dan.757

Hey guys I have a 1999 Civic Si B16a2 all stock. When my car begins to cool after a drive both the lower and upper radiator hoses collapse. I've searched the forum but cant figure it out. At first the overflow hose was clogged so I cleared it from the radiator all the way to the bottom of the overflow tank when I got home they still collapsed so I slowly released the cap the air hissed and the hoses immediately went back to normal. Next, I replaced my cap (1.1bar/16psi) suspecting the valve was bad but the hoses are still collapsing. I don't think the cap is burping for the overflow because the level isn't changing and its obviously not allowing vacuum for the cool down. Any help is appreciated, thanks.

Former User

Rent the block tester kit from AutoZone to test for a blown head gasket.

dan.757

Man I hope that's not it, but thanks I will.

Former User

Good luck. You might first try bleeding the cooling system.

https://honda-tech.com/forums/showth...1#post39830585

dan.757

Yeah I was in the process but I got side tracked and forgot to turn the heat on, let the fan turn on, and rev the engine. But, I did let the thermostat open and squeezed the hoses with the cap off with no luck.

dan.757

I did forget to mention they ONLY collapse when the car is cooling down not while driving or just stopped but a few minutes later.

Former User

Do the full bleed procedure and then go from there.

dan.757

I will, thanks.

cvcrcr99

Follow RonJ, but you can always look into the cap. I am sure he will get to that sooner or later. Many times, the cap isn't letting fluid back into the system during cool down and creating vacuum in the system.

Former User

dan.757

Sorry to revive an old thread, but just wanted to come back with an answer for anybody who is having the same problem. I fixed the problem by turning the new cap the opposite way so the words would be upside down if you were facing the engine bay and tried not to overtighten, test drove the car 3 times and it somehow fixed itself. I also went ahead and did a coolant flush because the coolant that was in the car (just got the car not that long ago) had drop-out from an over concentration of coolant to water creating a "green goo" substance which would clog the overflow hose sometimes. The car is running great and even a few degree cooler, thanks for everyone's help.