Fan Clutch Noise then engine overheats - 4.6L V8 | Ford Explorer Forums - Serious Explorations

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Fan Clutch Noise then engine overheats - 4.6L V8

Carts2Wheels

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Year, Model & Trim Level
2007 Explorer Limited V8
Preface: I did do some research and found a few similar threads/issues but nothing exactly like what I'm experiencing so I decided to start a new thread.

2007 Explorer Limited, 4.6L V8
149,000ish miles

I recently started to see significant fluctuations on my temperature gauge, a few times so high it tripped the dash warning.

The scenario goes like this. Driving the truck and gauge reaches normal. Once I experience some stop/go or waiting for a car wash or something along those lines I can hear the fan clutch engage and start the loud whirring noise form under the hood. Accelerate away, noise increases as engine speed increases, don't think much of it until I notice my temperature gauge rise rapidly. It stays up for a while, when the fan disengages (I no longer hear it), the temp drops back down to normal rapidly. If I accelerate hard a couple times while the fan is whirring it pegs.

One thing of note that I didn't see in any of the other threads...the temp only RISES when the fan noise is occurring, otherwise the temperature gauge stays normal.

This past weekend I replaced the thermostat, problem still persists. I've read some forum threads and have the following possibilities to start into next: fan clutch replacement, water pump replacement (but wouldn't it always run hot?), air charge temperature sensor, PCM software update.

Anyone have any thoughts on this? It baffles me that it overheats when the fan seems to be engaged but not any other time. Thanks in advance.
 



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The fan clutch is being signaled to engage fully as the temperature of the engine begins to rise. The gauges on these instrument panels are programmedTo remain in the normal range even as the temperature climbs in till it is approaching full overheat temperature. Essentially they are no better than in overheat light, because they will not show you the “getting hot” reading we would like
 






So where would I start looking for the next issue then? Bad fan clutch and why it calls for it to run more often and why the engine overheats when it is running because it's not doing it's job?
 






I think michael's point was that the fan is a symptom of the problem - not likely the actual problem itself. Have you done the basics like check your antifreeze level? I see that you replaced your thermostat - that was a good move. Have you made sure that all the air is out of the cooling system? If you have rear heat then in order to get rid of all the air you are going to need to run it with the front end higher than the rear. Either jack up the front end or find a hill. Your water pump could still be the issue - the pump vanes could have worn to the point that under normal conditions enough water is circulated to keep thinks under control. Under stress though, it does not have the capacity it needs.
 






How is the Cylinder Head Temp Sensor? Reading correctly? And the wiring to it?

I'm hearing the fan clutch engages, temp rises, and then falls when the fan clutch disengages. What signals the fan clutch to engage? The temp sensor... Bad signal from the sensor (or bad wiring) could be part of it too...

Are there any other physical symptoms of an overheat? Coolant overflowing or way too high? Overall Engine temps seeming way to hot?
 






Mine did that when I changed the heater hose and again after the new radiator. Its was air in my system which was kinda of hard to bleed out. But once I got the air out it has been great.
 






Update / Resolution:

Time factors & this being my DD forced me to go to the dealer. They found that there was a lot of trapped air in my system so they pressure bled it and all was good to go, for a little while. Then upon arriving home one night, fluid was leaking out of the rear heater...and temps were moving again so I took it to the dealer again. There was a failure in the lines so instead of pay the exorbitant cost to replace the line to the rear heater, it is not bypassed and have been good ever since.

Thanks for everyone's help!
 






... The gauges on these instrument panels are programmedTo remain in the normal range even as the temperature climbs in till it is approaching full overheat temperature. ...

Michael, where did you get this info? It seems odd to me as the gauge does show the actula transition from cold to operating temp (in the middle of the gauge) as the truck heats up. I find it very odd that the temp gauge would act any differently from operating temp upwards???
 






Michael, where did you get this info? It seems odd to me as the gauge does show the actula transition from cold to operating temp (in the middle of the gauge) as the truck heats up. I find it very odd that the temp gauge would act any differently from operating temp upwards???

That has been my experience also. Having slightly overheated mine once I can confirm that the temp gauge did indeed climb above the normal temp.
 






It’s not just bored, it’s becoming quite common on cars manufactured in the last 10 or 15 years or so.They essentially function as idiot lights except that they will show the warm up from room temperature till 200 degrees in an expected fashion. But the transition from normal operating temperature to overheated comes on as soon as it reaches whatever the programmed temperature threshold is, a lot like a traditional “HOT” light in a car without gauges
 






I'll look this up, still seems pretty strange to me. this would mean you lose all the advantage of warning for a potential cooling problem. 07EddyB is also stating he saw his gauge rise over operating temp...
 






Mine is doing the same thing that the OP describes.

I know this is an older post, but still, it is what mine is doing lol.

When I run the AC, on the highway at speed, it will show overheating on the gauge.

At idle, with the AC off, it doesn't...or at least it didn't a few minutes ago.

Today is a cool windy day, 60 degrees. It's been warmer than this a few times and hasn't overheated till now (after I put a shroud back in it!)..

The fan turns a little sluggish when it's cold, like the clutch is ok...? Is there some sort of "on/off" like an AC compressor?

I'm wondering if my issue is more along the lines of a bad switch or sensor rather than a clutch?

It's an '06 with the V8..
 






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