Hey guys! So i bought an eg civic in october with 230k miles and after a month of having it, i started having overheating issues. After driving it for a while, the temp gauge would go up and every once in a while go back down. I was told might be a head gasket so silly me decided to put head gasket sealer in the cooling system. ended up clogging it up. just last weekend, i flushed the cooling system but now when i drive it, after it warms up, it idles for about two minutes fine then the gauge starts going up again and it idles really low like it wants to die. does anyone have any ideas what it might me and how to fix it?

 

Is the fan coming on?

When running and at operating temp are both radiator hoses cold? If yes, then the waterpump or the radiator is bad. If it's the waterpump the go ahead and do the timing belt and tensioner too. If no, then you need to look into the headgasket.

To check for the headgasket you need to test the coolant for exhaust gases (they make a tester) or if it's oily and check the oil for water (looks milky). If those are good, check compression and, if there is loss of compression, then leakdown test to pinpoint the cause (which will probably be the headgasket).

 

Top off the coolant in the radiator and reservoir and bleed the cooling system.

https://honda-tech.com/honda-civic-d.../#post38664177

If the problem persists, rent a block tester kit from AutoZone and pressure test the cooling system.