Hello, I have an intermittent problem which was prominent enough yesterday to make some observations, but I'm still baffled.

First things first. 2007 Ranger XLT Supercab, 2WD, AT, 3.0L, 6 cyl. I've only had it a few months.

Sometimes, when accelerating from a standstill (stop sign, traffic light), the engine ROARS when I step on the gas, and will do so to varying degrees every time I press the accelerator until I come to a stop again, at which point it may do it again, or more likely, it doesn't.

When it first happened, I felt for sure that the engine must be revving really fast without giving corresponding power to the drivetrain. After all, it does sound like I'm hitting the gas with the car in Neutral.

But since the problem "switched on and off" several times yesterday, I could see more clearly that this was not the case. The tach wasn't reading any higher relative to the speed of the vehicle than when the problem does not happen. My speed and power is also the same, as far as I can tell.

In other words, the problem is ONLY the noise.

It's weird. It's almost as if whatever sound the truck normally makes is suddenly rerouted out a different path, making a completely different, and much louder sound.

I cannot find words to describe the sound exactly, but I would say that there is a whooshing component to it. Not the whole sound, but some part of it I would call whooshing.

Any ideas? Thanks!

 

Check the fan clutch its most likely failing and locking up, which makes it quite loud

Before starting the engine cold, open the hood and try to spin the fan, shouldn't spin easily, its "cold locked"
Leave hood open and start engine
You should hear the loud whoosh of the locked fan then it should go away within 5-10 seconds
Shut off engine
Try to spin fan again, should be easy to spin, its now unlocked

That's what a working fan clutch should do

 

RonD, thank you!

I will try that, but before I do, can you please answer this?

Assuming I could reproduce this problem with the car stationary, and I were to have visibility to the fan, what should be the behavior of the fan (spinning, not spinning, a little of each, etc.) when (a) everything is working normally (sorry for not knowing enough about how cars work to know this), and (b) under the conditions of the problem that you think might be the cause? I'm talking about behavior on cold first-time startup. Thanks!!

(I am assuming your answer might be that the behavior of the fan is by itself not enough to prove or disprove anything, else you would not have made the suggestion that you did. But I thought it would be worthwhile to ask you this anyway. Thanks for indulging my naivete.)

 

Read RonD reply again. Its a simple check, unless you have no clue what the fan looks like....

 

The fan on the front of the engine is there to pull air in thru the radiator to cool the warm coolant as it circulates thru radiator, thats why the Fan Shroud is there, so it only pulls in air thru the radiator
And to circulate air around the engine bay

Now when you are driving at say 30MPH, way more air than any fan can provide is coming in thru the grill and thru the radiator to cool the radiator, and way more air is coming in from under side of engine bay, so the fan is useless above 30MPH

Anything driven by the fan belt on the engine lowers horsepower and MPG

So the fan clutch was invented, adds horse power and better MPG...................when its working
Its also quieter than direct drive fans

Fan clutch bolts to water pump pulley so that part spins at fan belt speed always
The fan blade itself is bolted to front of the fan clutch so is not directly connected to the water pump pulley

Front part is free to spin on its own
Inside is a light oil and valves
On the front is a bi-metal spring that expands when its warmed up by the CENTER of the radiator
As the radiator and spring warm up it starts to close the valves inside, this causes the fan blade/front of clutch to spin closer and closer to water pump pulley speed so it pulls in more and more air thru radiator
So it strictly heat driven, as you slow down, less air is coming in from the grill and radiator will heat up which causes the fan clutch to lock the fan blades more to pull in more air, the warm it gets then more air it pulls in

On cold start the oil inside is THICK so can not pass thru the open valves easily, this is called Cold Locked, i.e. if you DO NOT start the engine and try to spin the fan it should be hard to spin

If you start the COLD engine you will HEAR the fan pulling in air because it was cold locked, but the oil thins out very fast(5 seconds) and fan is unlocked, if you shut off engine it should spin easily now

If the spring breaks or an internal valve breaks the fan can lock and unlock at random, making noise and then being quiet again

Fan clutches are suppose to "Fail Safe" meaning when they fail they LOCK full time, which is annoying but safer so engine doesn't overheat from no fan, like thermostats are suppose to only fail OPEN so engine won't overheat
But these "fail safes" don't always work, lol

Next time you hear the "noise" shift to Neutral and let RPMs of engine go down, if "noise" goes down with engine RPMs my bet is the fan clutch is Locked

 

Thank you RonD for that excellent explanation. My confusion (I think, and for RoseBud's benefit), was the association between the fan clutch (which you told me to look at) and the fan, which for me is a lot easier to see and identify.

I'm about to do the test (it's evening, but I've not driven the car today), but I want to add something that *might* be useful, since you brought these components up.

Not long ago, I added DIY refrigerant to the A/C. The instructions said not to read the pressure when the fan is stopped. For this reason I was sensitive to the fan's behavior (at that time). The mechanism that I assume is the fan clutch you are talking about, and the fan itself, would cycle on and off in pretty regular cycles, and quickly, like <5 seconds on. then <5 seconds off, etc. I wondered at that time whether that was normal behavior for the fan. Of course, the engine had been running for several minutes at least when I saw this, per the instructions for the refrigerant.

