When I bought my '93 Aerostar (with 20K mls on the clock), engine temp was always between N and O. Since last year, I have also experienced the "erratic temp gauge" syndrom. Now last Sunday, on a longer highway trip, the needle remained on M. I have a suspicion that the fan clutch is fading out. Any comments?

Tom Ucen
1993 Aerostar XL Ext. 3.0L
Munich, Germany

 

Check the thermostat. Has it ever been replaced? It maybe due for replacing.

 

Ditto the thermostat. They are always going out. Even if the fan clutch was gone, at highway speeds there is sufficient airflow to cool the system.

 

thanks for the answers. The thermostat has in fact never been changed.

Tom Ucen
1993 Aerostar XL Ext. 3.0L
Munich, Germany

 

Well, I am going to have to disagree about the fan clutch. I am speaking from very near experience. I too, had an overheating problem with my 92 Aerostar with 3.0L, it didn't matter if I was at highway speeds or not, it just ran too hot. It did run cooler at highway speeds but not very much. I couldn't run the air for very long, because it would overheat. I am in Arizona, BTW, the testing bed for this sort of problem.

I replaced the thermostat with no change in temperature. When I drained the coolant, I noticed that it was a little sludged up at the petcock. I decided to replace the radiator with the extra tubing in it(heavy duty), it is basically twice the width of the original, very little change in the temp. I finally decided that I would replace the fan clutch. This turned into a night-mare, as I couldn't get the cluthc off of the water pump. I ended up pulling the pump/pulley/fan/fan clutch assembly out, after removing the radiator again. I had to cut through the clutch extension to get the fan and pulley off.

Well, after getting all this done, the van actually sounds like a school bus now. I can leave it running with the air on indefinately in 110 degree tempatures without it overheating. Of course, now the heater hoses are started to leak. <GBG> I am having too much fun...

Terry
'65 Ford F100
'92 Ford Aerostar

 

Actually, I haven't had time to do anytime about it. But last weekend, we took a long trip and the temp needle was on "O" all the time. Conditions were outside temp in the 90s, Autobahn driving at 80-90 mph with A/C running at max position all the time.
Next weekend we're going to Italy on vacation. I'll sure be watching that gauge......

Tom Ucen
1993 Aerostar XL Ext. 3.0L
Munich, Germany

 

A comment and a caution. I have a 93 4.0. I experienced the same fluctuation problem after a water pump change. Actually there is a tech bullitin out from ford on that same issue. My fluctuation problem corrected its self. I think as I recall, it has to do with air in the system.

A caution: I found out in a very costly way that if your coolant level drops below the sensor, it doesn't read hot. The sensor has to be immersed to give a true reading. Now I will be removing a over temped 4.0 motor with a blown head gasket.....

 

Hmm, where exactly is that sensor? Whenever I check my coolant, the level never reaches up to the filler neck in the radiator. So I go ahead, top it up and the next time, it's low again. There's not much to see in the overflow reservoir.
However, the fluid level is never THAT low to be critical.

Tom Ucen
1993 Aerostar XL Ext. 3.0L
Munich, Germany

 

Well, the journey to solve the great mystery of the overheating was a three part odysey for me. Everyone knows that everything comes in threes.

To begin with, I have a '90 Aerostar with a 3.0 and heavyduty transmission. It's also rigged with a towing package. To date, I have over 199,800 miles on it, and I still have that original engine and trany. Everything else has nearly been replaced over time.

Anyways, the overheating. It didn't effect my Aaerostar until quite recently. I made a two day trip of over 1800 miles when the temperature went way up and I had to stop at the side of the road to cool at the last leg of the journey.

First I thought that it was the radiator, because the temp guage fluctuated as if the coolant had a hard time getting through the system. I thought it was a clogg. I got a flush done and thought that was it.

No sir! It wasn't done. I then thought that it was the transmission because the temperature would be highest in the lower gears. I got the filter and fluid changed. And yes, the temperature was still crazy. For a while I thought that I had a faulty temp guage, because how could the temperature flunctuate from the redline back down to normal in half a second? I took this belief with me to Banff. It was a 750 mile drive.

When I got back from the trip, the van was still with me, but there was no sperking from the plugs, as that part was sensitive at high temperatures after a while. The plot thickened.

I called the place that I got my work done and told them what was going on. They mentioned the thermostat. Why didn't mention that sooner? Nice people. Anyways, I have it in now and I hope to God that it's the end of the high temperatures, and loosing the sperking.

And here I thought I knew my van well. Dito to the thermostat.

 

Seems like the problem corrected itself. During my recent vacation in Italy at very hot temperatures, car fully loaded, A/C running at max and highway speeds around 80mph, the needle was around the "o" and "r" all the time. No fluctuation at all..

Tom Ucen
1993 Aerostar XL Ext. 3.0L
Munich, Germany

 

 

Well, the thermostat was definitely the problem. However, when I went to get it fixed, a new bag of lemons dropped. But, there is a good fix for that.

The intake manifold that houses the thermostat was siesed to the engine block. Not only that, the bolts were all corroded. They snapped off the second they made them budge. The mechanic broke his ratchet trying to get them off.

Anyways, they asked me how far I wanted them to go with it. I asked, "what would it mean?" It would mean $1000 plus dollars in labour discounting what ever problem may rise up in the process. They said my '90 Aerostar 3.0 wasn't worth that much. I agreed, and said forget it.

However, I discovered a quick fix for this higher temperature problem.

What you do is you disconnect the intake hose from the radiator that goes on top of the thermostat manifold. You then use a screw driver to pop the thermostat valve out of its casing so that the coolant could get bye the little gap the valve then has. The coolant will start to flow again and regulate the temperature of the engine way back down to the normal levels.

The guys at the garage said that it'll do for the summer, but the winter is another thing. Nevertheless, I tried out my heat with the temperature guage up just below the "n" in normal. I got lots of heat. In winter, the engine temperature is about a quarter lower on the guage in normal conditions, which the guage now seems to follow.

So, that slight modification of popping the thermostat valve to the side seems to work for me. Just make sure the engine has cooled down substantially, or you'll get boiling fluid that will disfigure you or someone close bye.

It's a lot more cost effective than the alternative. I'll just have to wait and see if I do in fact get the heat I need in the winter.