I have a '04 150 4X4 with the 5.4L with almost 50K miles. It has been an outstanding truck, but lately it's been making a strange noise when I step on it. If I accelerate gently, it sounds completely normal. But if I step on it, it starts to growl very loudly. It's never done anything like this before. Any ideas whats up?

 

Need to know a little more on the status of the truck when it does it. Is it warm or at cold start? Is this at a stop light? What are your A/C settings?

There are a lot of "armchair mechanics" here as well as a great number of certified mechanics. I'm sure we can all get to the bottom of this if you specify a few more details.

Good luck. We're here to help youl

 

Great! thanks!

It occurs when the engine is warm. It might happen just after I firts start it too, but I always drive easy for the first couple of minutes. It'll happen any time I step on it. From a stop, up a hill, or accelerating to pass another vehicle. And by "step on it" I mean press the accelerator harder than usual. I can drive it easy all day and the noise never happens. There is no other symptom at this time - Even when it's making the noise, everything else feels perfectly normal.

 

Armchair here, but I think the first thing I would do is pull the transmission dipstick and look for clean pinkish fluid and smell. Should smell like trans fluid. Do have any idea where the noise is coming from?

 

Heh heh heh. What's trans fluid supposed to smell like....chicken?

Seriously, trans fluid shouldn't smell burned at all so Armchair is starting to point you in the right direction.

 

Yea Is it coming from the front, middle or back?

 

Well, the tranny fluid is nice & pink, and full. And the sound is coming from the engine compartment. Just a thought, but it started just after I had the oil changed. I'm not a mechanic, but could they have gotten oil on one of the belts or something? My old '88 150 had a serpentine belt, not sure about the '04. But could that be slipping & causing the noise?

 

It's possible there could be oil on the belt but it would sequel like it was slipping instead of the noise you're describing. Check and see if the oil filler cap is there. It is possible they forgot to reinstall which could cause some noise. Yes, it has a serpentine belt. Also check the air box where the filter is and make sure it's in place and tabs are locked. They love to sell new air filters. I'm trying to think why a noise would occur after a oil/filter service. Check fluid level in power steering reservoir also. Other than that, I can't think of anything that would cause that noise after a service unless the tech left something loose. Hope you can isolate the noise and get it fixed.

Edit: My 04 made that noise a couple times and I found that the snorkel that snaps into the pass fender well came out and caused a heck of a noise. So I just pushed it/snapped it back in place and the noise was gone.

 

It is possible you are losing vacuum to the front IWE's (hubs). Default position without vacuum is the hubs are locked.

 

I agree with KingFish - I put on a leveling kit last weekend and afterward had the same noise (I think) with the same symptoms. Look at the pair of vacuum lines that go into your front hubs. My noise was coming from the front passenger side so thats where I started looking. I saw nothing abnormal there. Then I looked at the drivers side and the hoses had been sheared off their spigots on the hub. Easy enough fix - I cut about a quarter inch off the tubes and slid them back on. No noise now.

 

I had the growl sound on my FX4 2003 turned out to be the fan clutch..

 

would it do it all all temperatures? my truck makes a growling sound only while the truck is cold and only at the colder times of the year.

 

Yes it will do it all temps I had the same problem with my truck a few months ago. I had mine fixed at the dealer and have not had a problem since. One way to see if its the IWE is to put it into four wheel drive when you hear it if it goes away you found your problem.