1st Winter Job – Atmospheric Catchment Tank tidy up

[AndyF]

Hello all,

I thought I would share the results of the last few days tinkering! Following the last run out of the year for the XJS to Palé Hall in Wales (https://www.palehall.co.uk/ - thoroughly recommended!), I noticed that the warm air from the HVAC system was not constant – I kept having to turn it up.

On further investigation when I got home, I found that the coolant level was somewhat down on what it should have been -> the expansion tank (mounted on the LHS of the engine bay) was almost empty. This was most odd, as the coolant level under the central coolant filler cap was the regulation 3in below the seal when cold. Perhaps the system wasn’t purging properly?

So I started at the end and worked backwards. Atmospheric catchment tank (ACT) vent in LH wheel arch? All clear when blown through with an air line. Purge tube between expansion tank and ACT was also clear – but strangely didn’t bubble when air went down the tube?

I wanted to check the ACT, so removed the LH wheel arch liner (some slightly resistant screws and 25 years of crud!) and exposed the ACT.

It was completely empty and didn’t even have any sign of old coolant or sludge in it. I removed the ACT, cleaned it and then cleaned the wheel arch cavity – overall in pretty good condition (remarkable!) with only some minor surface corrosion.

[AndyF]

Continued...

I then checked the expansion tank cap – the original having been replaced with a new OEM 16 PSI cap a couple of years ago

and checked that the purge valve in the centre of the cap worked.

So my conclusion was that the cooling system needed a proper bleed. I cleaned up the ACT and wheel arch area and then set about putting it all back together.

I refilled the ACT 25% full (~1 litre) with 50/50 Bluecol 2 year antifreeze and summer coolant / de-ionised water (having double checked that the current coolant fill was Jaguar OEM coolant which is ethylene glycol based so there would be no issues with mixing coolant types (IAT / OAT etc)) and then filled the cooling system using the KWE technical paper on filling and purging the V12 (https://www.kwecars.com/wp-content/uplo ... lBleed.pdf).

It was very confidence building that I could feel heat in all the cooling pipes I checked, including the bleed system on top of the rad and the heater matrix pipes, suggesting that all is working as it should. It was also good to feel the HVAC blowing nice and hot inside the cabin, suggesting that the temperature issue was not HVAC system related.

1 observation on the KWE guidelines – yes, it really does pour out of the bleed hole when all the air has gone (so excellent advice about goggles and plenty of absorbent towel to catch the excess and protect yourself and the paint)!!!!!

Once the system had begun to cool I could see the level dropping in the ACT (by about 10mm) as coolant was being sucked back into the expansion tank – a great result! All that was left to do was to remove the road wheel, refit the wheelarch liner (making sure to apply plenty of black sealant along the lower and inner edges where it mates to the body) and stand back and admire another job ticked off….fingers crossed that this resolves the unstable hot air issue on the HVAC.