It could be leaking from the heater core spigot at the rear left side of the head, under the intake manifold. They tend to dissolve over the years if the coolant hasn't been replaced every few years or so. It could also be leaking at the head gasket near the rear of the block, although that's a pretty rare occurrence. I'd recommend a pressure tester. I bought the HF kit since it has a BMW adapter. Worked pretty well!