Well, my accord has another cooling system problem. I replaced the heater core last month (what a pain in the *** that was!) and now the cooling system is closed and leakfree. Recently my coolant level has been dropping with no visible leaks (no steam or sweet smell from exhaust) when driving on the highway the coolant forces into the overflow and after an hour the temp guage shoots up and i have to pull over let it cool and top off the radiator and empty the overflow. Both hoses are tight and hot when at temp. no oil in coolant and no coolant in oil. occasionally boiling can be heard and bubbles coming up in the overflow bottle. i am using a 50/50 mix that is a month old.

Im considering the possibility that the thermostat is not properly opening and closing or the cylinder compression is leaking into the coolant system.

any input is much appreciated.

 

T-stats are cheap, suggest dealer, to replace....along with the rad cap.

From there be sure you properly bleed the cooling system.

Let us know what you have from there.