My TDV8 is bubbling air in the header tank ? , Done the block test and the fluid doesn't change colour so it's saying there isn't co2 in there ? . Also it isn't using water or loosing water and there is pressure still in the header tank in the morning ??..

Are you sure?

There is a fluid bleed off screw on the top of the tank, could this be loose?
Where are the bubbles coming from? There is a pipe to the top of the tank and one to the bottom as well, the one at the bottom can chaff, and leak which could suck in air.

Are you removing the cap cold every time? Because if you remove it when the fluid is hot then again at a different temp you will get a different standing pressure in the header. Remove when cold in the morning, then only again the next morning when the ambient is the same.

But you shouldn't be able to have a high pressure and a leak at the same time.

it's likely air from the header tank being sucked back into the system through the top hose as the pressure drops, then as the pressure rises it bleeds back into the header. If you aren't losing fluid, have no co2 in the header and don't have contaminated oils, then I wouldn't worry.

That's my take on it, but someone may come along with another idea  There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
Fiat 500x 1.4 multiair Lounge 2015
2010 LR D4 Commercial 2.7 TDV6

Last edited by northernmonkeyjones on 3rd Apr 2016 8:47pm. Edited 1 time in total

Yeah the bleed screw is tight for sure , The air is coming from the top mainly but does also come from the bottom too . I dont have a leak just air consistantly bubbling mainly in the top pipe that comes from the top hose..

Just to check is the coolant pink? There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
Fiat 500x 1.4 multiair Lounge 2015
2010 LR D4 Commercial 2.7 TDV6

Just bought it like it (knowing the issue) it just has water in it..

It needs proper coolant, it can take a while to self bleed. If it hasn't got pink in it then the coolant has been dropped out and needs replacing. It will slowly bleed out the air after it has been changed. Get the water swapped for some propert OAT pink coolant and run it for a while, to see what happens, it should stop bubbling once all the air is out. There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
Fiat 500x 1.4 multiair Lounge 2015
2010 LR D4 Commercial 2.7 TDV6

How could the bottom hose in the header tank cause air to be sucked in if it was under pressure or is that pipe not under pressure ?.