The small plastic valve that fits in the bleed pipe below the middle coolant cap. Are there any consequences for not having one or are they essential

 

Absolutely essential

Absolutely not essential.

You get to choose

Search the archives using "EAC4126" and/or "EAC4168"

The need for this valve, and correct installation, and actual intended function, have been confounding V12 owners (well, some of us) for a long time. I removed mine and never looked back. Good idea? Bad Idea? Hell, I dunno !

Here's one conversation:

https://www.jaguarforums.com/forum/x...-0-v12-149397/



Cheers
DD

 

Rex
The Great Palm discusses it. I have, pre my coolant system simplification, tried:

• with the valve in place preventing fluid going from the spout to the banjo
• with the valve in place preventing fluid going from the banjo to the spout
• no valve.

No discernable difference at all between the three. Jaguar HE coolant diagrams show the valve should be installed to prevent coolant passing from the spout to the banjo. But they call it a "jiggle pin" not a valve, so maybe it was there to sort of prevent a steady flow rather than be a real one-way valve?
My advice is forget about it and remove it.

 

Thanks all, I think I will depose of it. A couple of years after I bought the car I removed the small hose and the valve body was in place but the jiggle pin was missing. Never did find it. But I fitted a new one so water could flow to the banjo. Now I'm changing the small hose and I had fitted the new valve into the hose as I had fitted a later crossover pipe and the valve wouldn't fit in the filler neck.