Radiator empty, but coolant overflow tank full

[Connewm8]

I had my overflow tank replaced three days ago because the old one was cracked and leaking. Afterwards I filled both the overflow tank and radiator with coolant and it ran smoothly till today. Once again, the engine started overheating. After taking a look (when the engine was cold) I found that the coolant tank was still full but the radiator looked empty. Why would the radiator be empty? Could it be a problem with the pressure? I drive a '95 lesabre if that helps

 

[gnhbodyguy]

I would look at the possibility of air in the cooling system...

[ame]http://www.youtube.com/watch?v=Qgc6JQ2m_AM[/ame]

[ame]http://www.youtube.com/watch?v=zUpXgAJ1gjU[/ame]

 

[IMSITINGINYOURCHAIR]

I hate bleeding this system. It seems to take me forever to get it all out. I have devised a method that seems to help it along. From a full drain, Ii fill the radiator to the brim then close the lid. Then I open the bleeder screw and add coolant to the reservoir until it's about an inch from the lid, after I've done this, I take a shop vac and attach the hose to the blower side and block the vent part on the back of the tank with my finger and then apply pressure to the tank with the shop vac, forcing coolant into the block so as to help prime the pump. Once coolant starts out the bleeder screw, I start the motor and finish the process.


Pretty much, while you add coolant make sure the bleeder screw is open. All that air has to go somewhere as coolant comes in.

Things to remember, In my experience, it's a good idea to use water if you've made a major repair to the cooling system to check for leaks on first start up. that way if it breaks and dumps coolant out. it's just water and not antifreeze. Just remember that you will need to replace that with antifreeze once everything checks out ok.

 

[DonP]

Also make sure the reservoir is conencted to the radiator, the hose is unobstructed allowing flow, and the radiator cap is working.

 

[HotZ28]

Take a close look at the radiator plastic tanks on each end of the radiator. Usually, the tank fracture is located on the drivers side, near where the top hose is attached. You may have to remove the top mount to expose the area in question. If the tank is cracked, it will leak coolant when cooling down and when cool enough, the crack will draw vacuum through the crack instead of from the overflow tank.

 

[redmondjp]

Have you ever replaced your intake manifold gaskets?

You may have an internal leak that is making the coolant disappear.

 

[Enslow]

I second inspecting the radiator cap. I you are low on coolant but the expansion tank is full, I'd suspect the cap. You also need to find the leak. Get yourself a coolant pressure tester. You can pressurize the system (do cold) to 15 psi then look for leaks. If the pressure drops and you can't find a leak, I'd suspect the heater core, or LIM gaskets.

 

[imidazol97]

With the age of the car the radiator is a good suspect. My 98 had a crack at the top on the compound curves. When it leaked, the Dexcool with the stopleak powder from GM in it did not stick there. It only leaked when the system was under pressure. The coolant went into a trough under the radiator that occasionally would let some dribble out a drain hole at the middle. It looked like the AC had dripped, except it was under the wrong part of the car.

The plastic of the radiator did not show a trail. I found it by using a borrowed pressure tester with everything full up--OReilly's had it as a loaner. So do Autozone and some others. Test the car when overnight cold, otherwise the coolant inside the motor keeps cooling and dropping the pressure mimicking a leak.

Second problem I'd check is the underside of the radiator cap with a good cleaning with dish detegent and a toothbrush, an old one grin, to be sure the little disk that floats up to close off the water escaping to put the system under pressure is clean. When the car is warm, is the radiator hose hard when squeezed because the system is under pressure?

With the pressure tester I'd look at the water pump area and the heater connections and hoses everywhere for leaks.

To fill the system for checking, fill radiator until no more goes in after waiting a few minutes. Then start the car and run to warm it up with cap off to see if level drops and add more coolant as it's running. Then replace cap and warm up to temperature until lower radiator hose has warmed up. Then rev engine to 2500 for 10 seconds or so and idle, repeat 4 times. This should move trapped air from heater core into the engine. Then shut down and open the bleed screw on the thermostat housing to let out air trapped there.

Check system after cooled to be sure radiator is still full with coolant sucked back in from reservoir as it cooled and volume shrank.

 

[jman8579]

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