Quote Originally Posted by jaypee10 View Post
hindi naman dapat pinupuno ung reserve tank...
Several things.

1) If from a cold start and you encounter coolant spewing out of your radiator filler neck, then its likely your cylinder head that's going to need work.

2) If on the other hand this happens only when you're running there's a good chance your coolant loop is heavily silted and corrosion has caused blockages in your tubes. Replace the radiator.

I don't think the air filter did anything to your engine unless you're burning really really lean and that your radiator is already compromised.