How to: 4.0 Harmonic Balancer - know when it's going bad & how to fix

MODS, please "sticky" this thread...

I have searched this site and have included the pertinent 4.0 harmonic balancer threads into this one, to make it easier for future reference and to help those who are seeking the proper information regarding the 4.0 balancer issues.


This is a very problematic issue w/ the 4.0 Explorers (as well as the 4.0 Sport Tracs).

The first signs of a 4.0 balancer starting to fail - distinct "chirping or squealing" of which resembles a serpentine belt squeal. At idle, the noise will resemble a "chirp", however, when driving, the noise will progressively get louder as RPM's increase and will turn into a loud pitched squealing, slowing down again when coming to a stop. The noise will be coming directly from the balancer if positioned under the vehicle while listening at idle. IF the serpentine belt is removed, the balancer will not squeal or chirp, it will only do it w/ the belt on and under tension. If all other front end accessory pulleys do not make ANY noises when manually spun (w/ engine & belt OFF), the harmonic balancer is the problem.

Besides the obvious chirping/squealing, other ways to detect a failing 4.0 harmonic balancer:

1) watch the serpentine belt & belt tensioner @ idle - if the belt is not following a smooth path while running and the belt tensioner is sporadically "jumping or bobbing", it's a bad balancer

2) if while watching the serpentine belt @ idle and looking down at the balancer, if you see ANY slight wobbling of the balancer, any run-out or that it's not tracking straight, it's a bad balancer

3) with the serpentine belt off, if you tug on the front of the balancer pulley and the OUTER ribbed pulley moves even slightly, can be wobbled back and forth (side to side) or in some instances will pull/slide forward (towards radiator) or can be pushed backwards (towards engine), it's a bad balancer

4) if the bonded rubber elastomeric center that secures the outer ribbed crank pulley to the center of the balancer is either protruding (not flush w/ the face of the metal pulley) OR there are visible signs of dry rotting/cracking/deterioration, it's a bad balancer

5) IF the serpentine belt is NOT on the RIBBED section of the crank/balancer pulley and is in FRONT of it on what appears to be a smooth rubber surface, then the balancer has already separated and you should not be driving the vehicle.

Too many of us have had to replace this part - luckily some of us did not have extensive repair bills, while unfortunately other failures have resulted in more damages & extensive repair bills.

There is a revised 4.0 balancer (crank pulley) through Ford that is better and not like the original design.
The revised 4.0 harmonic balancer Ford part # is: 8L2Z-6B321-A

IF you take your vehicle to a Ford Dealer (or other shops) - do NOT let them tell you it's just a bad belt or other misc. pulley causing the chirp or squeal, especially after you have confirmed via steps 1-5 above that the source of your problem IS the balancer. You do not want to continue to drive a vehicle w/ a bad harmonic balancer as you will and can only cause more damages to other surrounding components or even worse, end up with possible engine damages - fix a bad balancer ASAP.

PICS & DISCUSSION OF FAILED BALANCER: http://www.explorerforum.com/forums/showthread.php?t=296853

MORE PICS & DISCUSSION OF FAILED BALANCER: http://www.explorerforum.com/forums/showthread.php?t=267709

MISC. BALANCER DISCUSSION: http://www.explorerforum.com/forums/showthread.php?t=299522&highlight=harmonic+balancer

MISC. BALANCER DISCUSSION: http://www.explorerforum.com/forums/showthread.php?p=2589015#post2589015

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If others have more to add to this thread, feel free to do so. It's important that other/all 4.0 Explorer and Sport Trac owners are aware of this common problem.

04-05 years have a weight/ring inside the pulley that becomes loose, you can feel it loose when you reach inside in the pulley itself and cant be seen.

thanks cobra... ill be getting that done next week to get rid of that damn chirp.

just wanted to know I have a loud knocking sound on my 2004 explorer so we thought it may have droped a valve so we took the valve covers off but it all looked ok...one of the valves wasnt closed so he went to turn the motor by hand and when he put his finger inside of the balancer i heard the knocking sound.We think that is the same sound.So I just wanted to know if this is possably my problem and if it has happen to anyone else....

