I have a stock 2003 Honda civic LX. I took my header to get refurbished and got all the sealing parts i bought new and installed everything correctly. Still I get the same problem, the car turns on and stays running for about 10 minutes then it starts coughing and dies off. This problem started after I took out the whole engine and transmission together because I needed to replace the transmission. I never did anything to the engine or header, I installed everything and turned the car on. it worked for a few minutes then died off. the manifold got flooded with water and the spark plugs got wet with antifreeze. I clean the spark plugs then re-install them and the car turns on every time but always ends up dying off with the spark plugs getting wet with antifreeze. The problem stops if I drain all the water and turn the car on like that, but it obviously overheats. Can anybody help me out with this? Any idea of what is going on? I would greatly appreciate any help. Sorry about the long story

 

It's either a part leaking on the intake manifold, or a bad head gasket or cracked engine. Do not run without the cooling system completely full.

A pressure test might help to diagnose. This test involves replacing the radiator cap with a pump to put the cooling system under pressure with the engine stopped. Look in the manifold and cylinders to see where coolant appears.