Short nosed crank

Hi, I'm new to Mazda Roadsters so sorry if this is an old chestnut. The car that I've jus bought has the shortnosed crank. I've now read horror stories about them -how common is failiure? Morien

Reply to
Morien Morgan
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Not common, and most failures seem to be the result of replacing the timing belt without using a new crank pulley bolt, torqued to spec. I don't know if any have failed spontaneously.

Keep an eye on the front pulley. Any sign of wobble should be dealt with immediately, before major damage occurs. If it ain't wobbling and the front crank seal ain't leaking, don't remove the pulley when changing the timing belt.

I assume you've read the article in the miata.net Garage.

Reply to
Lanny Chambers

There seem to be conflicting opinions. Including the one that all of them will fail in time. From the failure of mine, I have some suggestions:

  1. If it has been working OK for a very long time, don't mess with it unless the front oil seal is really, really leaking a lot.
  2. I believe that a contributing factor is poor design clearance between the rear surface of the timing belt pulley and features of the engine block. Mine had wear marks where it was rubbing.The newer pulley is missing about
1mm of relief that was machined into the rear mating circumference of the original pulley. As a result, the new pulley is positioned forward of the engine block about 1mm more and probably will not rub. I strongly suggest you replace the pulley. I recall it costs something like $25.
  1. I am not convinced this has much to do with the bolt stretching. Since it's not a costly item, replace it anyway.
  2. Replace the Woodruff key.
  3. Read and follow the instructions on Miata net regarding the use of Loctite and use the "Loctite fix" when putting the pulley and parts back together. Even if you think everything is OK, I suggest you do it anyway.

Above all, enjoy the ride. There remains a lot to like about this car.

Ken

Reply to
KWS

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