Thank you for putting all this info together! Just wanted to chime in here. My 04 Ford Ranger 4.0L started chirping/squealing early last week. Was able to look at it on Saturday and found that the outer section of my harmonic balancer had separated from the rubber ring and slid back against the engine. The belt caught on the rubber and started wearing into it. At first I figured it to be tensioners going bad but I am glad I got this looked at soon enough and was lucky, from other horror stories I am seeing, the damage could have been pretty bad. $350 for a new balancer and labor to do the swap and all is well again.

my explorer is making a fart/grind type noise coming from that area of the engine and the belt bobs, could that be it? this is on the ohv 4.0.

So, the dealer where I bought my car new in 05 changed my belt about 1 year ago... About 1-2 weeks ago my belt started squeaking... It was worse when I pressed on the gas and went away at idle... I didn't read anything on the web at the time so I brought it back to the dealers shop and they said the belt had to be replaced. I had the belt replaced, and 110000 mile service, for $240. I drove to and from work two days and last night when I started the car the battery light came on, followed by the "service charging station" warning light. I soon discovered my power steering was gone too... I looked under the hood and discovered I had no belt. I had the car towed this morning to the dealers shop and I expected them to replace the belt and give me something for my troubles... To my surprise they called and said the harmonic balancer was the problem and they would give me free labor to install new one for $330. I told them it seems strange I never had a belt problem before and 2 days after they change the belt there is suddenly this problem...??? Does this make sense to anyone? Any comments? (I doubt anyone will see this before tomorrow morning but if you do, and you know something about this, your input is appreciated.)

jgdski said:

So, the dealer where I bought my car new in 05 changed my belt about 1 year ago... About 1-2 weeks ago my belt started squeaking... It was worse when I pressed on the gas and went away at idle... I didn't read anything on the web at the time so I brought it back to the dealers shop and they said the belt had to be replaced. I had the belt replaced, and 110000 mile service, for $240. I drove to and from work two days and last night when I started the car the battery light came on, followed by the "service charging station" warning light. I soon discovered my power steering was gone too... I looked under the hood and discovered I had no belt. I had the car towed this morning to the dealers shop and I expected them to replace the belt and give me something for my troubles... To my surprise they called and said the harmonic balancer was the problem and they would give me free labor to install new one for $330. I told them it seems strange I never had a belt problem before and 2 days after they change the belt there is suddenly this problem...??? Does this make sense to anyone? Any comments? (I doubt anyone will see this before tomorrow morning but if you do, and you know something about this, your input is appreciated.)

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your balancer was the problem all along, they will cause a squeaking noise that sounds just like a slipping belt, but it is the dampener from the section where the belt rides. sepearating.

jgdski said:

I didn't read anything on the web at the time so I brought it back to the dealers shop and they said the belt had to be replaced. I had the belt replaced, and 110000 mile service, for $240. I drove to and from work two days and last night when I started the car the battery light came on, followed by the "service charging station" warning light. I soon discovered my power steering was gone too... I looked under the hood and discovered I had no belt. I had the car towed this morning to the dealers shop and I expected them to replace the belt and give me something for my troubles... To my surprise they called and said the harmonic balancer was the problem and they would give me free labor to install new one for $330. <<<<<<<<<<<<<<

The dealership that changed your serpentine belt and charged you $240 parts and labor "ripped you off"! A new serpentine belt costs between $27-$40 for the V-6 engine. It takes 5 minutes to change, so at the most, they should have only charged you a half hour labor($35-$50) since they(repair shops) always round off the labor time on any job they do. Most you should have paid was around $90-$100 parts and labor. The mechanic at the dealership I bought my Ex at installed a new serpentine belt(Car Quest part) for me at no charge, parts or labor and installed it in 5 minutes while I waited for it. They even installed new fog lamps (Napa) for free. This was after I paid for the vehicle and had it in my possession for 2 weeks.

