Hey guys I got a 91 integra with the B16A swap. A long story short the car was running fine. Then I took and replaced the thermostat and both radiator hoses. Now after I drive the car the upper hose will be flat. I bled the cooling system and even put the old thermostat back in and it does the same ****** thing. It was totally fine before I did any of this. Any ideas??

 

Check the skinny hose between rad cap and reservoir. Is it blocked or kinked?

 

Make sure the upper hose is not twisted from installing them to their outlets.

The engine temps are still normal, coolant levels are fine, but your upper hose just is collapsing, correct?

While bleeding your coolant system, the upper hose did not collapse at all?

 

Where did you get the rad hoses from? 94

 

The radiator cap has a valve in the center to pull antifreeze into the system after the engine is off a while. Some negative pressure occurs as the system cools down. Sometimes just disturbing the system can dislodge sludge and cause this.
If this part of the cap is not working or the overflow tube is blocked the hose will collapse.

This is when the engine has been shutoff correct? Because if this is warmed up while running you have some serious issues.

 

My guess is rad cap not sucking the fluid back in. The cap doesn't need anything special to do this as it works under vacuum/pressure.

 

The upper is Day Co and lower is Gates brand. The overflow tank is blocked off by the radiator cap. It is corroded in that little outlet that goes to the hose for the resovoir. My buddy seems to think the radiator might be corroded as well?? The upper collapses after I bleed the sytem and let it run a half hour then put the cap on then. Take it for 5 minute drive. I park and open the hood and the ******* upper hose is flat as a pancake.

 

Your car doesn't overheat at all though?

If you take it for a drive, park it with the engine still running, and pop open the hood....is the hose still in normal form or is it flat and sucked in?

 

When the engine heats up, coolant will squeeze past the rad cap, through the skinny hose, and into the reservoir.

When the engine cools down, coolant will come out of the reservoir through the skinny hose, through the cap, and back into the rad again.

If the skinny hose is kinked, or there is some sort of obstruction somewhere along the hose or in its connections, coolant will not be able to come back to the rad, and it's possible for a vacuum to be formed that can pull the upper rad hose flat.

 

This statement is 100%. Its a simple problem, just ensure the path for this is clear, and that the negative pressure valve in the cap is able to function.

 

You need to get that coolant reservoir working. If its corroded try to clean off the corrosion but don't let it get into the coolant.

 

The overflow nipple is blocked off by the cap? Or are you saying that you have a cap over the overflow nipple? You are going to have pressure issues if the coolant cannot flow between the radiator and overflow bottle easily

 

The engine does not overheat at all. I let the sytem bleed out and engine to run for 45 minutes with the cap off then put the cap on and test drive it for 5 minutes then park it and the upper is flat as a ****** pancake. The radiator cap is brand new. The little nipple outlet for the resovoir Is totally clogged with white buildup. The hose is there leading to the resovoir but I removed the hose to inspect just to see that the thing is clogged.

 

unclog it

 

Then CLEAN IT OUT.

You haven't read a word of any of the advice I've given you, have you? I even gave a technical explanation of how the system works and why blockage could result in a flat hose.

I know: You're actually "Crazyhouse" posting under a new nym.

 

I'm going to unclog it this weekend. I work 60 hours a week and post when I can Idk what you mean by crazy house posting but you don't have to be an *** hole about it. Give me some god damn time pal.

 

Seriously though its something you can do in 5 minutes. Just pop the hose off and ream it with a paper clip or something. Probably want a new hose too.

 

"*******" is one word, not two.