Running hot

[Martin110]

My 300TDi is sitting between the middle mark and the hot. I found the other day my expansion tank had a small pin [ed - prod with a sharp implement] hole in it not allowing the system to pressurise. When i was topping up the coolant i noticed in the thermostate housing that the level of coolant inside was very low. Would lack of coolant inside the thermostate house damage the termostat and cause it to run hotter than before?

I have since replaced the expansion tank for one that doesnt leak like a sive and it is still running hot.

Was thinking of changing the thermostat to make sure seeing as its a cheap and easy job.

[biggerlandy]

take thermostat out and replace it or as a quicky take ther out remove the stat bit in middle of it so its full flow as a test bleed the system it should take ages to get warm normall etc if all ok then just the stat is u/s if it gets hot still check pump or head gasket oh and the little plastic y bit inbetween rad   tank   ther housing check its not blocked as this makes it overheat if blocked

[TDi90]

replace thermostat. £3
and replace sender for a DEFENDER type... £3
sorted.