I've got the dreaded crank pulley failure.  I've seen this occur to about 5 other 1.6L 16v engines.  Seems like some one services the Timing belt and replaces the crank bolt with no lock tite.   THe bolt vibrates loose and the lower pulley starts to rock and shake, Usually by the time you notice the issue some keyway crank and pulley dammage have occured.

So now the Real Question.  How best to repair this damage.  

1. Ideially I'd pull the engine and remove the crank having it remachined to the exact original specs and get the keyway repaired.  THen correctly install a new pulled and Key.   This would be correct but would also cost BIG $$$ and create the most down time.   Also not ideial on a 150k engine that is in the later stages of it's life.

2.  Epoxy repair,  Marine Tex or JB weld to repair the keyway and also ues a thin coat to shim the crank.   The pulley is not a Ballancer so minor deviation is allowable although you would still want it to run as true as possiable.    

What other ideias do you have?  Any tips on howto do it best or what to avoid.

                       Thanks,
                              Michael

Happened to me too.  Took my sami down for a while.  I ended up with a new motor though because of other concerns with the one I had.

I think you covered the reasonable options ... jb weld to the rescue.

I guess the another option would be junk yard pulled engine replacement ...

I think you covered the reasonable options ... jb weld to the rescue.

I guess the another option would be junk yard pulled engine replacement ...

I'm thinking JB and a new Junkyard pully, if that fails then maybe a junk yard crank ...   Hmmm we will see.  

God damn... off topic, but we really need a FAQ... I've never heard of the crank coming off and damaging stuff like that

I had that happen to me once.  When i noticed it it was too late, the timing belt pulley on the crank was so wallowed out that it walked into the crank seal on the oil pump, and started spewing oil every where.  The worst part was, i was a hundred miles from home.
Fixed it with a new timing belt pulley, keyway, crank seal, and new timing cover because the main crank pulley ate up the cover.

Hope I am not in that deep but I am loosing a good amount of oil.  The PO knew of the issue but left that info out when we made the sale.  I suspected their was an early stage problem in the crank pulley area but DROVE IT ANYWAY    ....    Well checking things over a little better last night I've decided to park the Tracker for now and place it in line for repair.

Strange but the last 1996 I bought had been repaired, I could tell because the pulley wobbled a little and TDC was before actual TDC.  Took me a bit to figure that one out.  Finally had to break out the screw driver and feel the top of the piston to correctly set the timing.    I think I finally set the timing correctly at 21 deg BTDC.

Also sorta strange But I've never seen it occur on an 8v engine.

when I had the 8v head it happend to me once , I just repaired the keyway and bought a bigger key to slide in , and that was it , but I dind't have to much damage. I didn't even thought of changing the pulley.

Had it happen to me with the 1.0 3cylinder. Previouse owner knew about it and put a large nut in the key way to take up the slack. I guess it slipped his mind to inform me about that.
Thought I was getting a deal until it jumped timing WAY out in the country.

I think I have found a workable solution and write up on this exact issue.

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


Definatly needs to go into a FAQ / repair section.

God damn... off topic, but we really need a FAQ... I've never heard of the crank coming off and damaging stuff like that

Seen the keyway damaged on 3 different 1.6l motors.  
(not just a 16v problem either)

~Nate

 this is  an  old post  but it  may be  usefull to  others like  it was  for  me  plus im  looking  for  another  fix
 the  crank I  have  in my  86 jx sammy has  the key floded over  and im  not sure  if locktite  will  fix it
 Iv  heard  of  drilling out  the  crank and gear and  installing a steel pin for  alingment  or just tig  weld it  to  the  crank
 its a HIGH mile motor and im  gathering parts  to do the 16v injected swap but  till then I  want  to keep rollin
 thanks Dwayne

Glad you bumped it.  I did my timing belt about 30,000 now.  I got those pretty tight but I think I will rechecking this coming weekend.  I posted before I did mine and I was warned about pulling the smaill bolts instead of the crank bolt but no one brought this up.

Glad you bumped it.  I posted before I did mine and I was warned about pulling the smaill bolts instead of the crank bolt but no one brought this up.

http://www.zukiworld.com/forum/index.php?topic=21088.0

http://www.zukiworld.com/forum/index.php?topic=13623.0

http://www.zukiworld.com/forum/index.php?topic=9875.0

I guess I need to replace the Calculon avatar with the Timing Problem avatar...