'99 honda civic 1.6 ltr 4cyl. it has new water pump,,no thermostat,when full of water i can drive for about 25/30 mins.temp sets about half way,,all at once temp. will jump up in the red,,mostly all water is out of radiator when i shut it down,,,timing is set perf..no water in oil,,no smoke,,not skipping/missing..was thinking maybe head gasket,,but no signs i'm familiar with,,and when running can't detect no leak

 

Top off the cooling system with fluid and let the engine idle with the hood open for an extended period of time. Watch carefully for leaks. Turn the engine off if when it begins to overheat.

Reinstall a good thermostat. Running without it is bad for the engine.

 

i understand running without thermostat is not good,,but putting a new thrmst back in is not going to stop it from overheating,,as it did with and without thrmst