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Ok, so i overhauled cooling system twice, recored radiator twice, and literally inspected each piece of it, all tanks, hoses, metal lines were out, cleaned, painted. ETC
I was following Grant's "V12 cooling system maintaining" manual located here word to word https://www.jaguarforums.com/forum/x...aining-219536/
And by doing so, i also put transparent hose between metal and plastic tank and also prefilled plastic tank 1/2 and hose is cut at 45 degrees at the very end.
Please note i drained the system 5 times and filled it up 5 times using different methods.
But anyway, that hose always empty! , when car is fully warmed up, hose is only 1/3 filled with coolant from metal tank side and a few inches from the plastic side
please see bellow
when car is cold, hose is empty, only plastic side has some of coolant.
And on top of that, after each test run (40 miles in total)
level in plastic tank drops, it was 1/2, now its 1/3, but coolant level in central cap is up to the top always.
Its really strange, coolant is always up to the top, when car warms up this coolant should push all the air that was in that hose after install to the plastic tank and out, then it should suck coolant when cold, therefore that hose should be always full of coolant and plastic tank coolant level should remain the same.
The pressure cap on the steel tank is NOT sealing 100% to atmosphere, so it sucks air on cool down, easier than heavy coolant.
The same for the filler spout cap, although coolant dribble there would be seen.
One of mine did this after my own rebuild. Took weeks, and eventually it was the NEW CPC Aussie pressure cap on the steel tank. rated at 13psi, it was blowing off at 4psi.Went to work and tested dozens of caps in stock until I found 2 that were within spec, one for the car, one for the stash. Problem solved, a $12 cap, DUH.
Another culprit is the heater tap. They do not always leak OUT, but allow air IN on cool down, mongrel thing.
The list goes on, and it will be something really simple in my opinion.
The pressure cap on the steel tank is NOT sealing 100% to atmosphere, so it sucks air on cool down, easier than heavy coolant.
The same for the filler spout cap, although coolant dribble there would be seen.
One of mine did this after my own rebuild. Took weeks, and eventually it was the NEW CPC Aussie pressure cap on the steel tank. rated at 13psi, it was blowing off at 4psi.Went to work and tested dozens of caps in stock until I found 2 that were within spec, one for the car, one for the stash. Problem solved, a $12 cap, DUH.
Another culprit is the heater tap. They do not always leak OUT, but allow air IN on cool down, mongrel thing.
The list goes on, and it will be something really simple in my opinion.
Got it, that would explain why the hose is empty, but where coolant goes from plastic tank, and why level in the system is full, if its sucks air?
Thank you anyway!
Another thing to note, i pressure tested whole system (from center cap) at 15 psi , and it was rock solid
Paul
I think the OP meant that when the cap was replaced with the pressure tester cap, no leaks were found. So by elimination the original cap might be leaking pressure to the outside.
12-19-2023 | 06:29 AM
Coolant loss from plastic tank
