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This may be an involved question so bear with me. :)

I have a 1998 Honda Accord EX (4cyl) with 281xxx KM, and last week I was told by my mechanic that the harmonic balancer is warped. And in fact, when the engine is running you can see the crankshaft pulley wobbling rather violently way down there. I would say the wobble is approx. 5-8 mm off-center.

I am planning on having the harmonic balancer replaced very soon (as well as the T-belt, water pump, front main seal, and valve adjustment), but I am very worried that my crankshaft has been warped, or hairline-fractured, by the unbalanced balancer. The problem has been present for at least three months I think...

The car has no rust, no slipping and doesn't burn oil or coolant.

Does anyone have any speculation or experience here to give me? Is there any way to check for a warped crankshaft without taking apart the bottom end? How screwed am I?

If there's any clarification to be provided, let me know. Thanks.

UPDATE: The car is going in on Thursday and I will report back after that.

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I would think it shouldn't warp your crankshaft but I am interested to know if anyone has experience in this area. –  Rory Alsop Apr 13 '13 at 19:59
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2 Answers

Checking the run-out of the crankshaft is pretty straight forward. A dial indicator is temporarily mounted to a fixed point close to the crank. The indicator arm is set to touch the crankshaft. While turning the crankshaft by hand you will get a reading on the indicator of how many thousands of an inch the crankshaft is moving off of center. Your mechanic should be able to do this test once the harmonic balancer is removed. At that point you'll make a decision. Evaluate the rest of the vehicle. Is the transmission slipping, headgasket leak, rust issues? Is it worth putting more money in it than is needed to just get it running again. If the crank is out of spec do you just replace the balancer and run the engine until something breaks. Or rebuild the bottom end of the motor or replace the motor. If the crank is out of spec by a small amount I would replace the balancer and see if the motor runs smooth. Then do the timing belt and waterpump. If it seems ok I would drive until something else breaks.

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Can the straightness of the crank be measured while it is still in the engine though? –  i-vtec...do you Apr 14 '13 at 2:22
    
The area of the crank most likely to have damaged is the snout or the part that is exposed from the block. The reason for this is that it is unsupported by the bearings and it had an unbalanced weight spinning at 5000 rpm stuck on the end of it. This area of the crank can be measured in the car because it is exposed when the balancer is removed. –  mikes Apr 14 '13 at 10:39
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Very unlikely that your shaft is warped. They are very strong, and the balancer is there more for your pleasure and the safety of the motor, versus the safety of the shaft.

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