harmonic balancer. Go check yours!! right now!

[Pete M]

so I noticed that the HB was suuuuuper close to the timing cover and so I stuck a 5way in there and I can pry and cause the  HB to move forward.  this is a bad thing, right?  time for a new one?  the rubber thingie seems to be falling apart.  I'm going to put a new one in. 

 

 

[Ωhm]

3 minutes ago, Pete M said:

this is a bad thing, right?

 

That is the correct symptom for this: Bad Thing.

[oleskool]

Just did this myself 😂 to be fair I’ve known it needed to be replaced since I pulled the truck out of a barn 2 years ago 🤦‍♂️. I waited until it started making a knocking noise at 2k RPM to do anything about it 😳

[schardein]

A couple years ago I started my XJ and heard a slight “tinging” noise. Upon investigation, part of the rubber between the inner and outer shell of the HB was sticking out, hitting the mechanical engine fan. Replaced the HB and all was well. 

[pizzaman09]

I changed mine a few months ago.  I am embarrassed to admit that I had a heck of a time getting it off with the puller.  Turns out the big giant 1/4" thick washer on the front was stuck to it and I was trying to pull the balancer through that washer.  Once the washer was removed it came right off!  

I suspect mine was not original as it was still decent at 250k miles on it.

[75sv1]

I've added that to my list of parts to change a few years back. On my '98 XJ, I didn't catch it in time. Took out the flange on the crankshaft. 

[gogmorgo]

Had one go on me, just had a wobble but it was enough to slap the belt against the timing cover, making an annoying chirp. Somehow the belt was winning the fight, too. Nice little groove cut in the cover. 

[AZJeff]

It's pretty well known on all the various Jeep forums that the 4.0 harmonic balancer has this tendency to separate in such a way that the outer "pulley" portion walks in or out from the "hub" portion.   I don't know if it's a poor choice of rubber materials, or something related to the design, or both.

 

I remember reading a story on one of the XJ forums about a guy who had his balancer fail in such a way that the pulley portion walked off the FRONT of the hub, fell out on the ground, and since it was spinning at idle (the vehicle was stationary, it scooted across the parking lot and slammed into another vehicle, causing a bunch of body damage.

[75sv1]

Some of it is the newest XJ is over 20 years old. Rubber does deteriorate. When I first bought my 81 MB 240D, I had to replace all the belts and hoses.  The hoses looked like the pictures in a Chilton manual.  Also, I've had radiator caps go bad. 

[AZJeff]

2 hours ago, 75sv1 said:

Some of it is the newest XJ is over 20 years old. Rubber does deteriorate. When I first bought my 81 MB 240D, I had to replace all the belts and hoses.  The hoses looked like the pictures in a Chilton manual.  Also, I've had radiator caps go bad. 

I live near PHX.   Out here, rubber drying up and cracking is a way of life due to the heat and the UV rays in the sunlight.

 

The wife's KJ Liberty is 19 years old.  Even though it had just about 100K miles on it at the time, I had to go through and replace all of the suspension bushings due to "dry rot"

 

And don't even THINK about what it does to all the plastic clips and retainers on cars nowadays.   Each time I remove one to do some sort of repair, I say a little prayer before I try to pop them off

[gvthnks]

Mine separated in my 99 XJ a few years back.   I only knew it because when it started the outer shell moved forward toward the radiator and it threw the belt.  I didn't really hear it, but the AC stopped, the alternator stopped, power steering stopped.     I was fortunate to be about 2 miles from my house so I just drove it home.  

[gogmorgo]

Plastic gets brittle with age even without the UV exposure. But it definitely doesn’t help anything. It also gets incredibly brittle in cold weather. If you’re ever doing anything under the hood on a cold engine at -40 (hope no one else ever needs to experience that) things just shatter on you. 

[camo89]

I also lost one probably 8 years ago now. It just spun on the rubber. I was 30 miles up in the snow and no power steering was how I first noticed. Had to get a buddy to deliver one and change it in the snow.

[Tex06]

On 6/30/2023 at 10:19 AM, gogmorgo said:

Plastic gets brittle with age even without the UV exposure. But it definitely doesn’t help anything. It also gets incredibly brittle in cold weather. If you’re ever doing anything under the hood on a cold engine at -40 (hope no one else ever needs to experience that) things just shatter on you. 

Oof. That's some serious Bristol Bay vibes for sure. 

 

We drain the oil after fishing season. Why? B/c it'll freeze in the block and crack it if you don't.