Jaguar, you find it all over! Well worth removing the wing, another potential rust disaster averted.

 

Very true statement - and all thanks to your suggestion on cooling or I would never have done so - I also looked at the points where I should close of the top of the windscreen pillar and I spotted something else to fix - my windscreen surround rubber is perished / rotten .... I really need to stop adding new jobs faster than I can knock them down but now I've seen it the OCD will not allow it to be ignored.

 

Vacuum reservoiir moved - it now sits under the right hand wing - well it would if the wing were fitted - those wonderful thoughtful people at Jaguar even had the holes on the left - just needed to knock the corner off the support bracket. All the nasty rust on the right below the wing sanded, treated and primed

 

Now sits under the LH wing, Ben? Either way, well done!

 

Oops - my bad - yeh the left -

 

So what happened so far - well a tank I ordered wasn't up to snuff, another tank I ordered same deal so I had one made to suit my needs at OBP (OBP) all credit too them. Images below, although you can't see it there is a hole to the right where a level sensor will be fitted, tank is 1.5 litre so just about big enough. The bottom rests on rubber (a hose cut down its length, the mount is something I drew up and printed, it is clamped in place using the original washer bottle clamps, I have the various bits to introduce the hose - a 20 to 16mm elbow, I've also introduced a T with a bleed into the heater hose - at least I will, the bleed from this and the radiator to the top of the tank is designed for 6mm ID hose. The goal here is to bleed from the heater top hose to the top of the tank in addition to the radiator bleed. The original Jaguar bleed and 'fill' pipe will not be used, nor will the expansion tank or recovery tank.

BUT - and the reason for the post - I can't decide whether to utilise the metal 16mm pipe running on top of the left chassis rail (can be seen below) to the bottom connection of the heater - this is slightly too long to introduce the 16mm T for the expansion tank - should I cut it and hack weld some bead onto it or refabricate it in copper - I don't care for, or understand why it is bent how it is anyhow, I've tried it the other way around and it just doesn't seem to follow the path I think it should. Clearly this location is in proximity to the exhaust, probably why Jaguiar made it from metal in the first place. I'm leaning toward making up a new pipe but I lack the swaging tools to introduce a bead on the ends.


This is the tank in situ. The support is a printed item in PETG so it is pretty strong and will take a fair amount of heat - again I'll see how it behaves - I can always print another and heat proof it but the only real heat in this area is really radiated from the exhaust and I've had that ceramic coated (crazy money) but a bona fide coating used in motor sport - not an ebay rattle can.




Float switch for Tank


General view so far - note the pipe on the left chassis rail (right side of image). Various bits going in but held up waiting on parts - namely the washer bottle and 'stuff' so I can't deal with the engine and cross member until I get all the wet work done in the engine bay. Yes I know I haven't put the clips onto the brake reservoir hoses yet but I have replaced and re-engineered Jaguars bits in favour of my own. I am fabricating an metal tray to sit below the reservoir to catch and guide fluid away from the bulkhead / chassis - this will use the same bolts as the reservoir and sit directly under it - not that I plan to use pour and pray techniques for filling the reservoir. The blue straps make sure the temporary garage stays put in high winds ...


This T will go into the heater top hose to bleed that. I may simply replace the barb with a bleed screw but I'll see how it works in practice.

 

Ben I need a diagram to make any sense of your question:
"I can't decide whether to utilise the metal 16mm pipe running on top of the left chassis rail (can be seen below) to the bottom connection of the heater - this is slightly too long to introduce the 16mm T for the expansion tank - should I cut it and hack weld some bead onto it or refabricate it in copper - I don't care for, or understand why it is bent how it is anyhow, I've tried it the other way around and it just doesn't seem to follow the path I think it should. Clearly this location is in proximity to the exhaust, probably why Jaguiar made it from metal in the first place. I'm leaning toward making up a new pipe but I lack the swaging tools to introduce a bead on the ends."

Second point: The bleed from the heater hose will be redundant, IMO; BUT, I assume you will be connecting the right hand side spigot in this photo to the radiator bleed banjo?

I ask because that spigot looks a bit large in I.D.What ID pipe are you going to use to feed it? I ask because it should be VERY small, max 3mm ID. This is because it needs to ensure that the minimum amount of hot coolant from the radiator bleed can short circuit the radiator cooling by going via the header tank and straight back to the engine via the heater return pipe that feeds into the bottom hose.

 

This is very quick and dirty. You actually need some circulation in this 'bleed', that's how it works as the air can go too the expansion vessel but once there is stuck, the bleed on the vessel has a pipe that goes below the coolant surface almost to the tank bottom.

If you look at the original the system relies upon water circulating through the expansion vessel - it is connected between the top of the radiator and the pump, this pulls coolant through the tank, the goal being for air to enter the tank but never leave, thats why Jaguar got away with this, this air should then be pushed out into the recovery system which also contains coolant that is drawn back - the system should self purge but it is complex and depends on many things being just right. I've not figured a simple way to do this circulation bit. I'm semi relying on differential pressure to ensure air gets to the top and stays there simply because the tank will be the highest point in circuit, I selected 6mm ID for the purpose, I can always make up a restrictor to fit into the hose. Since it is a closed system even if some kind of negative pressure is created at the radiator it cannot pull from anywhere except the heater top hose via the expansion tank so the heater may be slightly less effective but the engine cooling will not be impacted since coolant flows this way in any case. I've really not decided what to do with the pump inlet that goes to the original tank but I'm of the opinion currently that I should also T the bleed into the pump but I will see how this all behaves, as it stands I can always just put a bleed screw into the heater T and circulate through the tank in exactly the same way as per Jaguars original. I can't be 100% sure but I think heater efficiency may to some extent depend on this additional pump connection to drive the circulation via the crosspipe, I may T off the heater return. Yes I still have plenty of what if's to explore - totally incapable of keeping it simple.

 

Ben
There is absolutely no need of any sort to connect anything to the pump. Indeed I think you might mess up the simplicity and efficacy of having a "higher than engine and rad" header tank. The 6 litre cross pipe does not even have a spigot for this purpose. You should be able to get rid of the entire OEM purge system components and just run a bleed to the header from the radiator - just as Jaguar did on all the V12 saloons where there was room for a higher than engine header.
If you have a spigot on your cross pipe block it up, connecting it to the header will be pointless and probably mess up the circulation. On the OEM setup that "question mark" pipe from the header to the crosspipe is there to drain the header tank back into the coolant system. This is because the OEM header is continuously filling up with coolant from the powered purge circuit operation, and the coolant has to get back into the main circuit.
Remember, that diagram you posted is not accurate (component 3) there is NO connection on the HE engine from the header tank to the heater return pipe. That is why the question mark pipe is there.

 

Agreed - and I can't remember how things were - no picture of that 'stuff' - I don't actually have the new crosspipe here - so if there's no connection this is just me overthinking as usual, all my 'stuff' is supposed to be shipped this week so as usual I'm planning, re-planning, reconfiguring and all in a vacuum. My only concern is the purge of the heater which seems to be the place things get messed up. I do have a vacuum bleed tool that is mandatory on a couple of the cars I have I just don't want to collapse the radiator - I've seen air pressure kill large commercial tanks, I've never used it on brass / copper radiator.

I saw some good shots of the area in a Harry's Garage you tube video - that XJ coupe he has is a beast - and it only cost him 70k .... here is a link for anyone that hasn't seen or heard his V12 animal ..