1997 BMW Z3 Roadster 4 Cyl 1.90L
Why is coolant leaking from Z3 BMW?
A few months ago my dad helped me replace the radiator in my 1997 Z3 BMW because it was leaking along the junction between the plastic and metal parts. I haven't driven the car much at all since then, but today I drove about 4 miles and the engine started to overheat. I stopped to open the hood and noticed that coolant seemed to be leaking out of the closed reservoir cap. I could hear sizzling noises coming from the cap. When I got home, I noticed that almost all of the coolant was gone from the reservoir (it was filled about halfway when I first stopped). Could this be a water pump issue? Alternatively, I have the reservoir cap from the previous radiator on the new radiator because the new one did not come with one. Could this be an issue with the cap not sealing completely? Do you have advice on where else the leak could be coming from and how to solve this issue?
Possible leak points include; hoses, the radiator, heater core, water pump, thermostat housing, head gasket, freeze plugs, automatic transmission oil cooler, cylinder head(s) and block.