Strange Engine Bay Sound on My Gen 2

[brfails]

Alternator charging?

Would that indicate a failing alternator?

 

[New recaros]

Would that indicate a failing alternator?

I was just saying if your alternator is going out, they tend to start making noise before total failure. Maybe every time it goes to full load/charge it starts making noise. The fans others have mentioned may be it.

 

[FordTechOne]

It sounds like the cooling fans are running. Which is normal operation.

 

[New recaros]

It sounds like the cooling fans are running. Which is normal operation.

I agree to fan noise, but why is it cycling. It sounds to me like the fans are in surge, something blocking flow or voltage swings that change fan speeds. Should it not be a constant sound?

 

[FordTechOne]

I agree to fan noise, but why is it cycling. It sounds to me like the fans are in surge, something blocking flow or voltage swings that change fan speeds. Should it not be a constant sound?

I thought that was just the way the recording was picking up the sound, but yes surging wouldn’t be normal.

 

[New recaros]

I thought that was just the way the recording was picking up the sound, but yes surging wouldn’t be normal.

Are those fans variable speed or all or nothing?

 

[smurfslayer]

Def. a fan. Have you been off road? I heard a very, very similar noise in my Raptor Assault truck back in 2017. the fans can collect mud on them, loads them more and creates an out of balance condition.

 

[FordTechOne]

Are those fans variable speed or all or nothing?

Raptors use brushless fans that are variable speed controlled by the PCM.

 

[New recaros]

Raptors use brushless fans that are variable speed controlled by the PCM.

To me, it sounds like the fans are varying in speed so a tuning or control issue. Maybe the thermocouple wiring or what ever they use to sense temp. If it’s a tunable point, less gain and longer reset. Can you monitor the PCM input and output to the fans?

 

[Enersol]

This is wonderful. Mine 2020 just started doing this same sound right after offroading and going through deep boggy mud. I had quite a bit of mud trapped ontop of the skid plate that I cleaned off but I did not squirt the fans well enough. Mine only makes the sound when its at idle and with this 100 degree temps it does it all the time now. Makes perfect sense now. Thanks for the video.