when refilling the coolant, is what fills to the top of the tank, or you leave about 1 "(3 cm) of free space to allow for expansion?

 

I have 1" of air space under my cap the 'Low Coolant' message shows on the dash.....i loaded half a tank , i have fear that expote by pressure .

 

In my car, half a tank does not show a low level warning. It could be that your float sensor is stuck or needs replacing.

There is a brief description in this thread:
https://www.jaguarforums.com/forum/x...nt-low-100966/

 

New sensor, new tank, new cover.

 

Anything below the neck and my low coolant light goes on. So I keep it filled right to the bottom of the vertical neck.

 

The correct coolant level is to the bottom of the filler neck on a COLD engine:



(click on the image to enlarge it)

There is no need to leave free space for expansion. As the engine heats up, excess coolant goes into the Atmospheric Recovery Bottle behind the front wheel arch. As the engine cools after switching off, it is drawn back into the Expansion Tank again to maintain the correct level.

Graham

 

I can not keep you full, below 3 cm, never try to fill all things. air chamber?

 

The XK8 should NOT use coolant. If the level drops by 3cm after you fill it up there must be a leak.

Have you done any work on the cooling system - replaced a hose or the thermostat?

Graham

 

Overflow will be returning liquid to the tank? complete filling is necessary for this? I have all new. thermostat, tank sensor, lid, liquid, no smell of engine coolant. google translator

 

Yes - liquid is returned to the tank.

It's easier to explain the liquid flow with a diagram:



As the engine warms up, the coolant expands. Excess liquid from Coolant Reservoir (item 1) goes through Expansion Hose (item 8) to Atmospheric Recovery Bottle (item 11).

As the engine cools, the coolant contracts. The resulting vacuum draws liquid back from the Atmospheric Recovery Bottle (item 11), through Expansion Hose (item 8) back into the Reservoir (item 1).

This is why the level in the Reservoir (item 1) should always be up to the filler neck - no coolant is lost.

After changing the thermostat, you could have air in the system. It's important to fit the thermostat with the bleed hole (arrowed in the following diagram) at the top:



This allows the air to bleed out.

Graham

 

GGG.. thank you very much for your time, very grateful. I understand now.

now I'll fill neck level until ...

 

If you still lose coolant, check the Atmospheric Recovery Bottle (yellow arrow) is not broken and the Expansion Hose (red arrow) has not come off:



You have to remove the right hand black plastic wing liner to see the Atmospheric Recovery Bottle.

Graham

 

filled to neck level cold 2cm below. fill again and test. ok overflow tank.

 

again red low coolant light, is a secret to the atmospheric recovery tank ? or cylinder gasket burned ... new tank thermostat. temperature ever red. slight misfire few seconds on every start .... some relation?