I just got the engine back from the machine shop and installed. Started it and got it timed and just got it up to about 2k rpm when I noticed the lower radiator hose was being sucked in and the upper seemed to be pressurized more quickly than I expected. I would say maybe a minute after running (as fast as I could get the timing right dialed in) It seemed be warm fast so I shut it off. After a bit I tried again and the lower hose sucked in immediately again. I filled into coolant port on the intake manifold at the suggestion of the machine shop before filling the radiator to try to make sure there was no air in there. Any suggestions what I did wrong? Its new everything (water pump, thermostat etc.) It has an older "Be Cool" radiator.

Any advice is appreciated.

 

For starters get a spring in that lower hose to keep it from collapsing, probably should replace the hose AND put a spring in it. You are gonna have a tough time figuring out whether there is indeed a cooling problem or not until you have reliable circulation of coolant.

 

Years ago the lower hose had a coil spring in it to prevent the hose from collapsing, but nowdays the new hoses don't have a spring. I have heard it's because the hose walls are made stiffer so no spring is needed. Maybe your hose is weak? You can find springs online if you know the inside diameter of the hose.

 

Or you can get one of these temporarily.

 

I would leave the cap off until you see good flow through the tubes, I would think you capped it a little to soon. Your lower hose shouldn't collapse unless its in bad shape spring or not, sounds like a huge air lock to me. The ribbed hose Oldcutlass posted will help until you get the coolant flowing properly then capped.

Eric