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Old 05-05-2007, 05:55 PM
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Radiator hose flattens

Any idea why my top radiator hose completely flattens when I start the car? (Chevy 350.) I need to open the radiator cap for it to unflatten. Replaced the hose yesterday. Still happens. Any insights welcome.


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Old 05-05-2007, 06:27 PM
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The water pump is sucking water out of the radiator. Since the thermostat is closed, its not letting water through and the hose collapses. Its not normal though. The thermostat is not supposed to seal in the housing. Its supposed to be "loose" letting water by. There is also an internal coolant bypass that may be somehow closed or clogged, but at any rate there shouldn't be that much suction on the top hose at start up.
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Old 05-05-2007, 06:57 PM
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Some applications use a wound wire spring inside the hose to keep it from collapsing. I know there is one in the upper hose on my 454.
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Old 05-05-2007, 07:01 PM
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Do you think replacing the thermostat is needed?
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Old 05-05-2007, 08:09 PM
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re: radiator hose flattens

Sounds like you might have big air bubble trapped in there. Disconnect your upper hose and refill the system up to that point, let it sit a few minutes to work the air out. Rehook the hose and try again.
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Old 05-05-2007, 08:22 PM
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my grandparents had a ford back in the 50's like that before they bought their 1952 dodge hardtop convertible (later sold for like $900).. he put a big spring in it.. but later traded the car back in because he said that all fords were built to run hot. about a month later there was a recall on them because they were running hot b/c of hose collapsing...
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Old 05-05-2007, 08:43 PM
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Doc here,

With summer coming up, you'd be well advised to Drain and flush the system, Replace the thermostat with a New Fail~Safe, and if it doesn't have bypass holes in it, drill an 1/8 in hole in it for closed bypass, Replace the upper and lower hoses with new Internal Spring reinforced hoses, inspect and if needed replace the heater hoses, Refill the Radiator with the proper mix for your climate with coolant.

Burp the system,

To do that, Raise the front of the car slightly, or park it on an uphill driveway,Fill the radiator to the top, put a LESS than pressure cap on it, (I.E. if the system is 15 lbs, put a 10 lbs on it) FILL and KEEP FILLED the recovery system, Do not let it run dry while burping!

Start the car, let it warm, and inspect for leaks, If none, let it run but Keep an eye on the temp gauge. Do Not let it overheat..During this time any air in the system will be expelled into the recovery can, and withdraw coolant back into the system to replace the trapped air..This is why you need to keep the recovery can full while doing this.

It SOUNDS and LOOKS terrible during this proceedure..BUT it is normal..don't worry about it..it will thump and gurgle and push coolant overboard but it's correct..Do this until it stops expelling air..(no more noise/Gurgles) then shut it down, let it cool, and replace with the proper pressure cap.

Summer is Here..

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