, and I have found it a really useful reference. For example here is one for sale: Original Jaguar XJS Repair Operation Manual - Incorporating XJ-HE Supplement | eBay

Anyway, a copy of the system diagram is attached. If you read the narrative, item 8 (clearly the filler spout non-return) is incorrectly referred to as the thermostat jiggle pin - which are clearly separately shown as part of the thermostat itself, so this factory diagram is incorrectly labelled! The filler spout non-return valve is called a "jiggle pin", item 8. Looking at item 8 under a magnifying glass (age...) it seems as if the diagram of the non-return valve does prevent coolant from entering the banjo system! In fact there are TWO item 8s on the diagram, one in a little magnified circle is a close up of the thermostat and its blank-off attachment to the cross-pipe. The second item 8 is the actual cross-pipe non-return valve, while item 4 actually shows the thermostat jiggle pin.
So where does that leave us, there are errors in the labelling, so what do we deduce from the orientation of the filler spout air purge system non-return diagram, if anything?? I still believe, for my actual car, preventing coolant from entering the filler spout is best; but I would love to hear from someone who was involved with Jaguar's HE cooling system modifications from the pre-HE to know what their thinking was.
Greg

 

It is comforting to me, at least, that this diagram shows the thermostat (#4) jiggle pin and the filler neck jiggle pin (#8) both orientated to allow a flow of air, but not coolant, and as fitted on my, and some other members cars. Greg, I agree that it is best to STOP coolant entering the filler tube too.

I just looked at my old thermostat and the jiggle pin is physically as shown as it is diagrammatically and would allow AIR to flow in the direction of the coolant, but would close on a denser liquid so COOLANT will NOT flow through the jiggle pin from engine to radiator. Item 8, the filler neck jiggle is just listed as a "Jiggle Pin", and coincides with the function of the thermostat jiggle to allow AIR to be purged, but to not play a part in the overall cooling.
Now that I have reassembled all the hoses, I checked temperatures on pipes and resulting air in the system.
During warm up, the pipe from the left thermostat leading TO #18, the venting jet gets warmest first, the exit pipe back to the remote header tank, #3, is also warms up. The pipe FROM the banjo bolt on the radiator stays cold, and the pipe from the filler to the banjo stays cold. When the thermostats open, the banjo tubes get hot, but the filler to the banjo does not get hot, so I think there is minimal flow!

After filling, running, and letting the system cool, if I do not vent the system from the remote header tank, and just remove the center filler cap, the water level is to the top of the tube, and prior to running, it was down several inches, so air was either sucked out or otherwise forced out.

I think that air would be removed with the #8 jiggle orientated either way.

What I think the intent is, from the diagram, is that at operating or max temperature, the thermostats would be fully open, and they would be blocking the cross flow to the filler cross pipe (#7), This is also the inlet to the water pump. The inlet should be cooled water from the bottom of the radiator. With the #8 jiggle pin set to allow water flow from the banjo to the filler pipe, then HOT, uncooled water is being allowed from the radiator top banjo to the water pump inlet, reducing cooling efficiency.
Consider also that the cross pipe would have high water pump suction pressure, with the thermostats blocking the inlet to the cross pipe and the water pump sucking UP cooled water from the bottom of the radiator.

Overall, it would seem to me to be a bit of a solution looking for a problem and as is typical, more complex than it probably needs to be, but some engineer at the pub probably said that they needed to add some complexity to make the job justified to some manager?

I am happy with my rationale, and seeing that it does remove air from the filler, it seems to be functioning, but it may remain a mystery as to why go to the complexity of adding a jiggle to a filler neck to a 1/4" coolant tube that could hardly affect the cooling efficiency even if it did have coolant flowing through it.

And I agree that stopping flow to the filler is an aid to improving cooling.