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harmonic balancer


NAXJA Forum User
Ok- I had my truck in the dealer shop last year (before I found this site- ack) and among the many recommendations they gave me, they said my harmonic balancer was toast. I'm not really sure was an HB is, what is does and looks like, what the symptoms of its failing are, and if changing it out is something I can do. Any help for a rookie- thanks...
It's that round thing on the front end of the crankshaft, the bottom pulley that the fan belt goes around. The usual symptoms are (a) you can see a ring of rubber beginning to stick out from where the outer metal ring fits over the center hub; and (b) your engine starts eating fan belts like a fat kid on Halloween night.
Had to replace my harmonic balancer last month. Like Eagle said it was eating up belts. I am also a rookie and changed it out in an afternoon. The rubber part was toast, allowing the pully to move forward, making the belt jump out of the grooves and tearing up the belt. if you change the hb it might not be a bad idea to put on a new belt.
If you do it yourself, make sure you heatup the balancer by boiling it, or putting it in the oven before you try to press it on. Don't use the bolt, to draw it in, use a wood block and a BFH.
BrokenXJ said:
If you do it yourself, make sure you heatup the balancer by boiling it, or putting it in the oven before you try to press it on. Don't use the bolt, to draw it in, use a wood block and a BFH.
1. You can also 'shrink' the crank snout by packing it in ice for a couple hours prior.
Do the operation pretty quickly, before the two materials transfer heat and equalize in temperature/size.
2. You can get a longer bolt of the same thread, with a matching nut. FULLY seat the bolt for complete thread engagement, then use the nut to draw the balancer on. Replace with proper bolt.
3. Coat the snout and 'adhere' the Woodruff key with a bit of assembly lube like STP.
You might want to do that ASAP, I had a 454 in a dually where the ring that was isolated by the rubber came off on a trip to Rocky Point Messico, I was towing a sandrail on a trailer in back. I had to drive the rail 20 miles on I-8 to get to Gila Bend to buy a new harmonic balancer, then install it on the side of the highway. Not a cop in sight!
Make sure that you take your old one in and check it against the new one. I found out the hard way the the 4 banger 2.5 HB is very similar to the 4.0 HB, with one very important difference. The collar on the 4.0 HB is a little longer. I went to Autozone and bought a new HB for my 4.0 and installed it. Everything went well except for this contact noise that I was hearing. It was very light and was not really bothersome, but after investigation, I could see where the HB was rubbing on the timing cover. It by this time nearly worn a groove through it. I went back to Autozone and this time compared the two and the 4.0 collar on the HB is longer allowing it to have clearance between the back of the HB and the timing cover. Not a big problem, but just a little headache in mehcanical work. Hope this helps,

Warning! Am I the only one that saw this? Do not heat the Balancer in an oven. And I would not boil it either. There is a Rubber ring in there that will melt. I put mine in the dash on my truck for a few hours. I could not touch it when I started the instal.
Good call Ghost! I was able to get mine on without any tricks (I was in the parking garage of my work) with heating and the like, you just have to be patient. I found that it helped a lot to remove my front bumper to do the work, there's an access hole in the radiator support that works wonderfully.

The bolt in the center is going to be on very, very, very, very, very tight. I used a 10" crecent wrench to block the balancer from turning to remove it.

Also, as was said, do it now, mine flew apart (the outer ring flew off) on the freeway, luckily it didn't do any damage by parts flying, but it did end up running without an alternator, power steering, or water pump.