I have a 2003 honda civic ex 5spd. A couple months ago my heat would stop working when I was stopped at a stop sign or red light and then start working when moving again. It wouldnt blow hot air when starting the car in the morning until I started moving. I checked the coolant in the reservoir and it was on full so i figured the rad was full and it wasnt the coolant. Then one day I checked the rad just to make sure and it was almost empty but the reservoir was still full. I filled the rad up and my heat started to work but every few days the rad will be low on coolant and stop heating again but reservoir will still be full. The oil is a good color and to the right level, no smoke anywhere, or any leaks anywhere. My accessories belt also squeals when turning the heater on and I was wondering if this could be the problem, that it just needs tightened, or a hose is letting air in, or if its a blown head gasket. Someone told me its most likely a bad gasket but I have no other symptoms, so Idk. Has anyone else had this problem or know what it could be before I take it to the shop?

 

Check carefully for leaks to the outside. There are hoses on the back of the engine that are best inspected from underneath. Get the radiator completely full, then start the engine cold with the cap off and rev it. If a bunch of bubbles come out that is likely a blown head gasket. If it's not that, the radiator cap could be bad preventing coolant from returning from the reservoir. The seal at the upper outside edge is important for that. Also the hose between the radiator and reservoir must be airtight.

 

alright ill def. have to do this tomorrow. another question, if it was a bad head would it put my car in limp mode?

 

alright so I went out this morning and took the radiator cap off and made sure it was full, I started the car and it was fine but when i press on the gas coolant shoots out. Does this automatically mean its a bad head or could it be something else, since its fine when its idling?

 

That is very typical of a blown head gasket. There is not nearly as much pressure in the cylinders when it is just idling.

 

alright thanks for your help