On 2 occasions, my wife reported a massive cloud of steam coming from under
the front of the fan, both time after a cold start-up and idle of approx 15
min to an hour. It appeared (I was unable to see this happen myself, and
wife's description was less than helpful) that it may have "boiled over" and
ejected the coolant through the reservoir, running down over the exhaust
What could cause this? One suggestion was a sticking thermostat, any other
ideas or confirmations? I really can't afford a trip to the garage for trial
and error, and I can change a thermostat myself.
Thank you all...
if it overheats its a thermostat.
It could also be a temperature sensor which provides a faulty reading,
and the computer doesn't turn on the FAN.
I don't know about 3.8, but on 4.6 there are two temperature sensors,
one is for gauge, and the other is for computer which controlls the
FAN. They can be tested for a resistance.
Good preventative maintenance item, replace the tstat with an OEM
version. I've had aftermarket tstats fail in a short time (couple of
years whereas the OEMS go for more years).
On some (most?) Fords, the fan switch is a simple temperature actuated
open/close switch that should close around 220 degrees F, located near
the tstat. Signal then passes through the fan switch and probably
energizes a relay coil that pulls the contacts in to energize the fan.
I've had these get flaky after a long time as well.
A/C and defrost have another path from the A/C module or computer to
energize the fan, bypassing the relay. In the meantime, just tell the
wife to leave the defrost on, this should keep the fan running
constantly if everything else is in order. You can get by this way
with a bad tstat and fan switch.
Anyway, my point of reference is only having worked on one Ford that
exhibited similar problems, severe temp spike at idle. Some Fords
might be different then the way mine was setup, but can't be that much
I have a little experience with Ford vans. More with wives (wife, only one,
so far). My wife might report a wisp of vapor as a "massive cloud". No, not
might, she would.
Just some things to think about...
Is she seing exhaust blowing under the car and out the front? Assuming the
wind is from behind the car.
Could it be a damp engine heating up?
Is there coolant on the driveway?
Is the coolant level ok?
Somebody asked if it overheated. You might point out the gauge to her and have
her watch it.
Better yet, drive the van for a week or two yourself and see what happens.
Let us know what (if anything) you find. I'm curious.
both times this occurred my wife was at work, this would happen on the
parking lot after a ridiculously long idle. I know the source of the steam
was blowover from the reservoir that ran down over the exhaust pipe, I saw
the evidence after the fact (coolant on inner fender where reservoir is). In
the times since I have tried to recreate the scenario, but to no avail. I
have yet to hear the fan start up just the same, which takes me back to an
The cold season is here where we live (Alberta), so the fan may not be
wanting to start much anyway. Next warm day me and my trusty DMM will check
out the sensors and fan.
On another topic that may or may not be related, I have yet to have the rear
heat actually blow heat, only cold air. It has been suggested to me the
system is airlocked, which could cause a "boil over", so I am told. I have
no idea how to clear the airlock.
And last but not least, is it normal for the AC clutch to engage and
disengage randomly while sitting at idle, AC inside switched off?
First, when you turn A/C on the cooling fan should come on which proves the
electr. fan circuits are ok
You could still have other problems causing the fan not to come without the
A/C on but at least you \know the fan works
And yes, a/c cycles in defrost and defrost/floor mode to get humidity out of
Ahhh, OK, I suspected that, but wan't sure (AC to dry air). I knew other
manufacturers did that too.
Thanks for the tip on the fan check, easy one.
This is a great group, thanks to everyone. It is good to see a NG where
everyone is helping each other, not insulting everyone at random. Guess is
says a lot for the mentality of the users here!
I will attempt to contribute myself with what little I know when I can.
Dismantler - Did you ever find out the problem with the boil over coolant?
My wife's Windstar just did the same thing, but while idling at a stop
light after driving 15 min. or so. Thanks for the help!!!
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