I think there's a wind tunnel under my hood!

[BootyDo]

Hello,

Ever since the weather warmed up here, my poor truck has been howling. A few weeks ago, it sounds like it was a diesel or UPS freight truck. Someone mentioned it was my fan spinning too quickly in low gears or something. So I began listening and trying to find a pattern. So far, have this:

When I first start the truck, just fine. After a bit of driving, (say 5 minutes), the fan (?) will come when accelerating after the next stoplight. Stays on and the truck is sluggish until 3rd gear or so. Next stop, it continues. If I turn the truck off and then back on, the fan (?) will operate normally again after first hitting 3rd gear once more.

Does anyone know if this is really something with my fan, fan clutch, or something else entirely? I can spin my fan freely by hand if that's good or bad...

TIA!

 

[TestPoint]

My first suggestion is to replace your thermostat.

The engine may be having a fit trying to keep itself cool.

 

[BootyDo]

Thanks TP! I was wondering if that was the culprit, but the only thing is that the engine itself isn't running hot, (luckily for me!). I took the truck out this weekend and think I found the symptoms, (as opposed to randomly occuring):

When I start the car and allow it to warm up, it's fine. When the operating temperature officially hits "normal" (midway on the temperature gauge), the fan will run like crazy following the next stop longer than 30 seconds.
If I turn the car off after the symptoms appear and then restart it, the fan will return to normal operation once I reach at least 3rd gear.

Just shooting in the dark, but does this sound more like a sensor thing?

 

[TestPoint]

Do you have electric fan(s) or a viscous clutch water pump mounted fan? My car is the previous series from yours so I am guessing.

If it is the viscous design I will stick with my initial thought of thermostat no matter what your gauge says.

If electric then you can get into sensors.

Does sound heat related though.

 

[BootyDo]

Aaah - great point! Honestly, I'm not sure what this would be. Is there a way I can tell on a 2006 V8 Limited, (not sure if the V8 would differ from the V6 or if it's entirely general, but the idea anyway).

Also, I think you're spot on about it being heat-related. It seems like once the weather reached the high 70s/ low 80s, this became an issue. Now coincidentally, it's been muggy the past two days and it hasn't triggered the excessive blowing. Might just be coincidence more than anything but...