Upper Radiator Hose Collapsed ?

[Greekman]

Upper Radiator Hose Colapsed ?

Today after driving my '79 for its monthly startup during the winter months, I noticed that my upper radiator hose was colapsed! Yes, flat as a pancake?

What has happened? Is this normal? Should I be concerned?

Maybe a stuck thermostat? I did have the heater on for about 30 minutes.

Please help as I have never seen or heard of this happening before.

Thanks,


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[Pappy]

Did you check for low coolant level?Might be time for a replacement, I would do the lower hose also,did the hose feel spongy? if so replace.if you haven't replaced thermostat in awhile I would do this also.

 

[Greekman]

Pappy, engine was too hot to remove radiator cap that I thought if removed would also vent the system and return the upper hose to its normal state. I did smell some coolant, but I had noticed before a small pin hole in the radiator and had added some radiator stop leak.

Haven't replaced the upper or lower hoses as dealershiip said looked fine when they replaced all the heater hoses last Fall.

I replaced the Thermostat last summer when car was running a bit hotter than normal.

Once the motor cools down I will look again at the coolant levels in the radiator and overflow tank.

I have had the car for less than one year so still looking everthing over mechanically.

Thanks for you thoughts and maybe still someone out there has seen this before.




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[Vanity Plate Bob]

Years ago a hose would weaken and collapse.
Then some had a spiraled wire in them. I'm sure they are better material now but if its orig, that's a long time.
May be a good idea to replace it.

 

[78SilvAnniv]

I'd replace it.

If it has collapsed once, it will again, with less effort.
Heidi

 

[Jack]

I'd take a look at the cap, overflow hose & overflow tank. Maybe it got hot enough to puke a bit into the OF tank, but maybe the OF hose has a kink in it or there's goop in the OF tank that prevents the system from sucking it back into the rad ... as it cools it makes negative pressure ... collapsing upper hose?

Bottom rad hoses are most prone to collapse ... 'cause the wp sucks from that hose ... bottom hose is the one that needs a wire core/spiral. A chevy can suck even a NEW lower hose shut if it don't have some kinda support in it
JACK:gap

 

[gary b.]

Today after driving my '79 for its monthly startup during the winter months, I noticed that my upper radiator hose was colapsed! Yes, flat as a pancake?

The exact same thing happend to my "78"
Mine still had the original radiator cap, so i replaced it & now
the upper hose do'es not colapse anymore!

Get a new cap with the correct pressure rating, and all
will be well!

 

[Stallion]

The exact same thing happend to my "78"
Mine still had the original radiator cap, so i replaced it & now
the upper hose do'es not colapse anymore!

Get a new cap with the correct pressure rating, and all
will be well!

If by changing the cap (which works off of pressure and has a spring on it?) do you think that it worked because the spring in the cap for the pressure was shot and done?

 

[Big "O"]

It's possible that the radiator, when filled last year, was filled up but not enough to fill the engine compartment and heater. If this happened and let's say your coolant level was low in the radiator, the water pump would be circulating air instead of coolant through your engine causing the upper return hose to collapse or get squeezed out. The fix, turn on engine, turn on the heater, remove the cap, observe level after engine warms, add coolant, replace the cap and feel the upper radiator hose, feeling for pressure (coolant) of the coolant traveling back into the radiator. If you feel no pressure at the hose and the hose collapse again, your thermstat is definately stuck.

 

[Greekman]

Replacement Hose Ordered

First of all thanks to all of you who responded and helped me out with this unusual situatiion.

Once engine cooled enough to open the radiator cap, I noticed the following:

The radiator was full.
The overflow tank was at normal max level.
The upper radiator still after venting the system would not go back to its normal shape. After a closer inspection of the upper radiator hose it did feel somewhat spongy and weak.

I did the following:
Ordered from Chevrolet a new upper radiator hose.
(Was going to replace the radiator cap, but Chevrolet has replaced the original stainless steel cap with a new black plastic type so I decided to give mine a try first).

I'll let everyone know if after the installation of the new hose if I still encounter the flatting of the upper hose.



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[Vanity Plate Bob]

I am almost certain there is a gauge unit that can ck press of a cap. The gauge is attached and a hand pump supplies pressure.
It is the size of an oversized aniti freeze tester. This is performed with the cap removed from the radiator.
Ck a radiator shop, repair shop, dealer etc.

 

[Greekman]

Yes, I have a Zant Tester as you described and will test the pressure on the cap before completing the upper radiator hose installation.

