Overheats

Tiny
COLINA7413
  • MEMBER
  • 1998 FORD ESCORT
  • 2.0L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 163,780 MILES
I bought this car last night 8/2/2017 it is the zx2 model. It drove really well. When I got home and put it in park and let it idle for a bit it slowly began to overheat. I let the engine cool then checked coolant levels and all was normal. Radiator had clean coolant in it and the cap was good. Also, there are no leaks of any kind. My husband thinks it might be the thermostat or radiator fan. How would we check for these issues and any other issues to look for? Thanks!
Thursday, August 3rd, 2017 AT 12:41 PM

6 Replies

Tiny
STEVE W.
  • MECHANIC
  • 15,237 POSTS
Sounds like the fan is not operating. If it was the thermostat it would have overheated while you were driving it. However it did not until you stopped and the air stopped moving over the radiator.

The fan uses the coolant temperature sensor and the combined relay as its controls. It should turn on when the coolant hits 221 degrees or when you turn on the AC.

First check that the 40 amp fuse that powers the fan isn't blown. It is in the fuse box under the hood.
If it is okay, you can test the fan by using jumper wires to direct battery power to the fan. Unplug it and use a wire to connect battery positive to the green with yellow wire. Connect battery negative to the black wire, the fan should run on high speed. Disconnect the wire from the green/yellow and connect it to the yellow and the fan should run on low.
If that checks out you will need a good scan tool to test the control relay and to see what the coolant temperature sender is telling the PCM.
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Thursday, August 3rd, 2017 AT 1:37 PM
Tiny
COLINA7413
  • MEMBER
  • 4 POSTS
The fan works. I have no idea what you mean by pcm or even where these are located in the engine or what it looks like. We replaced the fuse as well. Please help
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Friday, August 4th, 2017 AT 11:12 AM
Tiny
STEVE W.
  • MECHANIC
  • 15,237 POSTS
When it gets hot the fan comes on? Or did you test it and the fan worked when powered with a jumper lead?

If the fan comes on when it gets hot, but it still heats up you likely have an issue with a partly plugged radiator.

If on the other hand you tested the fan and it works when powered but is not coming on when it gets hot you will need a scan tool to test the remainder of the controls.
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Friday, August 4th, 2017 AT 11:34 AM
Tiny
COLINA7413
  • MEMBER
  • 4 POSTS
Works when powered but not coming on when hot. What are the remaining controls I should test? Thanks
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Friday, August 4th, 2017 AT 12:16 PM
Tiny
COLINA7413
  • MEMBER
  • 4 POSTS
Fan worked with jumper lead
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Friday, August 4th, 2017 AT 12:17 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,237 POSTS
Well for the rest you really need a good scan tool. With it you can watch the actual temperature the computer sees, you can also go in and turn on the fan through the computer itself. No way to do either of those without the scan tool. Mainly because they didn't use a separate relay for the fan, instead it's in a combination relay that controls the fan, fuel pump, powertrain power and more all in one.
At this point having a shop test those items to find the problem would be a good option. The relay unit is over $300.00 on it's own. It could be that, the engine coolant temperature sender or an actual fault in the computer.
Unfortunately there isn't a way to really test those without a scan tool.
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Friday, August 4th, 2017 AT 3:46 PM

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