>>>>>>>>>>>>I told them it seems strange I never had a belt problem before and 2 days after they change the belt there is suddenly this problem...??? Does this make sense to anyone? Any comments? (I doubt anyone will see this before tomorrow morning but if you do, and you know something about this, your input is appreciated.)

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>>>>>>>>>>>

Either the mechanic is a scum bag and tampered with your vehicle trying to cause you other mechanical problems causing your new belt to break off, thus getting more repair $$$$$ work out of you, , or he is a complete idiot and installed the new belt wrong and never tested it by starting the engine to see how it is tracking on the pulleys. He may not have seated the new belt on the Harmonic Balancer pulley correctly and it snapped when you drove it later because it was off it's track. This may explain why he is offering you free labor to change the Harmonic Balancer, because he screwed up the first time and he's trying to cover his a$$. If I were you, take the vehicle to a different mechanic and don't tell them what the other guy charged you. Get a new quote and see if your Harmonic Balancer is really bad. This mechanic you went to sounds awful shady to me and his prices are outrageous.
FYI, I just checked out a price for an OE Harmonic Balancer from Advance Auto Parts, they want $160.00 for it and you can get $40 off that price ordering it online using an online coupon for their store. You could possibly find one cheaper online at some other parts outlet. So as far as your mechanic telling you he is going to do the labor for free on the Harmonic Balancer job, he is full of $hit! That price he gave you of $330 includes his labor charge. The guy is a crook.

Exproblems said:

>>>>>>>>>>>

Either the mechanic is a scum bag and tampered with your vehicle trying to cause you other mechanical problems causing your new belt to break off, thus getting more repair $$$$$ work out of you, , or he is a complete idiot and installed the new belt wrong and never tested it by starting the engine to see how it is tracking on the pulleys. He may not have seated the new belt on the Harmonic Balancer pulley correctly and it snapped when you drove it later because it was off it's track. This may explain why he is offering you free labor to change the Harmonic Balancer, because he screwed up the first time and he's trying to cover his a$$. If I were you, take the vehicle to a different mechanic and don't tell them what the other guy charged you. Get a new quote and see if your Harmonic Balancer is really bad. This mechanic you went to sounds awful shady to me and his prices are outrageous.
FYI, I just checked out a price for an OE Harmonic Balancer from Advance Auto Parts, they want $160.00 for it and you can get $40 off that price ordering it online using an online coupon for their store. You could possibly find one cheaper online at some other parts outlet. So as far as your mechanic telling you he is going to do the labor for free on the Harmonic Balancer job, he is full of $hit! That price he gave you of $330 includes his labor charge. The guy is a crook.

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Thank you VERY much for your time and your response. Yesterday the dealership service manager manager called and he told me the sensor and balancer needed to be replaced. He said the parts were $250 and he said he would charge me $125... After the sticker shock of $330 the previous day it seemed like I was getting quite a deal... I accepted the $125 offer but I will take your advice and stop bringing my car to the dealership for service... THANKS!!!

>>>>>>>>>>>

jgdski said:

Thank you VERY much for your time and your response. Yesterday the dealership service manager manager called and he told me the sensor and balancer needed to be replaced. He said the parts were $250 and he said he would charge me $125... After the sticker shock of $330 the previous day it seemed like I was getting quite a deal... I accepted the $125 offer but I will take your advice and stop bringing my car to the dealership for service... THANKS!!!

Click to expand...

>>>>>>>>>

The service manager at this dealership is now offering you a lower price ($125 for parts and labor) for the Harmonic Balancer repair that he previously quoted you at $330? Sounds like he is "guilty" of something. Is this a Ford dealership or a smaller, privately owned dealership/car lot? I'd still stay away from this guy and take it to some other repair shop, because he way over charged you for the first serpentine belt installation ($240 is ridiculous for a belt install) and since you never had a problem with the Harmonic Balancer prior to taking your vehicle to him, he is the one who probably damaged your Harmonic Balancer to begin with after he installed the serpentine belt on wrong, causing damage to it. I wouldn't let this guy get within 2 feet of my vehicle.

