air in cooling system

[allencr]

Does the coolant overflow have 2 lines coming out of it? if hooked up wrong, it won't pull coolant back into the engine.
The bubbles have to come from combustion or hot spots. The hot spot/s from low/slow coolant flow can happen from blocked passages, wrong HG or badcooling system setup.

[sainz]

Does the coolant overflow have 2 lines coming out of it? if hooked up wrong, it won't pull coolant back into the engine.
The bubbles have to come from combustion or hot spots. The hot spot/s from low/slow coolant flow can happen from blocked passages, wrong HG or badcooling system setup.

cooling system is al factory and looks to work ok.
as far as head gasket its new metal type the head was done up aswell.
i have decided to bite the bullet and tell him to go ahead and pull it apart.
if its workmanship he will fix it . if other well.
most people i have told think its the head cracked.

[MWP]

I just had a problem with mine where the tube in the overflow bottle had a hole in it near the top and was sucking up air.
So thats another possibility.