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vaccuume in cooling system for 75 Eldorado?

Started by Doug Spingelt, August 19, 2009, 05:52:33 PM

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Doug Spingelt

I have been noticing when I open the hood with the motor running that the upper radiator hose is sucked in as if there was a vaccume in the cooling system somewhere.  The radiator and lower hose are new as are the freeze plugs.  Any ideas?  I have never heard of this before.  (The coolant level is normaland is not overheating.)  Thank you!
Doug Spingelt

Otto Skorzeny

Does the hose collapse the instant the car is turned on ? Does it only collapse when it's hot?

Take the cap off  (when cold) and seal up the hole with the palm of your hand. Do you feel suction?

If there is a leak, then the water is going somewhere, right? Is the level dropping?

Is there water in the crankcase? Do you smell the sweet sugary smell of anti freeze in the exhaust? is it blowing steam - even a small amount?

The radiator hose should not collapse. You say it's new but maybe it's a piece of crap like most stuff sold today.
fward

Ask not what your country can do for you, but what you can do for YOURSELF

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Doug Spingelt

Ok, that is alot of questions, but I'll attempt to answer them 

It does collapse when you turn the car on, (A few seconds later)

When I took the cap off while running, it released the preassure/suction

I was able to add, maybe a cup or two of fluid is all, but I can't say if it was low, because I didn't refill it myself after the last work.  (Freeze plugs) There does not seem to be a leak. 

I smell no antifreeze and feel no steam anywhere... It seems remarkably tight. 

The top hose is old, but looks good, onlyn the lower is new.  could it really be just a tired lazy hose? 

Thanks for your assistance. 
Doug Spingelt

Otto Skorzeny

Can you feel suction on the palm of your hand if you use your hand in place of the cap?
fward

Ask not what your country can do for you, but what you can do for YOURSELF

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Mike Josephic CLC #3877

Did you replace the radiator cap when you did the other work?  The caps are designed to open and close -- hold and release pressure.  Just another thing to check.  Also, even though your top hose
"looks good" if it's over 10 years old it's likely bad -- the rubber hose may be collapsing inward due
to suction from the pump.  The rubber gets very soft and loses its elasticity and strength due
to heat and aging. A new hose would not do this.

I have a '73 Eldo and never had the top hose collapse as you describe.  However, when I do a cooling system "make-over" I replace all hoses, thermostat, rad cap, etc.

Mike
1955 Cadillac Eldorado
1973 Cadillac Eldorado
1995 Cadillac Seville
2004 Escalade
1997 GMC Suburban 4X4, 454 engine, 3/4 ton
custom built by Santa Fe in Evansville, IN
2011 Buick Lucerne CX
-------------------------------------
CLCMRC Museum Benefactor #38
Past: VP International Affiliates, Museum Board Director, President / Director Pittsburgh Region

Otto Skorzeny

I don't think the water pump would create suction at the top hose. The top hose receives the hot water from the engine block. Water is flowing through it into the radiator, not the other way around. If anything it should be pressurized.

There shouldn't be any vacuum effect in the cooling system. It's probably just a collapsing hose but if he can feel a suction effect with his palm in place of the cap then something is amiss.
fward

Ask not what your country can do for you, but what you can do for YOURSELF

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Sweede64

Does it happen when the engine is hot or cold? When its cold there can be a slight underpressue in the rad whitch turns i to owerpressure when hot, a bad hose tends to deform easyer tha a fresh one.
Thomas Karlström