So last week my car began to run rough the idle increased from 900 to 1100 rpm and you could feel the vibration throughout the car. After opening the hood i notice the crank pulley had alot of movement, so i took it to work the next day my boss looked at it and told me to order the new pulley. Im a tech at m&m auto btw, i did this, while waiting for the part to come in this week i did alot of research on the problem. From what ive found the short nose cranks are the only ones that seem to suffer from this problem. I have a 1993 long nose with the 6 slot pulley, so im puzzled why mine has developed this problem. So on sunday i replaced the pulley and both acc belts, after i removed the pulley i checked the crank bolt it was torqued correctly to spec 120 lbs. So i installed the new pulley torqued 4 bolts to spec, put the 2 new belts on, start the car.... and the pulley still ******* wobbles!!!!! Is it time for the lock tight 660 fix or could it be something else? Any help would be awesome.
Thanks Greg

 

Was your keyway damaged? If so, how bad was it?

The big nose cranks are just as suseptible to worn keyways as the earlier short nose cranks. In either case, proper (re)assembly is critical to avoid damage over time.

 

Order a new Crank Pully Boss and a Timing Belt Lower Gear and install them and make sure to use locktight on the crank bolt.

I had my crank bolt come loose and it fucked up those 2 pulleys and that was why there was a wobble.

 

About 9 months after I bought my 94 miata and didn't know **** about them my crank pulley fell off on the highway, completely trashed the nose of my crankshaft. I got a crash course in miatas real fast. It can happen to any miata if that big bolt isn't replaced or torqued correctly. Recheck the keyways.

 

My 2000 had the No4 main bearing problem. Mazda replaced the engine under warranty. After a couple of thousand miles the replacement developed the same wobble you have. Mazda tried replacing the pulley without a fix then they declared the crank to be bent and replaced the replacement engine under warranty.

I sure hope you don't have a bent crank.

 

^^^ This.
Generally where there is wobble there is key way wear...which is making it wobble...which is making it wear more...etc etc

In my experience the crank nose type has little to do with it. Its the methods of working on the car. I have seen more big nose cranks and 1.8's with effed up keyways then small nose 1.6 motors.

Its possible you could have a bad pulley, but most likely you need an engine...or at least a 'liquid metal fix' to your crank nose.

 

I had to do it on my late model 92.

http://www.miata.net/garage/LongNoseRepair/index.html
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At least you'll have lots of time to fix it before that kit shows up.