Cooling system not working

[RickOTR]

I just installed a new Radiator and Cap in my Explorer and now when the engine is cold the upper radiator hose is all sucked in. Checked the coolant reservoir and hose but there are no leaks or blockages. Any ideas?

 

[Thuggsy]

faulty cap

 

[RickOTR]

UPDATE: After installing a new Motorcraft radiator cap I was still having the same problem. I than began a visual inspection of the whole radiator. I soon found that there is no hole in the radiator nipple that attaches the line to the recovery tank. I checked four other aftermarket radiators and none of them have the hole either. Is it safe to drill a hole through the nipple? There's not a lot of margin for error if doing so. Next, would it hurt the cooling system if I leave it this way for a while?

 

[Thuggsy]

thats nuts!
well, at least i wasnt exactly wrong.

do not drive it like that, there is no pressure relief, youll blow something out.

id return the rad, no knowing what else is wrong with it.

 

[RickOTR]

Update 2: Took a soldering iron and stuck it into the radiator nipple and melted a new hole, and all is well again.