Since my purchase of a 97 AWD extend Aerostar a few months back I have always noticed no matter if it's city driving or a long trip on the highway in relatively cool or warm weather that my engine temp. gauge nerver goes past the "O" in NORMAL in the gauge. Actually, it normally sits right between "N" and "O". Is this something I should be concerned about? I have noticed the gas mileage is not that all great either, 14mpg in city and 18mpg on highway.

Is my thermostat stuck open? I would rather have it run on the cooler side especially with the HOT summer months fast approaching. Any information or comments are welcome!


Thanks!

 

In reality a open thermostat is not as good as a working one. The water has no time to be cooled, So it will run hotter.

Most fords run low temps anyway. Your gas milage might be a bad plug, wire, or 02 senser. If it runs and idles fine I bet the 02 went bad.

I had one in my 89 EB 3.0 go out and the only reason I knew something was up was the computer was showing 14~18 MPG when I was getting 19~23 MPG.

 

Be glad it's running cool... Mine usually stays between the 'm' and the 'a' in normal... I wish it ran as cool as you describe you describe.. probably need a thermostat and radiator in mine... water pump is new.. hoses are also new...

I normally run between 18 and 22 mpg on the highway... depending on speeds, the slower the better.. it drops to around 15-16 in city stop and go driving... Most people say that theirs run around 18-19, so that isn't any thing to worry about... now the impact on your wallet may be another issue...

With the lack of aerodynamics of an aerostar they are not know for great gas milage... Sure can be fun to drive though.. Been the best car I've owned... I have to say i'd definatley buy another one.. only thing I hate is that that engine bay is so tight....

 

1997 Ford Aerostar Extended AWD
4.0 liter V6
120,000 miles


Recently done:
Bosch platinum 4 plugs
Bosch wire set
Wix fuel filter
K&N air filter
Wix oil filter with Rotella T Synthetic 5W-40
Cleaned MAF sensor
Cleaned throttle body
Cleaned IAB motor
Rear differential oil change

Soon to be done:
Wix transmission filter with Valvoline synthetic blend Mercon V
Front differential oil change
Transfer case oil change
Right side CV boot replacement


That about sums up my vehicle condition mechanically for the above post for a better response to my question.



Thanks!

 

My '96 4.0 had an open thermostat. I replaced it with one that worked, and my mpg improved. I've driven it across Arizona on 108+ degree days, with no overheat problems. (127K miles)

 

My '95 4WD typically runs around the "O" and I get about the same mileage as you. Even with a mix of city and highway, it rarely gets over 15, unless most of the miles are highway. I have noticed that speed makes a huge difference in mileage on the highway. If I drive 70 mph indicated with no headwind, I'll get 20 (sometimes almost 21), but if I go 75, mileage will be about 18. Drive through Ellensberg (where there's always a headwind no matter which direction you go), and mileage goes down to 16.5-17. So, depending on your driving habits and where you drive, the mileage isn't unreasonable for a 4WD Aerostar. Driving all four wheels full time is about a 20% penalty.

From my experience, when the thermostat has stuck open, temperature barely gets up into the normal range and it takes a long time to get there. If the thermostat is working, it won't take too long for the needle to get to its normal spot and you should be able to notice the temp gauge cycle slightly but it will take some patience to observe this when the engine is idling. I replaced my temp sender unit when I replaced the heads, and the gauge read on the "A". I just about had a heart attack. I put in the old unit and the gauge went back to where it used to be normally. Moral of the story: due to variations in tolerances of the sender, not all gauges will read the same. I wouldn't be concerned unless there was some change from the way it's been reading.

 

Headwinds are a big factor in gas milage, especially with a 3.0l v6 in something like an aerostar. It has to work so hard to beat those winds. On interstae 20 going into Columbia, South Carolina there is almost always a Headwind that my dad has to fight with. He does not drive the aerostar on his commute anymore because he needed more power. now drives a Plymouth GranFury with a 318 V8.... lots of power to handle the interstate drive... gas mileage in that is the same though, of course with his driving what else would I expect...


Anyway, another point that needs to be made is that a lack of cooling system maitenence can corrode the water pump as well as the engine block, especially aluminum because it creates some kind of electric current with the metal which leads to corrosion... I don't think the aerostar has an aluminum block or heads though, maybe the water pump... still, If you leave it for too long you may find the bill could get really big really fast. If you know it may not have been flushed and had fresh anitfreeze-water mix put in it recently, do it... it's worth it. I need to replace my radiator, thermostat, heater hoses, and probably the fan.

Ah another question. How difficult would it be to switch to an electric fan?

 

My '95 EXT AWD with the 4.0 liter V6 warms up quickly, even when the ambient temp is below freezing, but the temp gauge never gets above the "O" in normal. Gas mileage is ~15mpg around town, ~20 on the highway. Just my $.02's worth.

 

I had the temp gage thing with my 91 last year. I thought it was normal until it got to be 30 degrees outside and I had no hot air from the heater. The thermastat was broken and very open. Replaced it and I had heat. I had a normal reading on the temp gage. Tony

 

After reading this post I had to see where the temp gauge ran in our Aerostar.

This afternoon in 108 degree weather with the air on Max at 65 MPH it was between the R and M in NORMAL.

We've had our Aerostar about 10 months now,
it had 48K on it when we bought it and it now has about 56K.

We put over 3 K on it the first month we had it, by driving from here in Calif. to Oklahoma.

I really fell in love with that van on that trip.
cruising I 40 at 70 to 80 MPH and we got 350 to 400 miles from a tank.

You can drive out a tank full and don't even want to give up the drivers seat, one of the nicest vehicles I've ever owned.

 

I had the same feeling. The thing just fits me. It rides good, Gets good MPG, Can be anything you need at any given time. It has it's week points and stuff but I can live with most of them..