I just purchased a '92 Montero SR with 168k on the clock. The truck is solid, passed emissions with no problem and overall seemed healthy. The truck was slow to warm up, so I decided to replace the thermostat today. This apparently set off some chain of events that I cannot explain.

As soon as I refilled the coolant and started the engine, I had a smoke/steam combo coming out of the exhaust. There was a puddle of water forming below the exhaust tip. I also noted a reduction in oil pressure. The smoke/steam was pretty bad. I also noted the presence of coolant in the valleys near the fuel injectors on the passenger side. It was not coming from the thermostat housing.

I drove the car around and the smoke/steam seems to have subsided, but the coolant leak persists. I am showing very little oil pressure at idle. Oil level is good and doesn't look milky yet.

Any ideas of what is going on?