on my 84 camaro 305 engine, my upper radiator hose i noticed is collapsing when i accelerate, i was adding antifreeze to the reservoir tonight and when i revved the engine from the accelerator cable i noticed the upper radiator hose (going to the thermostat) was sucking in. the hose is fairly new, as well as the thermostat which is a 195 deg. thermostat i beleive. the coolant system is was full with antifreeze, i did notice a coolant leak this morning coming from the bottom of the engine, but i beleive its coming from the heater core as when i replaced the hoses i think i pushed too hard on the hose..anyway what is causing the uppser hose to collapse? the coolant temp is below mid level it isnt running hot. but i am assuming the hose collapsing is restricting the coolant from freely flowqing through the engine. any help you's can give me is as always greatly appreciated


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1984 Chevy Camaro (305)

Make sure the reservoir cap has a good vent, and the small hose from the radiator isn't pinched.

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Don~ ZZ430DropTop (http://hometown.aol.com/zz430droptop67rs)
~~~~and~~~~
70 RS (http://hometown.aol.com/performancespecs)

the cap is brand new also. and the overflow to the reservoir seems to be working ok...what small hose? i dont think i have a small hose just the upper and lower hoses and otherwise there are the heater hoses.


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1984 Chevy Camaro (305)

The 3/8 hose from just below the radiator cap, that goes to the reservoir cap.


Also, if the radiator cap isn't correct, like for an open system, it will do that.



[This message has been edited by ZZ430DropTop67RS (edited 01-15-2003).]

the reservoir hose and cap are fine, i was told by the parts guy that a hose with a spring in side would solve this problem, but it dont sound right to me, could it be a blocked radiator? there seems to be adequate flow of liquid in the radiator, but im not sure.

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1984 Chevy Camaro (305)

the upper hose should never collapse- that is the one with positive pressure on it while the coolant flows. the lower is the one that gets sucked shut, and that's why most lowers have a spring in them. do you have the correct water pump? if you have a reverse rotaion water pump, and you are turning it the wrong way, the coolant will flow in the wrong direction, thus sucking on the upper hose and collapsing it. the car would probably overheat if this was the case, but not necessarily.

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1971 Nova(looks like 69 camaro from underneath!)
355sb, vortec heads, HOT cam,T-10 tranny, 3.70 gears 16X8" IROC wheels. 12" Corvette brakes on the way.
see dirty pics here of a car that gets driven http://community.webshots.com/user/novaderrik

i havent changed the water pump, and this seems to have just started happening, so thats why im wondering if its a clogged radiator?

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1984 Chevy Camaro (305)

I dissagree with Derrik The upper hose will tend to collapse due to the pull created through the lower hose through the radiator. It signifies that the t-stat is currently closed. When the tstat is open you will not feel this(or minimal). also when the system is under pressure this will not be present. I would not be too concerned unless you have other problems. If you do have a leak that may the problem. The systems need positive pressure to operate properly.

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67 prostreet BB Camaro The Combat Rat
80 z28 Camaro 355ci
71 BB SS Chevelle (clone)
2002 35th anniv SS Z28 conv.

You stated you replaced the T-stat, is it in right side up?

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My '68 Camaro (http://hometown.aol.com/Dougs68Camaro/index.html)
Doug G.
68 Camaro
406 ci.
13.5@102 W/ 2.73POSI.

it should be right side up, but they are cheap enough to replace, so i mnight just go out and buy a new one and flush the entire system and see what happens. the t-stat isnt too old only a few months, but it wouldnt surprise me if it is bad. ill see what happens

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1984 Chevy Camaro (305)

YOu guys better listen to ZZ430 Droptop here because he has nailed it on the head.

If you do not have adequate venting or do not have an open (two way) cap (that has backflow vent in the middle), or the tube from the reservoir to the cap is smashed/plugged or the reservoir top is plugged and not vented, the negative pressure present inside the system when the system is cold will pull the sides of the upper hose with some added RPMs.

Under normal circumstances the suction would pull in additional coolant from the overflow reservoir via the tube thru the vent in the cap to the radiator which equalizes the pressure difference (in this case the pressure being higher on the outside of the system). This is why the coolant reservoir would reduce toward the "cold" position on the reservoir tank as this happens.

Any hose is NOT supposed to collapse during normal operation....that just aids and abets fatigue of that hose.

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STEVE "Jack'Stands" JACK
Techical forum/links at Jack'Stands TechForums and Links (http://www.inccn.net/techforum.htm)

[This message has been edited by HOTRODSRJ (edited 01-16-2003).]

i think i forgot to mention the engine was NOT cold, it had been running for a while i was adding antifreese to the reservoir , i decided to make sure there was a good flow in the radiator so i revved the engine with the cap open to see, now i dont remember if the hose collapsed with the cap off, i dont think so though. im not overheating, when i start up in the morning and its been very cold i watch the temp guage, as i drive i watch the needle get to about 195-200 deg. and then the temp drops to about 140 when the thermostat opens. the reservoir hose is fine and i got a new radiator cap the one with the red presure release lever on it, i forget what pound cap it is but i bought it according to sepcs at the time which was in the end of summer.
sp im totally confused now.

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1984 Chevy Camaro (305)

Bantam, replace the upper hose. If you think it is original, or more than 4 years old, time for replacement.

Don't forget to change the lower and heater hoses as well.

Helluva a time to change hoses, 0-20*F, in NY?

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Everett "OBJECTS IN THE MIRROR APPEAR QUICKLY UPON RAPID DECELERATION"

the hose is only a few months old.
the lower hose is old i know that, but the upper hose, heater hoses and thermostat and rasitor cap are only a few months old, and yes its cold as hell here...lol, however i havent noticed this problem occurring anymore, so im assuming it was because the tstat was closed while the coolant heated up..

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1984 Chevy Camaro (305)