It is polyethylene, or 'poor man's Teflon' and it does not play nicely with glue. You might be able to use some melted PE to fill in the crack but the really great news in all of this is that a new tank is only about $20, and even less at Ron Ayers ($15). My suggestion would be to buy a new bottle and be done with the leak because my experience with PE is that it is unworkable.
Also, you will want to move that P.C. ground wire up to the frame brace where the wiring harness is attached. Use the same bolt that is there holding the clip that the gray harness is attached to.
I know the instructions with the P.C. say to use that bolt but it is a terrible idea; using a plastic flange under a steel bolt to hold an electrical connection wire. At best the plastic will squeeze or flow out from under the bolt head, leaving a lousy ground and at worst the plastic will crack as in your case. Not your fault though as you were following directions.
Brian
I am changing coolant again, to get rid of the water wetter. Checked the coolant overflow bottle after refill, per service and noticed a leak. I think it has been there since I installed the PCV. I obviously overtightened the lower bottle mounting screw in order to insure a good ground. (or you non PCV users, the PCV installation isntructions suggest using this screw as a gorund)
I am trying some 2 part epoxy but after applying I noticed on the tube " will not bond polypropylene or polyethylene" I am wondering if anyone knows waht the bottle is made out of?
It has the markings:" <PE> on the side of the bottle