[Beemernut]

96 m44 318ti. Replaced the expansion tank with a Behr unit. It immediately leaked at the seal, so embarking on a 500 mile trip, I had to add a quart of water every 100 miles. Also discovered a crack in the radiator. I work at an Auto Value so I ordered a Parts Master (Spectra) radiator since I could get it next day. That immediately leaked at the expansion tank seal as well. So I've only been driving the car around town which usually doesn't exceed 10 miles one way.

Saturday my family came to visit and my sister wanted to learn to drive stick. Halfway through the lesson I saw the temp needle in the middle of the red zone and immediately shut the car off. The water (not coolant since I haven't re-replaced the radiator) level was fine but the coolant was boiling. Both hoses to the radiator were hot. No sign of coolant in the oil, no white smoke that I'm aware of, no sign of oil in coolant. Could I have a stuck thermostat? Water pump? I'm beginning to fear a head gasket anyway.