squeal, chirp, whistle under the hood

[wolfdog2rags]

All-

A while back there was a thread called 'whistle under the hood'. There were also a couple of other threads dealing with the same described symptoms.

I have been searching throughout various threads but never found results on a fix. Has anyone come up with a solution yet?

I have many of the same symptoms listed in the 'whistle under the hood thread' and have done the following to try to fix them.........

sprayed/cleaned throttle body
replaced tension pulley
replaced idler pulley
replaced fan belt
listened to bearings in water pump, alternator, other parts with bearings.

Our noise, 'chirp' or 'squeal' only happens when it's cool outside upon startup/warmup and then goes away within a couple of minutes.

Sure would like to fix this annoyance!
Thanks for your help!

Brandon.

 

[TPLYNCH]

What year is your Explorer? Does it the sound while stopped, or only when you start moving?

 

[wolfdog2rags]

TPLYNCH-

It's a 1994, 4-door, 4X4, XLT.

It makes the noise while idling, immediatley after startup. During the summer months, the average temp has been around 85 degrees. The noise will go away within about 1 minute while the engine warms up.

In the winter months, 40 degrees and below, it will continue to make the noise while we drive until something warms up.......it then goes away after about 5-10 minutes of the engine running/driving.

Thanks!

 

[kilroy]

Bad belt. Rubber shrinks when it heats up, so it is loose when cold, and after it warms up it gets tight. Could also be a bad tensioner.

 

[kilroy]

OOPs

I didn't read yours all the way through, you already replaced that stuff. Could be the power steering pump. Try flushing the fluid out of it.

 

[pistol_fish]

Only true possibility I've found

The only logical explanation I have found that wasn't invalidated by other posts is thos one "The whistle is from the air bleed hole in the throttle plate...extra airflow makes it whistle when under very light accel."

This would explain why at idle it's not audible or very slight (too little air flow), and why during hard acceleration it's not noticable (too much air flow to whistle). Under light acceleration you have just the right amount of air flow to whistle, a little more gives a lower whistle and a little less produces a higher pitch.

 

[wolfdog2rags]

Thanks pistol_fish.