Well, I too have succumbed to the notorious failure that is this balancer. This is ridiculous. I have no idea how long the pulley has been like this or how it even ran at all. I am just glad I found it before it totally let loose while driving....






Grooves for the belt are nearly 100% smoothed

Removing the balancer crankshaft pulley

2002 Explorer with 4.0L ~105kmiles. Chirping noise, or belt squeek that is driving me crazy. Replaced all the idler pulley and tensioner pulley… replaced the alternator. Noise goes away when I run the truck without a belt. After some research… I think it must be the crank pulley/harmonic balancer – even though it looks fine? I’m going to go ahead and replace it. Can anyone tell me if I can pull the balancer/pulley without removing the fan and radiator? Looks pretty tight to get the thing pulled out? Thanks for the help.

On 2002 year we have had some problems with water pump pulley wearing and causing noise. You could try pulley and new belt.

water pump

when i had the belt off i turned the waterpump and it seemed smooth? You think it might be the water pump? or just the pulley? it looks fine, and the belt is new. maybe i didnt look at the pulley that close. i'll pull the belt back off and take a look. if that is the issue would it be obvious when looking at it?

crankshaft pulley

I looked at the water pump pulley, and it really looks fine. I dont think that is the issue. Fan clutch looks fine. I see some cracking or dry rot on the rubber between the harmonic balancer and the crankshaft pulley - so still think that is the issue. Anyone know if it can be pulled off without removing the fan and the radiator?

I'm going to replace the balancer on my '02 4.0L in the near future. I have read through several threads related to the balancer. It all looks pretty straight forward; Not unlike any other Ford product. What I seem to recall is a post somewhere, where a special tool is used to start the balancer onto the crank to pull it on far enough to pick up enough threads to bottom it out with the bolt.

Is it possible to work the balancer on by hand, far enough to use the (new) bolt or will I be doing some tool creation using the original (apparently, non-reusable, torque to yield) bolt along with some cutting and welding?

Anybody have any tricks (or advice) that they would like to share, so I can have my ducks in a row before I start?

Much appreciated.
Art

There is about an 1/8 inch difference on the length of snoult and where the bolt engages the threads of crankshaft. When you are pulling the old balancer you will run out of threads on bolt. I used a light hammer to finish sliding the old balancer off. When I was installing my new balancer I just kept tapping and checking to see if I could start the old bolt back into the crank threads. REMEMBER!!!! you can not let the crankshaft to rotate backward. I used crankshaft locking tool from my cam timing tool set to lock balancer while loosening the balancer bolt.. I used a chain wrench to hold balancer when torqueing the bolt.

scdix50 said:

..... REMEMBER!!!! you can not let the crankshaft to rotate backward. I used crankshaft locking tool from my cam timing tool set to lock balancer while loosening the balancer bolt.. I used a chain wrench to hold balancer when torqueing the bolt.

Click to expand...

I will heed your advice. I usually use a balancer holding tool of my own design (it uses the puller bolt holes) when removing/installing the bolt. I'll make sure that it is locked in a stationary position during installation.

So.... to sumarize.... It's really no different than doing a garden variety 5.0L (for example), other than you can not allow the crank to rotate backward.

I ordinarily dress the end of the crank, and an inch or so of the bore of the balancer with fine sandpaper and a light coat of oil to allow it to start onto the crank without undue pounding with a BFH. Sounds like the same routine.

I appreciate the input. Sounds like a piece of cake.
Regards,
Art

I have replaced the alternator, idler pulley and tensioner pulley in an effort to stop the ridiculous chirp i am hearing on my '04 X. I have checked the crank pulley for any wobble or looseness by hand and nothing moves. When I pulled the belt off, it had a slight stickiness to the crank pulley (I had sprayed belt dressing on it a few weeks prior). The chirp is only there in colder weather and when using the fan for heat or A/C when stopped. The crank pulley does show some signs of wear. Could it be that I just need to replace the pulley?