M42 Thermostat question??

[Sparkysparks]

Guys, my temp keeps going up wild high and making the pipes solid, as if the HG has gone, (we changed it the other week with a new head aswell)

Every now and then my heater would stop blowing hot air, as if there is no hot water getting to the matrix. When i changed the thermostat as i thought that was the dodgy bit it came with a different O ring, one that went on the rim of it instead of infront like the original. It made it just as bad, so ive taken the O ring out for now and running it colder than normal,

I was after fitting instructions as this cant be right
Pictures if possible

Thanks guys
Mark

[Luca318is]

you have to bleed your radiator, for sure you have air in the circuit and you need to get it out!

[Sparkysparks]

Ive bled the rad and its still got the same problem, now that the o ring is out of the housing ive got hot air in the car, so its got to be the thermostat blocking it, but surely this isnt right