Just noticed this. My upper radiator hose and the smaller hose that runs horizontally across the engine (see pic, the pic is sideways for some reason) are both collapsed, totally flat. I didn't poke around to inspect any other hoses, just noticed these two. I replaced the water pump last month because it was leaking, but the car doesn't overheat. It does seem to take a while to warm up, 10+ minutes or so at least of driving before the needle even moves on the temp gauge, but when fully warmed up the needle goes to halfway and never any higher. So I don't seem to have any other symptoms or issues, just these flat hoses. Any idea what causes this? And is it fine to ignore or should I replace them? Thanks!

 

I guess (and hope) that the picture was taken with a cold engine and that the hoses become round with the engine operating.

The fault is not with the hoses, there is for some reason a partial vacuum in the cooling system. Try releasing the filler cap again with a cold engine and verify the coolant level.

 

I think you've got a thermostat problem, or at very least in need of bleeding the cooling system. Have you noticed the cabin heater not working normally?

 

Upon further inspection, every single coolant hose is flat, including the one that connects to the reserve bottle. With the engine cold, I removed the cap on the coolant bottle, but nothing changed. The hoses remained flat and the coolant level did not go down. The hoses appear to remain flat whether the engine is cold or hot, yet no signs of overheating and the needle on the temp gauge stays at exactly half way. I guess I will replace the thermostat.

 

It is not the thermostat. I have had lots of thermostats fail and they never draw the vacuum that your system shows. You almost certainly have a problem with your cooling system cap. It should release the vacuum when the engine cools.

Try this experiment; remove the cooing system cap when the engine is hot and the hoses are their normal shape. In the cold weather there should not be much pressure in the system but be careful anyway. Let the engine cool down with the cap off. The hoses should maintain their normal round shape when the engine is cold.

I looked at my cap and could not see the vacuum release valve and they apparently cannot be disassembled. They are not made like they were in the old days! Somewhere in the cooling system there is a vacuum release valve and that is your problem. It is probably in the cap.

Another (unlikely) possibility is that there is some leak that connects your cooling system to the intake manifold, some gasket or seal somewhere. The vacuum from the intake manifold would be getting into your coolant system. A symptom of this would be you would loose coolant and it may come out the exhaust.

Pete.

 

Searched internet for this problem and couple of YouTube videos came up. Here's one:

 

That video shows the type of radiator cap that I remember. The smaller silver disk on the bottom of the cap is the vacuum release. The X-Type cap is quite different. The valves are inside the housing and can't be examined so easily. Perhaps the only thing that can be done is to replace the cap.

Pete.

 

saw this in the trade .perfectly operating cooling system, collapsed hoses,reason,after a lot of head scratching, hoses collapsed due to old age, inner walls breaking away from outer wall, hope this helps