got a high pitched whistling/screaming noise coming from the front of the engine, but...

-only when it's cold out
-only at around 2600 rpms or thereabouts. at other rpm's the noise goes away..

it will do it while stopped or rolling.

have replaced the serp belt, tensioner and idler pully.
the intake tube looks tight and the engine doesn't seem to have any vac. leaks.

any thoughts?

 

AC clutch mabey ??

 

good thought but no a/c installed on this one.

 

Could be the alternator. My truck does the same thing when cold and that's where its coming from.

 

Sometimes water pumps start making that kind of noise when they start wearing out.

 

yeah when i had the serp belt off i spun the alternator and that seemed ok & the power steering pump had kind of a hitch in it .. it didn't spin smoothly... i blasted the shaft with wd-40 but it didn't seem to do much .. hmmm...
maybe the water pump is the next thing to check..

 

I was getting the same noise the other day when it cooled down outside. The more I listen, the more I think it is the speedometer cable?

 

if the noise increases or changes pitch when you rev the engine it's one of the pulleys, check all of them with someone revving the engine while you use a mechanic stethoscope

 

Most likely the Alternator. I had new bearings and thrust washer's put in mine (02 Sport Trac ) last year for this exact same problem, high pitched whistle only on cold days around freezing or below. The place that did it said the one bearing and thrust washer were shot and it was a were pretty common thing they see in this alternator. It fixed it. I believe it cost me around $50 w/labor. Better than a new $200 alternator.

In your case though, try to pinpoint the noise as it could be any of the pulleys as mentioned. I took my serp belt off and could feel a little bit of roughness in my alternator (not much) and I was about 95% sure the noise was coming from my alternator.

 

thanks for all the replies.
i think i'm gonna try to run the engine in the driveway for a short time w/out the serp belt on to try to eliminate the timing belt as the source...

 

arghh still can't track this down.. others having the same recently..
when the temp outside goes over 50 deg F it stops completely...

 

anyone know if autozone can spin an alternator at a specific rpm? the whistle only happens at around 2200 and 2600 rpms...

 

for those who pointed to the alternator...thanks that was it in the end.

went to a local pick n pull. found a 2000 ranger and yanked the alternator. the part (motorcraft )had a sticker on it saying it was built in '05... so it must have been a replacement. $25 .. dead cheap in my opinion.

long story short no more whistle!

the old alternator must have dry bearings.. when i got it off and spun it it was making a nasty kind of grinding sound.. maybe i'll take it apart some day...

by the way i did stick a multimeter on the battery .. the new alt. putting out juice nicely as it should
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ok i had left the old alternator on my bench since i took it out. went yesterday tried to spin it .. nothing! completely seized
took of the back off it and checked the bearing.. dry as a bone.
the brushes on the voltage regulator were almost toast as well..

anyway that was the outcome. hope it helps someone.

the old alt. is now scrap metal going to the dump, lol

 

My serp belt has screeched for 3 years now and my posts over that time reference that fact. It's always worst in cold, wet weather. I know it's the belt because just a small shot of Armor All sprayed while idling instantly stops the screech. Try that yourself or carefully reach under the moving belt with a wax candle for a second. You may be surprised.