One of the most common problems is that you simply have a header gasket blew out somewhere, our as previous stated a valve tick. First I would check the header gasket when you start the car and see if the ticking sounds like it's coming from there. If you have to get a new gasket I'd recommend the Aluminum gaskets. You can buy them from summit for around 40$ and they say on the package their reuseable but I havent got to test that out yet.