I have a '93 4 liter aerostar. It has 120k miles. It has started to overheat on steep hills. I have changed the fan clutch and flushed the radiator with sodium citrate. Logic tells me that the problem is caused either by a water pump problem, thermostat problem, fan clutch problem or radiator problem. I could chase the problem with dollars but this does not make sense. Does anyone else have experience with this problem?

 

I own an Aerostar as well, and '87 XLT that looks new, with the 3.0 v6, a4ld auto. Concerning your overheating. The first thing I would do is have a qualified techician perform a flow test on the radiator. Even though you said you flushed it, there still might be some blockage. Even with a restriction on 25% or less, it will cause the engine to overheat. A key is you state that it overheats while climbing hills. Another trick: When the Aerostar is running normal temperature, check and feel the radiator for any "cooler" spots. If you find any, that could indicate a blockage. I'm not suggesting the area will be cold, and the rest "hot", but make sure it is hot everywhere. Some of those radiators also develop blockage from deposits and sediment on the bottom of the tanks inside the radiator, That is what a flow test will determine, and a good technician, who knows what he or she is doing, actually caring to solve your problem, before you start "throwing money" at the cause as you stated. Make sure the thermostat is opening when it should. When the radiator is hot, make sure the top hose is "hot" too! If it is "warm" to the touch, then you indeed may have a restriction in the thermostat, not fully opening, and restricting coolant flow. How is your radiator cap? A common neglected part, that is extremely important. If you have not changed it in a while, do so now. this is one part that do not replace with an aftermarket part. Use the correct Motorcraft cap for your van. In my case, I run a Motorcraft 13 LB. cap that says "motorcraft" and "RS-62" on it. They run about $8 - $9 at the Ford parts dealership, and is worth every penny. I replace mine one every autumn when I flush and refill the cooling system whether it needs it or not. I have never had any cooling problems ever...including the original water pump at 138K. One more tip, that can cause overheating on hills. How is your transmission? Many people don't realize that if your trans is running hot climbing hills, (low or neglected ATF, dirty transmission filter) it will cause an otherwise healthy cooling system to overheat! Once you get on level roads, the overheating problem goes away? That is why I kept thinking about what you said about overheating on hills, when posting my reply. Good luck. If you do determine what your problem was with your overheating Aerostar, please post. Thank You ... Ed