Tonight we are going to take a look at what is involved in replacing the harmonic balancer on a V6 Commodore. Before we start we need to look at a couple of things, namely correctly diagnosing a faulty balancer and the tools needed to remove it.
So how do you know that you’re balancer is in need of replacement? The first hint is usually an intermittent metallic knocking noise from the front of the engine, typically worse at idle or when loading the drivebelt up with the aircon or power steering. At this stage a visual inspection will usually uncover cracked or missing rubber between the inner and outer of the balancer.
Make no mistake, if let go for too long damage can be done to things like the Crank Angle Sensor and the timing cover and you run the risk of loosing the drivebelt (and therefore drive to the waterpump, alternator, power steer pump etc) so don’t put replacement off once the knocking starts! Below is a short video demonstrating the typical noise that a stuffed balancer will make, although this one is extreme, the balancer was so close to letting go it’s not funny!
Tools You Will Need
As well as the basic tools (sockets, spanners, screwdrivers etc) you will also need a couple of not-so-common tools for this job. To loosen the bolt securing the balancer to the crank you will need a ½ inch drive 24mm socket and either an impact gun or ½ inch drive breaker bar.
Also if you have a VN Series 2 and onwards engine you will need a puller to remove the balancer. You will notice that there are three slots in the front of the balancer, the ‘correct’ pullers have either ¼ inch bolts that screw into threaded holes in behind these slots or fit directly into the slots, see pics below.
The pullers in the pics above are not all that common, we did quite a few of these back in the day so the expense was justified but if it’s likely to be a one-off job there are a couple of other options that might be worth looking at.
The first is the typical type of puller that you would find at Super Cheap and the like. This would be ok as long as you can get hold of three 80mm long ¼ inch bolts from a bolt supplies store. Here is an image of this setup in use.
The next option, which should only be used as a last resort in my opinion, is using a 3-claw puller on the outside ring of the balancer. Obviously this will only work if the rubber of the balancer is reasonably intact and definately DO NOT reuse the balancer when using this method as damage is likely (not that you would be here if your balancer is good I guess 🙂 ). Here is a pic of this setup.
Parts You Will Need
Without deliberately trying to state the obvious, at the very least you will need a new Harmonic Balancer. These retail for around the $200 mark at Repco and it can also be worth checking out Ebay if you’re not in a great hurry to do the job.
I also highly recommend replacing the crankshaft oil seal while you’re at it. These typically retail for around $18-$19 and once again can probably be found cheaper if you look around but even for that money it’s cheap insurance against an oil leak once it’s all back together.
Some high-temp silicone sealant and a few dabs of Loctite are recommended for the balancer bolt and a can of degreaser for clean-up never goes astray. The drivebelt and idler and tensioner pulleys should also be checked while you’re at it.
Doing The Job
Ok, now that we have that out of the way let’s get stuck into it. The first thing you want to do is remove the cooling fan. There are four 10mm bolts (2 each side) and an electrical connection.
Next up, remove the drivebelt. Draw a diagram of the belt layout if you aren’t sure which way it goes. There is some difference between the models but basically the tensioner needs to rotate anti-clockwise and the easiest way is to take the belt off the waterpump first.
Now we can remove the 24mm Harmonic Balancer bolt. The preferred method is with an impact gun but if you don’t have access to one a ½ inch breaker bar will do the job. What you need to do is set your socket and breaker bar up so that the end of the bar is resting on the passengers side chassis rail, like this…
Once it’s in place and you have removed everyone from the immediate vicinity turn the engine over by giving the key a quick flick. You may need to hit the key a few times before the bolt comes loose. Yes, the noise will be a bit unsettling and it’s not the recommended method by any stretch of the imagination but it does usually do the trick. Be sure to turn the ignition off before the engine starts!
Once the bolt is removed you can fit whatever puller you’ve managed to get your hands on and go about removing the old balancer. If the engine continues to rotate while you are winding in the puller bolt in try wedging a pry bar or large screwdriver between the bolts of the puller. All going well the balancer shouldn’t put up too much of a fight.
We can now replace the crank seal (if you have followed my recommendation, if not keep scrolling 🙂 ). To remove the old seal carefully prize a few sections of the large outside lip of the seal outwards until the whole seal starts moving. Doing it this way ensures that your screwdriver or whatever you are using doesn’t get anywhere near the crank.
Once it’s removed we can give the snout of the crank, including the thread in the crank for the balancer bolt, and surrounding areas a cleanup, making sure that you don’t dislodge the crankshaft key in the process.
Before fitting the seal I suggest putting a thin film of oil or grease on the running surface and at the same time cleaning the running surface of the new balancer and putting a light smear on it as well.
Now we can carefully (and squarely!) knock the seal into place, being very careful not to damage the crank angle sensor. Then fit the balancer in place, ensuring that the crankshaft key is lined up with the keyway in the balancer. I find the best way to do this is to first hold the balancer up to the crankshaft in a position that you know the keyway isn’t lined up and then slowly rotate the balancer until you feel the keyway slide over the key and the balancer push in a bit.
Next we can put some sealant between the head of the balancer bolt and the washer (to stop oil leaking) and a few drops of loctite on the thread and fit the bolt.
The bolt will take a bit of winding in, obviously pulling in the balancer as it goes, but I suggest you do this with socket and ratchet rather than impact gun just in case there are problems on the way in. Also you will be able to better feel when the balancer is all the way on.
Tightening of the balancer bolt can be done with an impact gun or a few swift hits with a hammer on the end of the breaker bar should see it go tight enough. From here it’s all down hill!
Refit the four 10mm bolts that secure the cooling fan to the radiator and DON’T FORGET the electrical connection for the fan.
Now it’s time to start her up and marvel at how quite she is again!