Insignia loss of coolant no leak

[graham8]

Mate has a insignia 2.0 diesel which is losing coolant and has to top up every 200 mile but no signs of a leak. Car isn’t overheating and is driving well. Anyone had this problem before?

 

[gary1365]

Egr cooler

 

[Stu Beck]

It could be a small leak that’s just drying off before it drips. I’d guess the water pump.

 

[NI_Volvo_Nut]

If its an Auto, stop driving until you find the leak, the transcooler runs in the rad and fills the transmission with coolant when it goes. As already said, EGR cooler would be another contender. Topping up every 200 miles is quite a leak so if external should be easily found.
Any pressuring in the cooling system? If so could be head gasket issues.
Find a mechanic to check before you do damage

 

[stevyg]

It could be a small leak that’s just drying off before it drips. I’d guess the water pump.

This or a crack in the block. See if you can see rust in a random spot on the block.

 

[Manover50]

Some insignias had dodgy header / expansion tanks that had the tiniest cracks on the ports for the hoses.
All you ever noticed was a slight dry powdery tear but lost about half the tank every 100 miles.
They also have plastic thermostat housing so that's another weak spot.
First off.... If you can find someone, get the system pressure or dye tested.... Then if a stop start system get the transmission oil checked for coolant contamination.