Well, as you put it, "where to start". By your description, it sounds like you have a head gasket out or possibly a cracked head. These little motors don't take being overheated very well. If cylinder compresson is leaking into the cooling system it creates an air pocket in the coolant and decreases the coolant's ability to dissipate the heat from the engine causing overheating. Also, the exhaust pressure buil;ding up in the cooling system pushes the coolant out of the system. Two things you need to do: 1. Have the cooling system tested for the presence of exhaust gases. You can get a test kit from any good parts store and do it yourself, or have it done at a shop. 2. Do a compression test on all 4 cylinders. This should tell you what wrong with your #2 cylinder.
The control that turns on your cooling fan needs to be imersed in coolant to work efficiently. If you have an air pocket around the sensor, it will delay or stop the cooling fan from running.
Other things to check: The color of your engine oil. If the oil looks like a "chocolate malt", that's indicitive of coolant leaking into the cylinder(s). If this is the case, it will destroy the engine bearings. Hope this helps. But, from what you have said, it doesn't sound good.
Wednesday, March 4th, 2009 AT 6:15 PM