I have a 98 Honda civic ex that is overheating when I get up to highway speeds.when it just sits and idles or I am only driving below 45 mph it does not overheat.i just changed practically the entire cooling system with the exception of radiator and cooling fan.i just replaced the radiator two years ago but did pull it out flushed it and water flows freely through it and the fan is working fine as it kicks on and off like its suppose to.i changed the water pump/gasket thermostat/gasket fan switch on thermostat housing temp sending unit on front of motor and both rad hoses.i have tried "burping" the system thinking maybe there was air in it but to no avail.i have tried a compression test on all four cylinders trying to check for maybe a blown head gasket or cracked head but compression seems fine.not sure what else to check.anybody have any suggestions.would be greatly appreciated.

 

Have you replaced the radiator cap? Seems like u done everything else to prevent the overheating.

 

yes I did we replaced everything ended up replacing head gasket and that solved the problem thanks

 

When does the engine overheat - under what conditions?

Describe how you bled the cooling system.