I read past post about this but was wondering if anyone else has this problem and what they did to correct it.

I have a 2001 7.3 225000 miles.
Only under a load does it whistle or squeal so loud it makes you want to pull over. It happens when the truck down shifts at a hill or to pass but as soon as you let off the accelerator it quits and it mostly happens in warm to hot weather and the fan clutch seems to cycle alot at this time. When I pull my camper at night it does not seem to happen as often in the cooler night air. Im not sure if the fan clutch could be causing this problem.

If anyone could give me some info I would appreciate it, I"m getting ready to leave on vacation and pulling my camper I would love to have this taken care of before I left. Thanks
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yup, sounds to me your fan clutch is working the way it should.

 

Mine kicks in during hotter weather since I am usually running the A/C but... Mine just sounds like rushing air. No squealing or whistle. The only thing I hear other than that when under load is the whine of the turbo.
If yours is definately making squealing noises...Yeah I would have that fan clutch checked out.

 

Thanks for the quick replies. It's def not the turbo whistle. It reminds me of a steam kettle on a stove blowing off.

 

A squeal is usually the serp belt slipping. The serp belt might be slipping when the fan clutch engages when there is more of a load on the pulley. Or the belt tensioner is getting weak and not holding the belt tight. When it is cooler the fan clutch just isn't engaging as often and is why it seems better at night. A new belt would be a good start.

 

If you change out the belt and haven't did the upper rad hose for 2 alternaters now is the time to do it.

 

I changed the belt and tensioner about 6 months ago. On another forum someone suggested changing belt, tensioner and water pump pulley. I never heard of changing water pump pulley??? Has anyone else? Could it be a leak on the turbo? Or would that leak all the time not just under a load?

 

Do you have a boost gauge, i have heard a boost leak whistle before. On my truck i had a squeal that I could not find that only happened at higher rpms, aka above 2500rpms and above, turns out it was the tensioner , it made it self easy to find when it came apart and tossed the belt.

 

I will replace the tensioner and give it a try. This time I will go with OEM. I replaced the last one with Auto Zone brand. If that fails I will make a video of my truck pulling and maybe someone will reconize the sound.

 

Check for boost leak. A small leak under higher pressure can whistle. Its worth a shot.

 

JJD - Please let me know how that works for you - I am having same problem under load when towing & fan pulls in - Very loud high pitch squeal. - I have new boots in the garage just waiting for some cooler weather to get them installed. Thanks - Does anybody know if fan clutch bearings would have side to side play in them if going bad ?

 

wrong button

 

I'm kind of new to the diesel world what is the best way to check for a boost leak without a gauge. To me it sounds more like an air whistle than a belt squeal so this maybe the problem. Guitarpicr we are from the same location STL, MO. I will post what I find.

 

The best way to ck for boost leaks is to buy a 3 in pvc end cap, install a quick disconnect adaptor for your air compressor hose to hook up to it and disconnect the intake hose from the air filter and install the cap there and apply 10 - 15 psi and put soapy water all over where your boots connect.

 

Thanks I will do just that.