My GQ keeps overheating

[Not-e-Nuf]

hi, i have a 91 GQ 4.2 Petrol, it has 225kms, auto and runs on 33's with duel fuel. It has a brand new radiator, new thermo, new fan, auto box oil external cooler - all done in last month but it still overheats. but i'm talking hitting redline within driving 2-3km down the road. mechanic and i have no idea what it could be. Some people say that maybe the gauge is stuffed but you can hear the coolant bubbling and see it in the overflow bottle.
Any ideas would be great!!! as i don't want to spend anymore money unnesscarily.
thanks

[IN24BZ]

check the water for oil and vice versa, do a teekay head check on it as any reputable mechanic shop will have this , sounds like the head will be cracked around the valve guides to be as it a common TB42 problem..... being a nissan tech id venture a guess on this..

[bogged]

hi, i have a 91 GQ 4.2 Petrol, it has 225kms, auto and runs on 33's with duel fuel. It has a brand new radiator, new thermo, new fan, auto box oil external cooler - all done in last month but it still overheats. but i'm talking hitting redline within driving 2-3km down the road. mechanic and i have no idea what it could be. Some people say that maybe the gauge is stuffed but you can hear the coolant bubbling and see it in the overflow bottle.
Any ideas would be great!!! as i don't want to spend anymore money unnesscarily.
thanks

Is the water pump fucked, not pumping water?? Air blockages in the system - I had an airlock once, and this happened..

have you had the engine flushed?

[kebwaa]

you didn't mention it in the list of things you did, but have you done the thermostat. if so i would probably go with the head problem too.