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4 Posts
Discussion Starter #1
sup guys have a problem and looking for feedback. we have had the car for about a month. it runs very good and gets great mpg. however it always seemed to be running really hot. is that commom for the 1.9? in fact i don't ever recall hearing the fan kick on at all. i listened for it. anyway today the car lost power while driving with no responce with stepping on the gas. started up once we stopped ran then died. i popped the hood and it was very hot. i tried to start it again and it started but would not rev while in park. there is a cooling light that comes on the dashboard every now and then. is it the fan? the fuse? thats all i can think of. however i let the engine cool for a bit started it up and it ran fine. must have overheated. thanks for any imput.

119 Posts
Usually this kind of dimmed lights is a sign of a bad ground either to the cluster itself (that I doubt) unless you recently messed with it or most likely to one of the taillights. I am not sure if it's possible at all but it would help to check liftgate wiring if it's a wagon.
Check the ground to the engine as well, just in case.

149 Posts
I've been working on a better understanding on the Cooling system of my
1991 Pony Escort. Here are a few possibilities:

1. Fan Relays. One is activated at 215f to 220F and is called the Low
speed relay. It's controlled by pin 35 of the PCM. The other is the High
speed fan relay and is controlled by pin 31 of the PCM and it activates at
230F. Both relays are supplied by a main fan relay in the Fuse box over
the driver side fender. The first two are mounted together in the fender
behind the air box.

If you have AC you have a two speed fan. If you don't it's a one speed
fan but still has the same relay circuit, except two of the three Radiator
fan wires are connected together in the Radiator fan harness.
Therefore if the High or Low speed relay activates, the fan comes on at
one single speed in both instances.

Be aware that as soon as the coolant temp drops below 215 the fan may
turn off again. At idle you may notice a load on the engine when the
Radiator fan activates. Sorta like when the AC clutch activates.

I not sure but the fan may automatically turn off after the car obtains a
speed above 50mph.

2. The ECT (Engine coolant Temperature) Sensor. It tells the PCM how
hot the coolant has become. It's the main way the PCM makes decisions
about the control of the engine and your Radiator fan. As I understand
once Pin 7 of the PCM sees .55V to .45V and the Low speed fan will activate.
This is where the ECT comes in, as it decreases resistance as the coolant
temp rises. Through voltage division involving the ECT and the PCM the
voltage correspondingly drops at pin 7. Mine doesn't come on until the PCM
sees .45V at pin 7. That is I believe above 220F. That's a bit past
"L" on my temperature gauge. It concerns me and I'm trying to
understand why it waits so long to activate. I do know that the Gauge
respond faster to the temperature increase than the slower ECT, and may
explain somewhat why this occurs.

The ECT is on your heater inlet tube. It's the bigger sensor of the two
normally found here. If it's still stock it'll appear grey in color. My testing
indicates that the MotorCraft ECT gets to the fan trigger point about 5F
sooner than an after market sensor I tested. If you have 3 sensor's it's
closest to thermostat and has the thinner nut of the two largest sensors.

3. The Radiator Fan is bad. One way to test part of the Circuit
is to partially disconnect your ECT connector. Then at idle carefully reach
in and unplug the connector fully. Either the low speed or high speed
relay will activate and your fan will turn on at that speed. I'm not sure
which relay activates yet. Clear the codes after this action by
disconnecting the battery for 5 minutes as it may register a false error.

4. Check all your fuses and pay special attention to any burned areas
of the fuse compartments.

5. Replace your radiator cap. To prevent boil over the cooling system
needs to maintain 10 to 13 psi. If the cap releases too soon it'll boil over.
Too long and the cooling system will find a pressure release somewhere
else like a head gasket. DON'T replace the cap while the engine is hot of

6. The radiator is clogged up. Drain your coolant when the engine is
completely cooled. If you drain the coolant you can test radiator flow.
With the drain cock closed, disconnect the hose at the bottom and the
disconnect the hose at the top from the thermostat housing. Take the
water hose and connect to the top radiator hose. Turn on the water
and the water should flow freely out the bottom hose connection point.

At operating temperature You can also feel for consistently cool spots of
the radiator. Indicating no flow.

7. Air in the Coolant system. Burp the coolant of air. I usually rock the car
a bit and some start the car with the cap off. Then add coolant at the
radiator cap. Do all WHILE COOL.

8. Stuck or defective thermostat. With a cool engine You should feel the
top radiator hose rapidly get warm once operating temp is obtained.

9. Replace the coolant with no less than a 50/50 mix. Use only distilled
water to reduce corrosion.

10. Defective water pump. My experience with other cars is the pump will
weep coolant or make noise, and rapid overheat at idle.

11. Cracked Radiator. Inspect mounting points for leakage.

12. Blown Head gasket. Reduced coolant pressure results. Coolant in
exhaust exhibited by consistent white wet smoke. Coolant reservoir may
gurgle after engine is shut off as well.

149 Posts
13. Blocked Heater Core. If you change the Thermostat don't miss the
opertunity to easily test the Heater Core. Once the Thermostat Housing is
off one can simply put the water hose into the short rubber hose
connecting to the Sensor Tube. Then disconnect the hose on the other
side of the Heater Core at the point it connects to the Water Pump.
Point this hose to the ground. Turn the baffles to full heat at the console
and turn on the water hose on. Water sould freely flow without restriction.

If you have a length of heater hose you can bypass the sensor tube and
go straight into the core at the firewall.

If you have a blocked Heater Core the heat produced into the interior
of the car will low to none. This can also be a sign of low coolant, air
pocket, or loss of coolant pressure via the Head Gasket.
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