Here is a picture the the venting bolt located(86 car),in the area where the upper rad hose connected to. Actually it is call the bleeder bolt. Use a 12mm wrench to crack it open ,you don't have to take it all the way off.
Make sure you tighten it back up once coolant start to come out fron there and top up the coolant in the coolant bottle.
Good Luck
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Bud
87 930 Black
86 951 Black
86 944 N/a Part Car
87 944S white
83 944 N/A Black
83 944 N/A White Auto