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Old 03-09-2006, 12:21 AM   #1
Corellian Corvette
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No pressure in upper radiator hose. Is this normal?

Still working on getting my "new" 1974 Chevy pickup up to snuff and trying to 'undo' all the cusomizing by the previous owners

One thing I've noticed is that the upper radiator hose never gets any pressure. This seems unusual in that every single other vintage car I own gets a stiff upper radiator hose when the engine is at operating temp.

Now, the car doesn't overheat as verified by 2 gauges, IR thermometer and my hand.

P.O. says there is a 195 deg. thermostat which also is verified by the above gauges.

There is no coolant in the oil, no oil in the coolant, and no water leaks that I can see. I ran the engine with the rad cap off just to make sure the system is purged of air and there are no bubbles that might indicate a leaky head gasket. I'm told that the water pump is new.

Is it normal for these trucks not to pressurize the system? Again, the engine doesn't appear to be overheating but the lack of pressure has me worried.

Thanks!
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Old 03-09-2006, 12:24 AM   #2
cliffsta
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Re: No pressure in upper radiator hose. Is this normal?

Mine has pressure, I believe. I'm 99% sure.
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Old 03-09-2006, 02:39 AM   #3
MylilBowTie
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Re: No pressure in upper radiator hose. Is this normal?

Does the upper hose get hot like it flowing coolant?
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Old 03-09-2006, 03:17 AM   #4
ACES
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Re: No pressure in upper radiator hose. Is this normal?

My 1970 is not pressurized. I didn't think that 74's were pressurized, Do you have a picture of the radiator?

Even if it was pressurized at one time, it could have been swapped out to a nonpressurized system.
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Old 03-09-2006, 10:35 AM   #5
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Re: No pressure in upper radiator hose. Is this normal?

When the upper hose seems to never get pressure, then there is usually a problem. First, is the core full of water? Sometimes the air that is trapped, when you fill the readiator, is more than the makeup bottle can handle (if you have one). Second (you won't like this one) there may be a head gasket leak and it has pushed the water out and there is a lack of fluid in the radiator. This can be found by most radiator shops, most have a carbon monoxide tester to see if you are getting gases in your cooling system. By chance do you have the wrong radiator cap on the radiator? There are basically two kinds, one that vents and holds and then there is one that vents and allows water to be pulled back in from the overflow bottle. Last but not least, what pressure rating is the cap, it may be two low.
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Old 03-09-2006, 11:40 AM   #6
Corellian Corvette
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Re: No pressure in upper radiator hose. Is this normal?

OK all good questions.

1. Rad is full of fluid.
2. Yes upper hose gets hot and coolant is flowing - I ran the car with the rad cap off, and I could see when the thermostat opened to let all the hot water flow in.
3. I checked for typical head gasket leak (bubbling in the water) but the water is still. That doesn't rule out a head gasked leak as you say.
4. How do I tell a pressurized vs. non pressurized system? There is an overflow bottle, and the rad cap appears to be a standard AC Delco type unit from the 60's/70's.
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Old 03-09-2006, 12:19 PM   #7
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Re: No pressure in upper radiator hose. Is this normal?

Just for safety's sake---Get a new rad cap..15 psi.
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Old 03-09-2006, 04:32 PM   #8
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Re: No pressure in upper radiator hose. Is this normal?

If you have the car running and can see the fluid cycling into the radiator from the hose I would thing your fine? The hose will be stiffer the newer it is, but you should be able to squeeze it when the engine is running wiht the cap on.
It not a high pressure system so-to-speak, but I would still be careful opening the cap when hot!!!
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