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scksupe
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should my coolant overflow tank be at the top even though i only filled it up to the fill line. after driving it it then mysteriosly fills up to the top, is this normal.
 

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brs86supra said:
should my coolant overflow tank be at the top even though i only filled it up to the fill line. after driving it it then mysteriosly fills up to the top, is this normal.
Im assuming when you filled it that the car was cold. If so are you sure you didnt fill it up to the hot line on the overflow tank?
 

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scksupe
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Discussion Starter #3
i filled it up after filling up my radiator while the car was warm adn i filled it to the full line rigt above the low line
 

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I experienced this exactly. Some gases in the coolant are forcing some coolant out of the system and into the overflow bottle. If the car is hot and idling, you might see the gases bubbling into the bottle - it looks like the coolant in the bottle is "boiling".

What's actually happening is that, during the engine's compression strokes, a bit of ignited gasoline and air mixture is escaping from the combustion chamber, and into the engine's water jacket. It's escaping through a tiny channel in a failing head gasket.

Many members have seen this, and it's so common that it's now an acronym, a BHG - or Blown Head Gasket.

Do a search, you'll find the way to diagnose this definitively.
 

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If your overflow bottle level rises a bit after driving your car, that is the sign of a properly functioning cooling system. If, after allowing your engine to cool down, this excess fluid isn't drawn back into the radiator, this is the sign of a problem, and isn't normal.

From your brief description, it sounds as though your overflow bottle may be filling successively higher each time you drive your car? (Meaning the excess is never drawn back into the radiator). Time to troubleshoot.

Causes? Could be a BHG, but check the easy/cheap stuff first. Radiator cap relieving too soon?

I just went through this troubleshooting process. My 90T with 117k on it failed the Block Test, which indicates combustion gases in the cooling system. This is what is pushing my coolant into the overflow bottle. Could be yours too, but troubleshoot it first.

See here: http://www.supraforums.com/forum/showthread.php?t=353868

Let us know how you make out.
 
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