Hey all. I was driving for about 1hr yesterday in some hot weather with the AC on and driving up hills. The truck got a really loud hum or growl to it while I was driving after about 1/2hr when I would give it gas, especially from a stoplight. Kind of scary sounds like it is going to blow.I have a K&N, could that be the issue, or is this common?
I turned the AC off and it still did it. This morning it was fine. It has happened before in the summer heat but usually dies down after driving it for awhile, this time it didn't stop.
It is a really annoying humming, can't really describe the sound that well. It sounds a little like when you stay in one gear way to long but constant doesn't get louder as time goes by. I believe it has something to do with the filter or the intake. My intake is stock exhaust for the K&N and I know it's not the tranny. MAF or the IAC maybe? IAC was just replaced.
Any opinions?

No CEL and no performance problems.

 

I've seen this at IDLE in the summer due to a dirty IAC valve. Cleaning it usually fixes it. I call the Ford 4 Liter Moose Call.

 

I read the moose call saying on here before, just couldn't remember what it was until you just reminded me of it. I'll check it out tonight. Thanks!

 

IAC can make that noise. And are you sure it's not the fan clutch locked up making the fan louder?

Rich

 

Definitely sounds like IAC to me, easy fix!

 

I believe the fan clutch would lock up and cause the noise constantly. Once I'm up to speed and driving along the sound dies down.

 

It's the fan cooling down the engine when you are stopped for a while it's normal. It stops once you get going and air blows through the radiator.

 

I am not sure about that. It gats really darn loud and doesn't sound like the fan. Would it get louder as I gave it more gas.

 

That would be the IAC making the humming sound i believe.. it's common on the 4.0L OHV's

 

Quote:
hot weather with the AC on and driving up hills

Extra load on the engine = extra heat generated.
That sound is the fan clutch doing it's job.Turning the fan to cool the engine.

Also with cold weather , 10 degrees and lower ,If you were to start the truck cold and drive off , The clutch will hang for a few seconds to a minute or so.That is normal.

 

yes, it gets louder because it will spin it faster as the rpms go up. it sounds like a bunch of air being sucked in.

 

clean your air filter

 

Did that last night just to make sure. Then I realized I had no filter oil. So I'm driving around now without any oil on the filter.