Collapsed upper radiator hose

George915 · Oct 9, 2024

So I just installed my new engine in my 1984 K10. New rebuilt 350 stroked to 383. Started engine on run stand 2 weeks ago to make sure everything ran fine. Finally started up engine for first time today in truck annd engine ran fine. Ran for 45 minutes in driveway hoping to burp any air bubbles out. Temp never got past 180 to open thermostat. Ran again this evening hoping to get air out again same thing temp stayed below 180. Shut engine down and when I came back out later upper radiator hose was collapsed. Removed cap and hose expanded. Everything is brand new on engine. Cold case radiator tuff stuff performance supercool water pump tuffstuff 180 degree high flow thermostat. Any help would be appreciated.

squaredeal91 · Oct 9, 2024

How is the radiator cap? New? Slightly newer used condition? Not likely but there are 2 different water pumps depending on if it's serpentine or v-belt. Both look the same but flow differently

ChuckN · Oct 9, 2024

I was gonna say, usually the lower hose has a spring in it to keep it from collapsing, so the fact that the upper is collapsing makes me wonder if it’s reverse flow? (Edit- meaning the water pump is reverse flow)

If it’s a Cold Case, you should have a new cap that came with it (mine did).

PrairieDrifter · Oct 9, 2024

Are the hoses new?

Turbo4whl · Oct 9, 2024

As stated, if the pressure cap is good, then there is still probably air in the cooling system. This is one of the reasons to drill a small hole in the thermostat, if it does not already have a vent. The vent insures that the cooling system is mostly full of coolant to start with.

George915 · Oct 10, 2024

Like I said everything is brand new down to the hose clamps I double checked the pump I have a v belt system it is not reverse flow unless it was packaged wrong. looked up the thermostat it stated it is designed to allow trapped air in the system to escape. Unless it is not operating correctly. And yes the radiator and cap are brand new

fast 99 · Oct 10, 2024

Assume this has a coolant recovery tank. Yes, a cap can cause it. However, if the overflow tank or hose is plugged that may also do it.

George915 · Oct 10, 2024

I took the overflow hose off and blew thru it and it was clear

fast 99 · Oct 10, 2024

George915 said:
I took the overflow hose off and blew thru it and it was clear

Try another cap.

George915 · Oct 10, 2024

Ok I will try a new cap tomorrow and report back. I am working all day today.

George915 · Oct 13, 2024

Well the cap was not the problem I don’t think I had enough coolant in the engine block. I pulled the thermostat to make sure it was working correctly and the coolant was sitting well below where the thermostat sat. When I was running the engine I turned the heater on to circulate some coolant could that have caused the coolant to drop so low ? Either way I filled up the engine block and ran the engine again keeping the cap off the radiator when the thermostat opened it burped out some coolant I topped the Radiator back off and put the cap on and everything is running fine now. No more radiator hose collapsing going on. Thanks for the help.

blackdot25 · Oct 14, 2024

George915 said:
So I just installed my new engine in my 1984 K10. New rebuilt 350 stroked to 383. Started engine on run stand 2 weeks ago to make sure everything ran fine. Finally started up engine for first time today in truck annd engine ran fine. Ran for 45 minutes in driveway hoping to burp any air bubbles out. Temp never got past 180 to open thermostat. Ran again this evening hoping to get air out again same thing temp stayed below 180. Shut engine down and when I came back out later upper radiator hose was collapsed. Removed cap and hose expanded. Everything is brand new on engine. Cold case radiator tuff stuff performance supercool water pump tuffstuff 180 degree high flow thermostat. Any help would be appreciated.

Does the rad have an overflow tank? The idea is for the cooling system to suck coolant back from the overflow tank as the system cools. If the tank is in place, I would suspect the rad cap is not functioning correctly.

JBswth · Oct 16, 2024

blackdot25 said:
Does the rad have an overflow tank? The idea is for the cooling system to suck coolant back from the overflow tank as the system cools. If the tank is in place, I would suspect the rad cap is not functioning correctly.

You need a new radiator cap. Also, see if you can buy hoses with a spring inside. That spring prevents collapsing.

J. B.

fast 99 · Oct 17, 2024

When filling an engine after repair good idea to leave thermostat housing off and fill until coolant is present. Then install stat before starting. Can do the same with a heater hose if located high on the engine. By the time a thermostat opens from steam engine is overheated.

ChuckN · Oct 17, 2024

fast 99 said:
When filling an engine after repair good idea to leave thermostat housing off and fill until coolant is present. Then install stat before starting. Can do the same with a heater hose if located high on the engine. By the time a thermostat opens from steam engine is overheated.

Like that idea. I think @Ricko1966 had recommended putting an aspirin or Tylenol tablet in the thermostat to prop it open for complete circulation before it dissolves and goes away. I haven’t tried it but sounds like a neat trick.

Collapsed upper radiator hose

George915

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