Abnormal Water Loss

[Metallic2001]

My brothers radiator seems to be going dry after a day of driving. The radiator, and water pump was replaced a few months ago. He took it to a radiator shop and they couldnt find where it was leaking and we let it run for about 30 minutes and shut it off and look for leaks but never found anything and the next day after coming back from work it was dry again...there is no water in the oil so we dont think its a cracked head. Does anyone have any ideas about what would cause this.

 

[jimbo74]

a leak in the system would cuase that.... put it on a coolant system pressure tester.... and test ti to 13 psi.... the reason for this is that sometimes when things warm up, they might swell and seal up a leak... maybe it leaks out only when its cold...