So I wanted to give everyone an update on the repair that I did on my 2011 XF 5.0l. I had posted earlier where I reported that my car was giving an "overheat condition" warning on the dash. I was only getting that in heavy stopped traffic or while sitting for extended periods in the drive thru lines at our local fast food shops. Every once in a while I would get the same warning if I ran the air condition while I was traveling slowly on residential streets. The car never really overheated enough to lose coolant. But it was obviously at the top of the safe operating range.

So I posted the question here to see if anyone had any similar issues. I only got a few tips like to check the thermo sensor and a recommendation to replace the thermostat. But the clues that I had on when the car overheated led me to do my own diagnosis.

I first changed the thermo sensor near the thermostat housing just because it was an easy and inexpensive thing to try. But that did not work.

So my next thing was to do what any real mechanic should do. And that is to really find the problem and to change as little parts as possible in order to cure the issue. So I got my infrared tester and duplicated the overheat condition as I periodically checked and recorded coolant temperatures at various cooling system locations. I did find that the temperatures were very consistent at nearly all points when the car got to the normal operating temperature which indicated that the thermostat had operated correctly. Additionally, when the car got hot, the temperature was pretty consistent at all the points that I tested.

I then tested the power connections on the electric fan harness. There is a red wire, a black wire, and two smaller wires. I knew that the Jag had a small electronic box on the fan assembly that controlled the speed of the motor as well as when the fan came on and off. The red and black wires are battery wires that are not switched with the ignition. So you will get a power reading on the red wire as long as the battery is connected. The black is a chassis ground. And the two smaller wires I am assuming are control wires from the vehicle's engine management computer. I did not check the values that these wires are supposed to have. But I did get a signal which indicated that there was some activity.

So I next observed the operation of the fan at various temperatures. At certain points, the fan wiggled a little but never turned on to help cool the radiator. So knowing that information, I determined that I had a defective fan assembly. There is no way to test the fan control module on the fan assembly since it is a sealed unit and permanently mounted to the back of the fan motor.

After replacing the fan assembly, I started the vehicle and ran the same coolant temperature test that I previously did. The fan kicked on as it should at operating temperature and ran at various speeds dependent on the temperature of the coolant. That is exactly what it should do.

So I reinstalled all the components that were removed for access to the fan assembly and test drove the vehicle to confirm that the repair had been done satisfactory. Everything checked out.

The whole repair is pretty simple to do and anyone needing help can send me a PM. I may post a step by step thread to show how easy it is to replace the fan assembly if anyone is interested. The whole repair took less than 30 minutes.

Performing the proper tests to diagnose the problem can save a lot of time and money. Even professionals like myself often jump to conclusions and change parts that are not truly defective. This can increase repair costs to the consumer.

 

Repairs like this will be invaluable to this forum and future owners of aging XFs. Good job

 

Excellent detective work! I wish more techs at dealers/shops would think link you did to replace as few parts as possible (aka the *real* problem).

 

Thank you Mr Sharky for a description which is much more valuable than just a how to on fixing a fan. It explains the logical troubleshooting procedure you used.

 

Very nice work!

 

Great information.....thanks for posting!

 

Good job!!

Can you post the part number and cost of the fan assembly?
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Thank you for posting this, this is great knowledge for anyone facing a similar issue.

 

Excellent write up

 

Excellent work

 

Hi,

I have the same problem as you. The rad fan doesn't appear to be doing its job. Can you post some quick instructions and part numbers please?

Thanks,

 

oldie,
I replied to your thread. The problem lies in the controller which is part of the fan motor assembly. You must replace the complete unit. You can buy one inexpensively on eBay. There is no fuse and it is hard to test the sealed controller unit.

Ed

 

Nice job, Good information..


Did you get the Fan assy at the dealer's or some other Auto-parts vender?

 

So the dealer says that it's the water pump. Not sure how that works but he says he was able to engage the fan just fine. Apparently the pulley is wobbling quite a bit. We will see how it goes when it gets replaced.

 

Water pump may need replacing but that wouldn't explain why the cooling fan doesn't work. Even a bad water pump would not prevent enough coolant from reaching the thermo sensor which activates the fan.

 

That is the problem with technicians at a dealership. They rely on a flow chart to tell them which part to replace. Old mechanics use their intelligence to find the real problem. In my opinion, unless your pump is leaking water from the seals, it has nothing to do with the overheating. I can safely bet that after he changes the water pump, he will find out that the problem is not solved and your car will have to sit and wait for cooling fan assembly to be ordered and installed at your expense.

 

Great thread...

Can we get this post (or something similar) added to the sticky? There are several posts about water pumps, and this one about the fan needs to be added...

Cheers, Will

 

So today was nice and warm and I got to test the fan controller. Car still overheats, just like Ed says. Overheating happens in the same way - at idle. Fan doesn't turn on. Not very happy with the dealer at the moment.

Ed, would you be able to post a link to a compatible fan on eBay (or the one you installed)? My search turns up one fan and I'm not sure how to check if it's the right one.

 

I'm looking at the replaced water pump right now at the dealer. It doesn't spin freely and the pulley has a very slight wobble. It makes a very slight grinding noise as it spins.

I'm going to take the pump home, take it apart and post pictures into a water pump thread.

Told the dealer I shouldn't pay for another diagnosis since they got it wrong the first time. Depends they said. We will see what happens. I'll update as I learn more

 

Dealer wants $1600 to replace the fan assembly and would only comp 1 hr of their diagnosis. The part is 4 days away. What a bunch of bs. Livid right now.