I once had a car that would overheat whenever it was put under heavy load, such as going up a long hill. I kind of accidentally found out that the top half of the radiator remained cold even as the temp light came on. It turned out the upper tubes, where most of the cooling would occur, were clogged with hard water residue. I took it to a shop to have it cleaned out for like $50, and it worked great to the day that I sold it. That was an old brass radiator with end tanks that were soldered on. I'm not sure if you can do the same with the Aerostar's aluminum tanks that are glued on.

Jose,

Did you take any actual temp measurements at the radiator? Like with either a contact type thermometer or one of those IR sensors? You can compare these readings to your other vans where the temps read more "normal"

 

xlt4wd90,

no I haven't, now you're getting me into hot water (no pun intended)

besides, my 1986 and 1992 were sold, I have no way to check them either.

 

Last summer on my 97 3.0 the bypass pipe that the temp gauge sensor screws into started leaking. After replacing it, my gauge went from running around the R to running right around the A in normal. Replaced the sensor. No change. Replaced thermostat. No change. Installed complete aftermarket gauge. Read 240 degrees. The highest reading I got with an IR gauge was 210 with ambient temp over 90, A/C on. The van was driven all summer with this reading and no physical indications of overheating.