Since the "closed system" bottle is the highest part in the cooling system and coolant should always visible in the bottle, the rad should always be full as well. On a "open system" the rad cap should be the highest part in the cooling system (so air will bleed) and the 2 valves in the "open system" rad cap must both function correctly. I've seen plenty of "open systems" where coolant level in the bottle was fine, but the rad was almost empty, due to a bad rad cap . With an open system, one must remove the rad cap to insure the rad is full.....with a closed system, all u gotta do is look at the bottle to insure the rad is full.

 

hm, the wifes grand has the overflow bottle above the radiator cap, i was pretty much modeling my swap after her system. she has an 04 grand with the 4.0. will this effect the system? having the bottle slightly higher than the rad?

 

If the bottle is pressurized, the bottle needs to be the high point.....if the bottle is not pressurized, the 2 valve rad cap needs to be the high point.

 

The set-up I have came out of a 93 and it works just the same as the Renix but has a lower kick on point somewhere around 160-180 degrees. Your best bet though would be the have a radiator shop add the bung to your radiator for the factory set-up(if possible). I had to do my cooling system swap on a budget and utilize parts on hand.