if anyone's interested here's how i changed out the tensioner assembly. it was easy.

1)unclip air cleaner and push intake tube towards rear of engine bay out of the way.
put adjustable wrench over top of old tensioner and use a pipe over it to pull tension away (towards right side of vehicle)from serp belt. some tensioners may require you to put a regular socket wrench (without a socket on it!) or breaker bar onto the front of the tensioner to release the tension. mine did not. release serp belt from tensioner pulley

2) unscrew bolt in the body of the tensioner. mine was 13mm. you can again use a pipe over the socket wrench for more torque. remove old tensioner

3) installation is reverse of removal. my new tensioner had a different size bolt than the original one.
there is an indent on the engine side to match up with the new tensioner so you can't position the tensioner off kilter.

i did this whole operation from the top and it took about 15 minutes including repositioning the serp. belt.

 

lol, now it got colder here.. 15-20 deg F , and the whistle stopped...

 

it came back again....

took off the idler pully (pretty easy) after loosening the tension on the serp belt.

pried off the back grease seal of the bearing...and lo and behold.. it was completely dry the ball bearings inside looked ok so re-packed with grease, put everything back together... noise gone.

 

That's great to hear you fixed it. Sometimes those things can drive you crazy for months without ever figuring them out!

 

Hah! I was trying to remember where my idler pulley was located (different from the tensioner on many vehicles) and the I realized that my motor doesn't have one! If you are lucky enough to have a non-power steering, non-AC optionless truck like mine, you too are exempt from that particular problem, although there are plenty of others to think about!

 

bah it came back again.. i put on a new idler pulley ...no change = now i'm back to square one...
it's definitely coming form the front of the engine...

 

I'm just throwing out ideas but perhaps your timing belt tensioner? If you engine has a similar arrangement to my 2.3L 4 cyl. there is a pulley there that could do it.

 

yeah maybe i'm not sure if it ever got changed. it's not the a/c compressor because it has no a/c! i think i'm down to waterpump/timing belt/fan clutch...
the alternator pully spins smooth with the belt off..

just thinking out loud here ... = (grasping at straws...)

 

I've got a 97' 2.3L 5spd with 203000 miles on it. I bought it a year and a half ago with 170000 miles. I have had the same whistle. I have had the throttle body and intake off. After pulling the intake apart I still couldn't find any leaks or anything. But I have had the throttle body off a few times. After removing it and re-installing it, each time the pitch changed a little. I do have one question though. Have you done any engine work to it or is it still the original head and all? If it is do you have a missing problem withit if you get the rpm's above three grand or so when the engine is cold?

 

ok 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

 

good thought, and i eliminated that by starting the engine cold, without the serp belt on.

 

the old alt. sat on my bench since i took it off the engine and within one week it was totally seized. took it apart. dry bearings... and almost toasted brushes. bye bye to the dump it went...lol

 

(https://www.ranger-forums.com/4-0l-o...rottle-146135/)