how does a radiator able to both fill into and suck out coolant from the reservoir via only one tube?

Question

Wouldn't the radiator cap prevent fluid coming from the reservoir to the radiator?

Answer 1

The reservoir is only for overflow. When the system gets very hot the fluid expands and some of it will be "squeezed" out into that reservoir. When it cools off again it will draw that fluid back into the radiator.
It's the same as you sucking water up through a straw and then blowing it back out again.

Answer 2

Arjay, I'm going to throw a small curve at you. All the above answers are correct. Ford systems work differently than most others.

As you know most radiators have a cap on the top of one of the radiator end tanks except Fords. They have a pressurized coolant recovery tank. The normal 16 lb. radiator cap is on the top of this tank. The pressurized tank is clear plastic. When water / antifreeze gets hot it expands. The pressure cap relieves coolant pressure if It exceeds 16 lbs. The coolant under pressure is pushed to this tank. As the system cools, a relief valve in the top of the cap releases pressure and allows coolant to be drawn back into the cooling system.

The reason cooling systems are pressurized is coolant will not boil at the usual 212 degrees atmospheric boiling point. When using a 16 lb. pressure cap the coolant will not boil till it reaches a temperature over 260 degrees F. It's a safety factor because the added heat loads placed upon the motor during hot weather with the air conditioner on carrying weight (passengers) and pulling loads up hills.

Answer 3

No, the cap doesn't prevent the fluid from exchanging back and forth.

Your radiator cap has two gaskets. The top one is solid mounted, the bottom one is spring loaded.

It's the bottom gasket that serves as a pressure relief valve, and the top one that prevents the coolant from escaping, instead it is routed through the tube into the overflow bottle.

When the engine cools, the spring loaded gasket doesn't effectively prevent coolant from returning from the bottle. As the coolant cools it becomes smaller in size and the smaller volume of liquid sucks the overflowed liquid back into the radiator/cooling system.

Because 67% of all mechanical failures involve the pressurized liquid cooling system, I simply removed the bottom gasket from my cap. To do this, I had to get a four-row ultra-cool radiator (desert cooler) because for every additional pound of pressure in your system, the temperature in your system can be 4 degrees higher before it boils over.

So my car will boil over more easily because I have zero pressure, but my hoses never burst and I almost never get water leaks.

I do run about 90% coolant, and I use the Mercedes Benz brand coolant (which is more than twice as expensive), so I can go a bit above 212 degrees, but not much more.
.

Answer 4

The design of the radiator cap allows the water to escape when the pressure in the radiator exceeds a set pressure. When the engine cools there is a vacuum in the radiator that sucks coolant from the overflow bottle back into the radiator. The radiator cap has a check valve in it to allow this to happen...See: http://auto.howstuffworks.com/cooling-system7.htm

Answer 5

Run the automobile for a at the same time as, rev the engine, get below it. seem for leaks, hear for hissing and poping around your hoses and coolant lines and hoses. you are able to try those radiator end leak, yet i might advise against it till you're optimistic there's a leak. Then verify your radiator cap (spring or seal on the cap may well be wiped out. low-fee restoration) verify your reservoir tube maximum appropriate to you radiator. verify your gravity (water to antifreeze 50/50) in case you have plenty extra water in mixture, that's evaporating straight away. Do a rigidity attempt to be sure you have not got a head gasket leak. verify your coolant shade, if oil is latest, you'll be staring at maintenance (you are able to try employing head gasket sealers, like Blue devil, or Bars Head Gasket restoration... yet that often only buys you slightly time)... Your problem is in there someplace. wish it is not costly. good success.

Answer 6

When the liquid gets hot, pressure forces excess out to the tank. As liquid cools, a vacuum forms in the cooling system to draw reservoir liquid back into radiator.

Answer 7

no.the radiator cap opens and shuts as you drive.when the engine gets hot,the cap opens and spills over into the reservoir,and when it cools down, then vaccum pulls it back into the radiator.

Answer 8

they call it pressure