If this info is significant, please let me know. Later, I'll post the results of the test you suggested. Thank you!

 

If it was in regards to AC then they were speaking about vehicles with electric cooling fans, not mechanical fans like Rangers use.
Or AC Condensers, in front of the radiator, some also had electric cooling fans
Or blower/fan for cab air
But any of these should not effect AC pressure all that much, compressor on or off effects pressure

 

OK, after doing this test and rereading everything (and doing a little Googling too), I realize I misunderstood and (and maybe misread) almost everything.

I realize now I had no idea what or where a fan clutch was, and I hope I've got things straight now by saying that you cannot easily SEE the fan clutch; you can only assume what it's doing by looing at the behavior of the fan it's connected to.

I did the test. The fan was indeed a little stiff at first. It was easy to move, but would not move beyond the point that my fingers actually moved it. I could not "twirl" it and get it to move on its own when I let go. Not even a little. Not at all. I assume this is expected for this test.

I turned on the engine, and let it run for about 10-20 seconds. During this time, the fan spun the whole time. The fan appeared to change speeds slightly during this time, based on my observation of a wagon-wheel effect. I assume this is also expected. Then I turned the truck off.

When I tried to spin the fan, I expected per RonD to be able to spin it freely, like it had ball bearings. Well, maybe not that extreme.

But no. The fan was exactly like before. No easier nor harder to turn.

I tried running the engine again for about 20 seconds more. Same result.

Notable? I did not hear the loud noise during this test, but I did not step on the accelerator at any point either.

RonD, I think you are telling me that if the fan clutch is stuck, it is stuck engaged to the fan, meaning that the fan will spin even at times when it doesn't need to, or possibly all the time.

So your hypothesis about a stuck (or sticky) fan clutch might be correct.

But is it the spinning fan that makes that noise? It doesn't seem so, and that's the part I don't get.

 

Sorry, you're right again. They said compressor and compressor clutch. Never mind. My bad.

 

Yes, it reads like fan clutch is bad

The fan always spins when engine is running, it just not always pulling in air thru radiator, unlocked

Fan clutch looks like this: https://m.media-amazon.com/images/I/71EC+n7C5gL.jpg

The black part threads onto the water pump's shaft, it always spins at water pump pulley speed
The silver part has the oil inside, that's the "clutch" part
The fan blade bolts to the silver part, the 4 holes you see

The silver part can spin freely once the oil has thinned out, 40seconds is enough time for that to happen

Front of fan clutch seen here: https://m.media-amazon.com/images/I/81aAyzEk6vL.jpg
Thats the spring that is heated up by the center of the radiator, and closes valve to lock the fan

Just a heads up
The 3.0l engine uses Reverse Threads on the fan clutch to water pump nut
Should say that on the shroud

So instead of "lefty loosey, righty tighty" its righty loosey, lefty tighty, lol
So opposite/reverse thread

 

Thank you RonD! fyi, just a few minutes ago, just messin' after doing this test, I noticed something very concerning. I opened a new thread for it, because it seemed unrelated to this thread.

But in case there's a connection that should be noted... https://www.ranger-forums.com/genera...related-172719

 

RonD, My antivirus software says the two URLs in your post (with the images) are unsafe. Any idea why that is? Any alternate way for me to get to those images? I think they would be very helpful to see. Thanks.

 

Google: 2007 Ford Ranger fan clutch images

Click on the first link, "Images for 2007 Ford Ranger fan clutch"

Links are fine they are just to parts sellers on Amazon

Add the word "images" to any search to see what a part looks like

 

Oddly, just now I clicked on both links again and they worked fine. Not sure why I got all the warnings before..... Technology, I tell ya'! ...lol...

 

My truck has been getting very poor MPG (around 13-15), and seems underpowered at times. Previously the mechanic said he detected misfires on multiple cylinders.

I asked him to change out the plugs and wires, thinking this would help.

It still might; I only got the car back a couple days ago and haven't even driven it much since then.

But now I wonder if this could have been the problem the whole time.......

RonD, thanks again, you've been VERY helpful and have given very good explanations to a guy who is logical and can read and knows some basic physics, but knows almost nothing about cars. Hence, not totally clueless, but half-a-clue-short...... Thanks!

 

I doubt very much if misfires would make the sound you described

You should get a Bluetooth OBD2 code reader, under $15, had an ELM327 for many years and it still works, but needed to read transmission codes so got a BlueDriver about 3 years ago, no complaints except $100 price, lol, I am cheap

In any case, these use your phone or tablet as the display screen, APPs are free or $5
You can read and Clear codes but ALSO watch LIVE DATA as the computer sees it, so you can see if a sensor is out of range or not working at all
Sensors are expensive and people often just replace them
OBD2 code reader is WAY cheaper, right up there with a volt meter and vacuum gauge

 

Thanks for the suggestion about the OBD2 code reader.

To clarify, I meant that the misfires might have contributed to the low MPG and iffy power, not that they were causing this noise, which I hadn't related to any other issue until now.

I think now that the fan clutch might not just be causing the noise, but causing the low performance and low gas mileage as well. That's what I meant to say.