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Discussion Starter #1
Got a '11 Crown Vic base model w/ 270k miles I'm using for a delivery vehicle and I'm trying to drill down it's overheating problem. It started overheating this summer when sitting idling when outside temps were over 90. Parking it in the shade or opening the hood (while still running) would get the engine temp back down to normal. But last night something new happened. It started overheating at night with outside air temp at 70, so I guess whatever it is has gotten to the point where a part needs to be replaced. Coolant is full btw.

This car is new to me as of 4 months ago, and I don't have a lot of experience working with this engine so I'm not sure where or how to start diagnosing it. What do I look at to start diagnosing? And if no hard evidence shows up pointing to one thing or the other, what part should I change out first? I would guess thermostat and water pump.
 

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Is the engine cooling fan cutting in ?


If you look down below your post in this section you will see a similar overheating post and replies on engine cooling fan problem.
 

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Discussion Starter #3
Fan seems to be doing fine.


After watching it overheat a couple times now a pattern has emerged of coolant leaking from under the reservoir cap while the dash temp gauge still reads normal. After that the gauge goes up to full overheat. What would leaking around the reservoir cap indicate in this situation?
 

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Try simple thing first , change cap . Could be thermostat sticking , try bleeding cooling system but shouldn't really need to .Radiator could be partially blocked but other possibilities .You may have to get a block test carried out if still pressurising and overheating .
 

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Discussion Starter #5
Ok shoot I was wrong about the rad fan...it's actually NOT turning. Here's what I'm seeing...


1 - The overheat condition doesn't happen while moving, it only happens while in park after idling for a while

2 - Top radiator hose DOES get hot

3 - If the a/c is off, the rad fan DOES NOT turn at all during overheating as the temp gauge moves all the way up

4 - At normal engine temp the rad fan DOES turn as soon as the a/c is turned on, but I've only observed this so far at normal temperatures.

5 - During the times it overheats and the a/c is on, the cabin vent air gets hot and humid right when the overheating occurs. I haven't yet made it a point to check the rad fan at this point to see if it's still turning.

6 - During testing, after getting the engine temp up to idle hot and the temp gauge read normal in the middle, to trigger it to overheat I had to run the engine at 2k rpm for over 5 mins before the dash temp gauge began to rise. After the gauge begins to creep up I've let off the gas but the temp continues to go all the way up. Although to trigger the overheat condition I ran it at 2k for a while, it DOES overheat by simply sitting in park and idling.

7 - The coolant reservoir cap has a small leak but I don't think this is a major factor. I've continued to top off the reservoir throughout my testing and overall there doesn't seem to be much coolant leaking from the reservoir. Although, you CAN hear air seep from the reservoir cap when you squeeze the top rad hose.

The main problem seems to be the rad fan not turning. Any ideas? I'm all ears.
 

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jwko
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Re: Cooling system building pressure and overheating
Hi Kpbarst123

I've read where some have had problems with the fan not kicking on causing a overheat issue, especially at idle.

If its not coming during a near overheating episode, check the cooling fan and make sure its good then check fan control module and the coolant temp sensor.

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Re: Cooling system building pressure and overheating
To add to jwkos advice , check this out . If still having problems after this , get back to the forum and you will get further advice on other possible causes .

This is the correct way to trouble shoot the radiator fan module on the 06-11 Ford Crown Victoria they are easy to trouble shoot and swap out for the new one.
Check for power to module- no power check fuse check fan - if fan does not power up by jumpering it then replace fan motor
check output -power from module to fan if greater than 10 volts replace module

 

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Discussion Starter #7
First, replaced reservoir cap and thermostat with new


Then did some more testing by way of observing the fan speed when turning the a/c on and off. Fan speed seemed sluggish as if it wasn't being properly commanded. At different points it seemed like it wanted to turn but would stop. Maybe a dumb idea but after turning the a/c off and the blades came to a stop I took a small twig and gave the blade a quick push and it slowly started going again.


So what is this a bad fan motor maybe? And if so, where do you get just the motor? Can't find it at any of the major car store sites.


I've also read the connectors on either end of the fan control module (connected to the fan body) can get corroded.
 

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I did all these checks and the module and motor check good. I assume that the small wire on the supply plug is the control wire. It has 0 volts all the time. That doesn't seem right to me. Where do I go from here? BTW this is on a 2007 Merc GM.
 

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I just got done replacing the cooling fan assembly in my 08 GM. I did the checks. Fan was good. Module had 12 volt going in. Output was less than 10 volts (per that video posted.) But the voltage was very low and kept varying. Still, the fan would be powered by the module. I think there is more to the story that less than 10 volts/its OK. I have the new fan/module assembly and out of the car, plugged it in and turned on the A/C. Works like a champ. Installed and DONE.
 
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