A good idea. I can also pressure test the whole cooling system while I'm at it.

Thanks,


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[resto75]

If it was me I would spend the 50 bucks and replace all the hoses, rad cap,therm, coolant etc. Why take the chance of something that might be 20+ years old and can leave you stranded on the side of the road at night.

Those are all inexpensive items which should be replaced BEFORE they go bad, not after. You have just gotten your first warning with the top hose.

Roy

 

[Greekman]

This hose just slipped by me.

Roy, thanks for your reply.....

I have had the car less than a year and have had to deal with the more immediate troubles like leaky brake calibers and steering linkage.

I did have the car into the Chevy dealer and they replaced all the hoses they thought looked like they should be replaced. They replaced all the hoses except the upper and lower radiator hoses.

It would sure be nice if we could predict ahead of time what items on a 24 year old car had been and or will need replacing before it fails.

I do intend to have this car Flight Judged and do not want to replace items on an original car just because its old. The car is not a daily or even weekly driver and when its on the road it is often with other old Corvettes.

Thanks,



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[KOPBET]

Re: Replacement Hose Ordered

The upper radiator still after venting the system would not go back to its normal shape. After a closer inspection of the upper radiator hose it did feel somewhat spongy and weak
.

Jack is right IMHO.

This is a bad hose regardless of anything else going on in your engine. Replace it and the lower as well if it is as old. Keep the spring from the old lower hose unless the new one has one in it!

The upper hose should be pressurized by the water pump and should not collapse from suction. If the stat doesn't open then there is no place for the pump to push the water, hence no suction on the lower hose. Therefore I doubt this is the problem.

The hose material just gets soft and weak over time and this one just does not have the structural strength to support itself.

 

[Vette/Berlina-coupe]

-an older unsupported type upper/radiator-hose can collapse entirely when the engine cools, -owing to cooling and contraction of the H2O-molecules (thus the shrunken water-volume creates a neg.press to collapse the upper-hose); -alas no big deal at all, as you will note it automatically recovers to normal shape as the engine water warms-up. Or, your Water-recovery system may simply be empty of water, or you may need a proper Radiator-cap with a neg.pressure relief-valve which has an integral smaller R.cap-valve that opens so recovered-water will be sucked back in as engine cools, --thereby preventing unsightly hose-collapse (the problem has nothing to do with your engine's thermostat which closes when engine cools)! However, if this bothers you (ie: -you toss'n turn, can't hardly sleep at night fretting about it) and you never want to experience such horrid anguish and unsightlyness ever again, --simply install an American-made "marine-hose" (boats have to have the safety factor) of same size, --it will outlast you!!! ~Bob vH
:dance

 

[JohnZ]

Upper radiator hoses have NEVER been internally supported/reinforced; they don't need it, as they're always under pressure when the engine's running and the thermostat is working properly - only the lower hose has a spring in it, as it's under constant suction from the water pump inlet. If the upper hose is collapsing, the thermostat is stuck shut, and the suction from the water pump inlet and back through the radiator is collapsing it. When this occurs, only a small amount of coolant circulates, through the bypass hole in one side of the water pump.

 

[Greekman]

Thanks JohnZ....

When I removed the upper hose I looked down into the thermostat housing to see that the thermostat is in the CLOSED position. Now that would be correct I believe since the engine is COLD or should it be OPEN since the last time it worked the engine was HOT?

Anyways I think it would be a wise decision to also replace the thermostat while working in the area with the hose even though the thermostat is less than one year old.

Are Geniune Chevrolet Parts like a thermostat have a one year warranty? Maybe I should remove it first and take it back to Chevy when I buy or ask for another one?

Thanks guys and gals for all your thoughts.

When I posted this message I didn't think it would generate so much interest, but I guess this has or can happen to everyone and there are alot of possible sources for the problem.


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[Vanity Plate Bob]

As engine temp cools the stat closes. When it is closed the water can not flow so it stays in the area of the engine that gets hot quicker. A heater will not work with an open themostat or with no thermostat. The water circulates too fast and will not get hot.
I'm not sure of the technical reason for haveing hot water other than for the heater.
Also water will get hotter before it boils under pressure.

 

[Greekman]

The Concenus..

From what I have read here..the concenus is that my thermostat has possibly stuck CLOSED and caused the coolant to reverse in the system and with a soft and weak upper radiator hose to collaspe.

This makes sense to me.

The fix:

New Upper Radiator Hose ordered
New Thermostat to be replaced.


Thanks to all,



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