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Replacing my cooling system, should I do the harmonic balancer while I'm in there?


NAXJA Forum User
Northern CA
What's the lifespan of a harmonic balancer on an xj? Mine is a 99 and it has the original and the rubber is cracked but other than that I don't see any problems. Well I have the radiator out and some room should I be doing my harmonic balancer or can these last a lifetime of the vehicle?

My 99 shot it's wad at about 180k.... My 96 has close to 400k and I know it hasn't been changed since I bought it at 178k..
I will say I didn't need any additional room. It was an easy swap to do with everything intact.

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I replaced the harmonic balancer on my 98 with about 215 thousand miles on it I did remove the stock front bumper .
I have replaced the one on my '96 and the one on the '97 ZJ that Varmint #1 drives. In both cases I chose to replace them because I was already removing them in order to deal with the front crank seal and the timing cover gasket.

I don't think I would have opted to replace them as a matter of water pump scope creep. I have not noticed an abundance of threads involving dampener failures.
Its a $50 part. I did have one go. Not good. Also, I'd think about a new timing chain set and replacing the seal. I did replace one recently on a 2000 with 260K. I did use a NAPA timing chain. it didn't seem any better than what I replaced. Possibly the gears were worn.
With the cracks in the one shown, I'd replace the harmonic balancer. Again, $50. Replacing the crankshaft and bearings, a bit more.
Mine came apart on my 98 at 140,000 miles. Luckily, I was backing out of my garage when I heard a weird noise and it got hard to steer. When I pulled back in and had a look, the serpentine belt was just sitting there loose. Looked harder and saw that the balancer was now two pieces. So glad that it didn't happen on the highway or at serious revs.

I have a front skid plate with a tow bar on top of that. To remove the tow bar, I have to remove the bumper.

I saved a couple of steps by removing just the bumper and doing the work from there. Not easy but could have been worse.

I would say, do it while it is easy.