I changed the head gasket about a month ago.
With help from friends at home.
Cleaned surfaces of head and got it check if it had to be machined or not,they told me it didn't need machining,so I bought a new head gasket and proceeded to change it.I followed internet advice and followed the workshop manual.
I used a torque wrench for all bolts.The instructions on the head gasket box said to readjust at 1000 k/m.
I drove 924 k/m and the same thing happened again,engine stated to overheat. When engine cooled I refilled the radiator started the car and as the engine heated up the radiator started to bubble.There is no sign of water coming out of tailpipe.
I adjusted the head bolts to 49nm,then tightened bolt a further 90 degrees.
I didn't coat the head with any compound.
I also changed the water pump a new thermostat and radiator cap.
Does anyone know of something I could have done wrong.
If you need more information please ask.
Thank you for your help.

 

check the head for cracks? was it magnafluxed? or just visually checked?

 

Probably either a slight warp in the head or a cracked head. When you checked it out did you use a feeler guage and a good straight edge or just eyeball it. If the aluminum head warped (and they always do when they overheat) you won't be able to see it unless you use the right tools. I'd take it back off and have it resurfaced by a machine shop and ask them to check for cracks. Magnaflux is only for iron heads but they use a dye or something for aluminum heads. Ive been through all that $*#+! many times. Good luck with it