background:

92 B4C/1LE 5.0 (basically a Z28 TPI LB9)

previous owner changed the radiator cap to a 16lb stand unit with a vent on it, seen pictured below:


here is the issue.. my car was always running in the 230*+ range.. i changed the thermo to a 180* and also lowered the fans to come on at 195*.. even with the fans on.. still running in the 230+* range...

today when i came home, i turned the car off and poped the hood.. just for the hell of it i lifted the vent levor and heard and enormous rush of fluid enter the over flow tank

so i took it back out for another drive.. temp is lower... i come home, open the hood and find the upper radiator hose collapsed.. i pulled on vent.. more coolant rush into the overflow and the hose returns to normal shape.

now.. is this trapped air in my system? or is my water pump causing a cavitation somewhere? Is 16lbs the right cap to have? any ideas or thoughts welcome.

 

Maybe that cap is just not allowing the coolant to expand and go into the tank.
Those caps will go woosh when you lift the lever and it will fill the expansion tank. The lever is so you can release pressure before removing the cap.

When hot, the tank level should be high. After you shut down and it cools the tank level will drop. If its not doing that then I think the cap is not working.

 

Hey and how are you getting so hot un Utah, is there not any snow there???

 

ahahhaa.. yeah there WAS snow... about 3 weeks ago.. seems to keep missing Utah County and it hits Salt Lake county bad.

Anyway, the outside temp is like low 40's.. but this has been an issue since summer.. since its cold out, temps are about 200*.. i was referencing temps for summer since that was at its worst... so is 16lbs the correct lb for this car? i thought it might be 14lbs for some reason.. the collapsed hose has me scratching my head.

 

What I think is, when the motor cooled and the coolant contracted the cap did not let it take anything from the expansion tank and that is why the hose collapsed. Was the tank full when the hose was sucked in?
I think it the cap on the expansion tank was not venting it would have sucked that tank in or blew the cap off when the coolant rushed in.
Maybe also check for a lot of sediment in the tank. It could be getting drawn into the hose until you open the lever on the cap.

 

i am having the same issue and the radiator has the same 16 lb. lever cap...it runs about 230 but ive only owned the car a week so i am unsure what to do...previous owner replaced the thrmostat (notsure what temp) and the radiator fluid looks like crap ...can you PLEASE help me do i flush the system to fix? or do i simply get a new cap and if so what cap do i get?