1998 Explorer Chirp - 4.0 SOHC

[tyler.darby]

My 1998 v6 4.0 SOHC has been chirping awfully for over a year now. It seems to be worst in the colder months.

Right now, as soon as the car starts the chirping starts, very loud, frequency increases as RPMs increase.

At one point it went away when the engine heated up but now it just gets a little better, never goes away completely.

When we spray the belt with water, it stops until the water dries, then starts again.

We have replaced:

• Alternator
• Belt
• Tensioner Pulley
• Idler pulley

Belt dressings make it worse. It went away almost completely in the summer when things were warmer.

 

[swshawaii]

Harmonic balancer (Crankshaft pulley) checked?

4.0 Harmonic Balancer - know when it's going bad & how to fix | Ford Explorer and Ford Ranger Forums - Serious Explorations

 

[tyler.darby]

Took the car to a mechanic (who couldn't fix the problem) but asked about the harmonic balancer and they seemed certain it wasn't the issue. Might check for myself though.

 

[swshawaii]

Did you check ALL the pulleys for binding with the belt removed? Also run the cold engine without the belt for less than one minute and
listen for internal engine noise. Camshaft position sensor? One thing many fail to do when the belt is removed is clean the belt and all
pulley grooves. Use a small stiff nylon brush with dish soap and water and scrub away. Amazing what rinses out after almost 20 years.

Too late now, but just FYI in the future:
Why Belt Dressing Is Not a Solution To Quiet a Noisy Belt
www.daycoproducts.com

 

[tyler.darby]

Did you check ALL the pulleys for binding with the belt removed? Also run the cold engine without the belt for less than one minute and
listen for internal engine noise. Camshaft position sensor? One thing many fail to do when the belt is removed is clean the belt and all pulley grooves. Use a small stiff nylon brush with dish soap and water and scrub away. Amazing what rinses out after almost 20 years.

Too late now, but just FYI in the future:
Why Belt Dressing Is Not a Solution To Quiet a Noisy Belt

One thing I should add, we can soak a paper towel in water and touch it to the FLAT (non-grooved) side of the belt while the engine is running, and the chirp stops. Strange behavior which leads me to believe that it is the result of the idler pulley (which we replaced) or the water pump, since those are the only two that touch the belt on the non-grooved side.

Also, we added belt dressing, it made it worse.

 

[swshawaii]

Also, did you replace only the tensioner pulley or the complete tensioner?

Worn or broken tensioner springs are quite common and can cause many issues.

Check the Signs of Belt Tensioner Failure and the videos in the link below.

http://www.rockauto.com/en/moreinfo.php?pk=3674&cc=1304413&jsn=434&jsn=434

 

[Josh P]

Fan clutch would be my guess, I think sohc fan clutch will draw more air as it fails putting more load on the belt than it can handle. I swapped the sohc fan clutch onto my aerostar and have had 3 fan clutches fail. the belt would squeal from the fan not being able to keep up with the rate of acceleration of the engine. I replaced the fan clutch and the squeal went away.