I noticed both aux fans running full tilt the other day when I got home. I glanced at the temp needle and saw that it was only a little ways from the red (it was only 85F outside). So I kept an eye on it for the rest of the week until I could take a look this weekend. It continued to run very hot when stopped in traffic, but not all the way into the red. Well, I was thinking water pump replacement, but after a search, it sounded more like the thermostat. So, I took it out and checked it in boiling water. It barely opened when hot. I ordered the thermostat and o-ring from fastlane and stuck the thermostat housing back on without the thermostat. This should keep it cool until I get the part in right?? Well...its better, but when stopped in traffic it's still getting awfully hot. Why would this be? I would think that without a thermostat, the car should almost run too cool. Am I missing something? The fluid doesn't look contaminated. Am I still going to need a water pump? Does running too hot do something to the antifreeze and now it needs replacing (it was changed a year ago)?

Ken Fuller
1990 300E
145K Miles