I have a stock 2000 Civic Ex, I was doing a tune up and had trouble removing the pvc valve. It eventually broke and I had to remove the intake manifold so I could get to the breather chamber box so I could get the rest of the pvc valve out. I put in a new manifold gasket and put everything back together. I then added coolant to the radiator and after starting it up the engine was idling weird and the coolant was shooting out the muffler/exhaust. Anyone have any idea what I could of done wrong? Hope someone can help.

 

Sounds like you swapped a coolant line with a vacuum line.

 

1 of 3 thing most likely.
1 you bolted the intake mani down wrong and coolant is leaking into the intake. You need to bolt the mani down starting in the middle and working out in a cross pattern.
2 your head gasket is blown and coolant is getting into the cylinders. Do a block test.
3 You hooked a TB coolant line going to a vacuum line
Also keep in mind that is 100$ normal for water to come out the exhaust just the the motor running and the combustion compression process. Not a ton of water but you can get a decent drip. It should be fair clear water though not green coolant.

 

Thanks for the tips. I bolted the four top bolts then the bottom three. The coolant is coming out green right now. I guess I'm going to have to pull the manifold tomorrow and inspect everything. How can I do a block test?

 

I would suspect a head gasket last... I would start with checking to make sure all the lines are hooked up right.