after about ten minutes of driving the coolant hoses get really tight but temp stays around 180 and overflow bottle doesnt fill. I tried a few different radiator caps. If the cap is not turned all the way to the right but still on enough not to leak, temp still stays around 180 but hoses dont get tight. Is there a difference between the plastic piece that you screw the radiator cap to. My car is a mix of s4 and s5 parts and I remember swapping out the plastic piece because one had a plastic nozzle for an overflow hose and one didnt. Are series four radiator caps the same as series 5? or does one sit lower in the neck.
Coolant seals are pretty much ruled out because car doesnt smoke, I did the bubble test to see if seals were leaking the other way: a/f into coolant. 40 k on factory rebuild and no other problems

thanks in advance

 

On most S4 models there are two caps. One cap that is just a cap, and the other that is a radiator/overflow cap.

 

aight but if I put the just cap one on what will maintain 13lbs of pressure? the radiator im runnin doesnt have a spot for a cap

 

Yes.

 

Is the over flow hose free flowing?

 

They're supposed to. The cooling system pressure is ~13psi when hot.

 

hose isnt blocked because when cap is turned to the left a lil bit, coolant flows to the bottle. If tight hoses is normal I guess Im ok