Volvo S70 Made from 1998 to 2000, this sporty model replaced the 850 sedan and instantly became a hit.

coolant empty then take cap off an fills back up

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Old Jan 24, 2014 | 05:09 PM
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Default 2000 s70 coolant empty then take cap off an fills back up

The coolant tank is empty I take cap off to fill it and all the coolant comes back into the tank. This has happened 3 times now What can be causing this?
 

Last edited by d_scholz; Jan 24, 2014 at 05:48 PM.
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Old Jan 24, 2014 | 08:59 PM
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Is the engine hot when you remove the cap?
 
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Old Jan 25, 2014 | 05:24 AM
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Yes as soon as you hit the gas it sucks out shut the car off take the cap off n it all comes back in. It had a coolant leak that took me awhile to find. I bought new hose clamps an replaced them. Now this is happening. I have ran it with the cap off nothing strange happens
 
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Old Jan 25, 2014 | 08:19 AM
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First, you should not be taking the coolant cap off with the engine hot. Nothing good will come of that if the system is FULL. That is a great way to sustain a serious burn. The volume of the cooling system is fixed. When the coolant is heated it wants to expand. Water does not really compress, therefore something has to give and that is the pressure of the system. So... When the water is hot and the system is FULL and you take the cap off when the system is hot, when the cap gets loose enought you go immediately go to atmospheric pressure , the system is fixed temperature and the fluids volume immediately increases and it blows out of the top of the bottle. Hence the serious burns sustained. You can do a little studying of Boyle's Law you you wnat all the nitty griity detals.

When you fixed the coolant leak you must have lost some fluid in the process. How much depends on what leaked, how you repaired it and whether you took the coolant cap off in the process.

So..... you can either fill the system through the top hose and get all the air out (I don't recall that the radiator has a fill cap).... or you can keep adding fluid to the bottle everytime you run the engine and let it cool. Let it cool completely BEFORE you open the bottle.
 
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Old Jan 25, 2014 | 02:06 PM
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The car has a pressurized system and the reservoir cap should never be removed when the car is warm or hot.

Check the level first thing in the morning before you move the car and top it off then. If the proper thermostat is installed the system will burp well and you should only have to top it off once.
 
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