I am in a odd predicament and somewhat flabbergasted. Recently, I noticed the harmonic balancer on my 302 was looking rather sad and the rubber was starting to peel out of the sandwich. So, off to the speedshop; tools out and time to replace it.

Just before I started on the operation I fired up the motor for a overall flush of oil and grease around its innards, my truck is a restoration project in progress. All is well. Then I knuckled down to extracting the old harmonic balancer, taking absolute care with the puller. As you know the crank will turn as you turn the puller bolt. However, a couple of less strained turns and the crank stopped dead in its tracks. Uh-oh! Anyway, I persevered and extracted the old balancer with the least amount of effort and installed the new balancer with no effort at all.

Once I put everything in its rightful place it was time to crank the motor over. NOTHING! You can hear the starter engaging the flywheel, but NOTHING.

Now, is it possible to have moved the crankshaft; whilst removing the balancer; fractionally enough to have ceased the pistons in the chambers or, at least restrict movement? And is it really possible by ceasing the motor by turning it by hand?!

I removed the oil pan to see if there is anything out of the ordinary, no obvious gouging in the chambers; the engine is pretty wet inside, so no apparent oil pump failure and there's no "bits" in the pan.

Can anybody shed some light on this phenomena or speculate what might have gone wrong? And how could it be rectified.

 

Is the battery fully charged?

Have you tried putting a wrench on the crank bolt to rotate it?

 

is this a car motor or a truck motor. perhaps they gave you an incorrect part. for a stock motor you probably should go with a stock replacement.

 

The battery is fully charged and the starter engages the flywheel freely. I tried putting a wrench to the crank and it wouldn't move either way.

The engine is originally out of a 1970's Fairlane and now lives in my 1977 F100. As for original part or not the specifications of the part are identical to the stock part. The width, diameter, weight and counterbalance are identical. The only difference is the counterbalance weight is removable for a neutral balance.

The fact of the matter the crank is stuck solid and I can't even get to move it.

After consulting the Ford Truck manual I'll have a crack at loosening the connecting rod caps and try and pry the crank to the rear of the engine. Or check the connecting rod side clearance. This could do the trick, as I suspect the crank might have moved forward as to have pinched the pistons in the bores. If this is not the case, well, an inevitable engine overhaul and blueprinting is the next best thing to do.

 

Before you go taking the engine innards apart, remove the new balancer and make sure it isn't the issue.

The engine spun BEFORE you installed it.

If the crank can move fore & aft enough to **** pistons in their bores, it's time for a rebuild anyway.

I think something is pushed up against the timing cover by the balancer/pulley assembly.

 

No it didn't...

Not saying that the new balancer is completely unrelated and removing it won't free up the engine, but it seems really strange that while just turning the engine over by hand it stuck enough to allow you to remove the nut that holds the balancer on. Normally you need an impact wrench to remove that nut, or at the very least jam something into the flywheel to stop the motor from turning. I've never seen one that came off with normal hand tools before.

If you aren't able to turn the crank over by hand, something is wrong. How much forward/backward play is there in the crank?

 

Ooops, I see that now.

Wood block on the front of the crank and a couple whacks may tell the tale.

Pull the front cover, check for timing chain fubar, fuel pump drive fubar, other evidence on the fore/aft theory.

 

Hah! Indeed you were absolutely spot-on. Before I got all miserable on the expense of an engine rebuild I removed the balancer and was stunned when the crank moved...

On closer inspection I found a wee little mark on the back of the balancer that seemed suspect and it corresponded to a notch on the timing cover, just below the water-pump. Seems the new balancer is 10mm wider than the stock and I die-grinded the notch away so the balancer could seat properly on the nose of the crank. With the new balancer the pulley lined up almost perfect with the waterpump pulley and alternator (my truck has no power steering or air-conditioning...bare bones).

After all that panic at least I have had to replace the oil pan gaskets!!! Thus I have learnt another important lesson: never take a sales-mans word.

Thanks for the advice!