Okay, as a poor grad student, I wanted to try and get an answer here before taking my 1990 240 automatic into the shop for a diagnostic.
For the past few months, I've noticed a slow coolant leak (lowering coolant levels in the reservoir) with an accompanying climb in engine temperatures. I've tried to make sure and keep the coolant levels up to avoid overheating, but I'm fighting a losing battle and I think the leak is starting to worsen. I've tried a few "stop leak" compound to no avail. The temperature gauge has, unfortunately, spiked VERY high a few times in the past few weeks, which I'm sure is terrible for the engine. However, on these occasions, even though the engine is noticeably hot after I turn the car off, nothing has exploded...yet. At this point, I'm wondering what I should do first. I feel confident that I could replace the water pump if there's a chance it's the site of the leak. I've also heard from a few people that it could potentially be a head gasket issue. However, if it were the head gasket, would the engine not have already "blown its top" under the high temperatures I've cruelly subjected it to these past few weeks?