I just rebuilt a d15b7 engine out of a 94 civic dx. I took it apart a few months ago and just now hot back to it. I assembled the engine and started putting everything back on it. There is a hole in the back of the block, maybe with about a 1 inch diameter. I am almost posive that it is some type of breather. There is also a vacume line coming off the bottom of the intake manifold to right above this hole. It looks like a 90" peice with a 1" part on one side to go into the block and a smaller part on the other side for that vac line to slide onto would work. I lost whatever this peice is and need to know what i need to order to replace it. Anyone know?

 

if it to the right closer to the bottom of the block then its a breather box for the PCV (Positive Crankcase Ventilation). if its to the left its a drain plug for coolant i think!

 

it is the breather box for the pcv system

 

I only know this b/c I'm doing this maintenance today: The drain plug for the coolant on a D15B7 is under the exhaust manifold at the front of the engine, towards the passenger side... not at the back.

 

could be different on a b series, but on my b16 there are coolant plugs on the front and back of the motor. 19mm socket, about an inch sized hole. it sounds to me like the pcv breather box. dunno what else it would be.

best of luck.

pics?