More crank cancer

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GR8WYT

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I guess there was a reason this car was so cheap.

As some of you probably know, Gene ( GeneSHO ) and I picked up a 95 ATX for a song as a dd/beater/engine donor. The car was dirty but rust free and straight. The engine made a light "clacking" sound at idle, which we both wrote off to rod bearings, and since we had both done rod bearings, figured that was a cheap easy fix.

But... After doing some more reading, here and elsewhere and listening to some videos of other cars, I started to think this car might have crank cancer.

After taking it apart there is no doubt:

http://photoshare.shaw.ca/view/7235974501-1250369320-19808/72359/

But here's where it gets a little strange. Even though this is a high mileage car ( 175,000 miles ), there is no evidence that it has ever had a 60K. The water pump is original, it has the original crank seal ( leaky ), the original timing belt ( worn ) and there were no tool marks on the crank bolt prior to my removing it. It took 2 hard bumps of the starter to get it to release.

There may be more to this problem than incorrect torquing of the bolt on servicing. This car also has a bad tensioner in it. You can move it with your hand no problem. My thought is that all of the undamped shock of the timing belt was concentrated on the sprocket and key and finally wore them out. No amount of bolt tightening would have prevented that.

Turns out, that other cars have similar problems. I read a good article on a Mazda Miata site:

http://www.miata.net/garage/hsue/LoctiteCrank1.html

One of the other things that is stressed on other forums is the bolt itself can stretch and lose tension if it is re-used or repeatedly re-torqued. Something to consider. A quick search of some OEM Ford parts sites did not show that bolt to be available, so look after your crank bolts! Don't over-torque them, and use a thread locker to ensure that it does not loosen itself off.

I'm going to try the Loctite fix on the crank, after getting a replacement sprocket and key, and put everything back together and hope for the best.

Wish me luck...
 

boat

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So is crank cancer the widening of the timing sprocket, and harmonic balancer channels where the woodruff key goes? What in the world causes this? Incorrect torquing of the crank bolt by too much or too little?
 

GR8WYT

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I think the widening of the crank slot is truly "crank cancer". The sprocket, damper and key also suffer, but they can be replaced. Having said that, the crank slot can be repaired too, if the damage is not too great. In extreme cases, replacing the engine may be the only cost effective solution.

Certainly under torquing, or having the crank bolt loosen will cause it, but IMHO I think there are other causes too, relating to the belt tensioner, and the health of the crank bolt itself.
 
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ckinney89sho

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OK, now Im officially scared of crank cancer. I just did my front 60k and the key, the sprocket, harmonic balancer, and the key slot look really good and tight as ****. so tight I could barely get the H/B off. So I should be good rite? I mean I didnt take the timming sprocket off but it was tight when I tryed to move it.
 

GR8WYT

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s/b good. Just make sure you use an impact gun or a torque wrench ( my favourite ) to install the crank bolt when you are putting it all back together.
 

itwonder

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Good luck Kevin. I don't think anyone really knows the root cause of crank cancer, but my theory is there is more to it than a loose bolt. Yours are the best pictures I have seen of it.
 

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