[Southpa]

Heres an overflow bottle I installed years ago when I learned that the lower 1/4 of my rad was plugged. I didn't have the time (or the funds) to replace the rad til later. Temp was going as high as 260 deg. and she was puking massive amounts of coolant. OUCH! But that sure says something about the original 1970 350 in my truck, shes still holding her own!

Anyway, the bottle is from a 1982 camaro, it mounted nicely on the inner fender with 2 screws. See where the tube goes into the top of the bottle? That tube continues (as part of the bottle) down to the bottom. If you find that your coolant level in the rad is down a little every time you check then your system is not totally enclosed. Air is less dense than coolant so every time your engine cools down (and coolant volume contracts) you are sucking air back into the system. The cap on the bottle has to be vented or the bottle will get crushed when the coolant contracts (negative pressure in the bottle is less that atmos. pressure) and/or explode when the coolant expands (positive pressure in the bottle exceeds atmos. pressure).

Check under the truck for any signs of coolant dripping when you shut down after driving. Thats when temp and pressure is at its highest. If you do find a leak don't attempt to fix it until everything cools down. I've stripped hose clamps before and its not a pleasant experience when a hose pops off. Its messy and extremely dangerous. Check all your hose clamps/connections, make sure they are tight. And check the hose connection to your coolant bottle, look for cracks, pinholes etc. in the bottle.

Thats about all there is to it! An enclosed system that operates by the expansion and contraction of coolant.