Yes, papers are finally turned in.

However, I wound up spending all day today flushing the cooling system on a friend's '84 300D. I was going to do mine right afterwards, but in the middle of doing my friend's car, the weather turned real bad real quick... At least I got my oil changed

As to the thermostat that I've currently got, it's stuck open. Unless I let the car sit idling with the a/c running for about 10 minutes (after driivng around), the temperature won't get up above 60°C (and it takes a good 15 minutes to get there from a cold start). I'm 99% sure that it's the thermostat and not the sending unit simply 'cause the heater stopped blowing as hot as it used to. In addition, the expansion cap doesn't feel as warm as it typically did in the past. Both of these events occured simultaneously, and occured very suddenly.

Actually, it was the realization that the thermostat was stuck open that prodded me into taking a close look at the cooling system and realizing that it's mainly got water in it (and I don't want to know how much rust)...

BTW, the thermostat by itself won't stop me from leaving; I can live with reduced heater output...as long as the engine isn't overheating. However, I'd still like to get it done...after the fiasco today, I'm likely going to leave a day late as it is...