Technical Collapsing Upper Radiator Hose

Need an education on why an upper hose would collapse

• basic SBC
  
• just added catch can - makes me think this is prob but dont understand why
  
• catch can has rad hose and overflow line
  
• cooling system works perfect holds temp no issues
  
• cooling off and upper hose collapses

 

Is your radiator cap of the type that have a return facility? There should be a round, spring loaded flap in the centre. You can gently pull it away and it should spring shut. It allows expelled coolant to be drawn back in when the system cools and contracts. You also need the hose in the can to be under the fluid so it can be drawn back in ( its a recovery tank, not a catch can). Sounds like you have the wrong cap, fluid is expelled but in cooling there's no way to pull coolant back so the system collapses the weakest point.

Chris

 

Thank you Chris, Ill check the cap style

 

Catch can also needs to be vented.

 

The overflow in the recovery tank is open to the atmosphere...in most cases

 

I should have said "be able to" vent.

 

If the upper hose is collapsing it has to be the cap not letting air or coolant back into the radiator as it cools.

 

yes, to clarify the recovery tank has two lines on bottom, one coming in from radiator cap and is flush to bottom of tank, and an vent/overflow line that extends into tank about 5in, attached to rubber line down to bottom of frame.

Will take pick of cap once cooled off.

 

Recovery can / tank sounds right. Just seen the pics. The convoluted hose is more stretchy than molded hose. Is there a spring in there? There is in mine. Also, I see a convoluted bottom hose. There has to be a spring in there as otherwise its liable to collapse under suction from the waterpump.

Cooled yet?

Chris

 

My Dad always referred to those as Puke Boxes! LOL

 

I have that same catch can, works like a charm. Your radiator cap is the wrong type or the valve for coolant return is jammed.

 

I think it actually has the vacuum valve, but might be gummed up or not working. when i pulled it away from gasket there is some crud in there.
makes sense, reason im even messing with this is I was doing a cooling system flush.
will try and clean out cap, and then find a new cap if necessary.

 

That's the correct type of cap!
Stumped now!

Chris

 

Where the hose from the rad loops under the recovery tank, is the bend nice and wide? Could it be kinked or tight enough to close up under vacuum?

 

Had the same issue on my daughter DD, OT but SBC-not LS, etc. I think it was @31Vicky with a hemi who steered me in the right direction.
It did solve it, but search thread topics from 4/6 years back started by me.
If I could remember what I did, I’d tell ya!

 

That was helpful.

 

When the top hose is collapsed remove the overflow pipe from the radiator neck. If air is sucked into the radiator and the top hose returns to normal yoir problem is in the catch tank or it’s pipe work. If nothing happens and the top hose stays collapsed the problem is to do with the rad cap.

 

when I cracked cap open it released the vacuum, will clean cap or buy new one see what it does.
also was an ebay radiator so would not be totally shocked if cap was a throw away.
will also double check recovery tank lines.

 

7 Dollar NAPA cap resolved it, letting fluid move in and out of recovery tank.

 

It wouldn’t hurt to put a fairly “strong spring” inside of top radiator hose in question to make sure it doesn’t collapse because of some strange thing happening in the water supply system!!!