Crank pulley wobble...

[gtxdave]

Wasn't to sure where to post this, so just posted it in here since it's the oldest year closest to 88.

Anyways, I went to give someone a jump today, and while I was under the hood, I noticed the crank pulley wobble...cool. It only wobbles at idle, and doesn't as RPMs increase, I remember reading somewhere before about this problem so I already knew what was up. I looked at the extra papers in my service manual binder and there was a paper for service recalls on the GTX, and one of two of the general recalls was for the timing pulley bolt may loosen...

I then got online to read up again and found that it could be more than just that, lucky for me. The engine only has 40k miles on a rebuild (rebuild included a new crank).

Could it just be a loose crank pulley bolt? Or even with the rebuild and new crank, it could be worse? Any help will be greatly appreciated, thanks.

[Tazman2]

I experienced this on my 89 n/a BF. Luckily my paranoia saved me. Jacked it up, wheel off, covers, etc. Broke the crank bolt loose with a tap on a small 3/8s wrench which basically proved my paranoia true. Since i caught it early a new bolt (torqued at the CORRECT LOWER ft lbs) saved the motor till i got rid of the car about 30k miles later for other reasons. Also another possibility is your eyes are playing tricks on you/small vibrations go through it. Mine wobbles on both my 93/95 at low idle rpms but not when reved up. And i know both are NOT small nose. So either the guy who rebuilt your motor used the older incorrect torque and/or used a old bolt. I'd take an hour or two out of your day to check. Sh*t, order a new bolt and just change it out correctly while your there!

[gtxdave]

It was rebuilt by a Mazda dealership in Ohio, so I'm gonna trust it was done right. And someone already said that my eyes could be playing tricks on me, lol, but it's definitely wobbling. Guess I need to take it apart and check her out.

So basically, I don't need to drive the car...

[gtxdave]

Also, how much should the pulley bolt be torqued at?

[gtxdave]

After looking at the rebuild papers again, it got a new pulley and bolt as well.

The parts paper from Mazda didn't have a "labor" cost on it. So it could be possible that it was rebuilt from somewhere unknown, where I thought it was Mazda.

[Turpro]

Also, how much should the pulley bolt be torqued at?

I believe I tq mine at 125 ft lbs

[gtxdave]

Before I try to do anything to the crank bolt, does it need to be at TDC?

Also, do I leave it in gear so the crank won't spin when I'm trying to take it off?

[jrally]

My GTX does this too, it's a low speed vibration that the harmonic balancer is canceling out. Once my RPMs go over about 1500, the visible wobble (very small) goes away. But, as stated, check it for piece of mind, it's time well spent to make sure things are OK.

-Jon R.

[gtxdave]

Well I took the wheel and covers off to get to the crank pulley/bolt and the bolt came loose with barely any force using a 4-way.

I dont have my impact, torque wrench or sockets, so I tightened it as hard as I could with the 4-way, and it still wobbled....yay for me so far.

I'm taking it to a shop tommorow to use their impact/ torque wrench so maybe I can tighten it down tight enough and it might not wobble. Guess we'll see. 125ft/lbs here I come

[jrally]

That sucks, sorry to hear it. Hopefully it didn't do any serious or pemanent damage. The Miata guys have a fix for chewed up keyways, but it looked iffy to me.
-Jon R.

[gtxdave]

So thinking it might be the keyway? I'm gonna put a torque wrench to it tommorow and see what happens and go from there.

[Tazman2]

Yikes! Seriously though. 125 ft lbs is NOT correct for the small nose BFs!!! Thats the problem. The original spec called for 1xx ft lbs. And the bolt stretched and loosened up. The new spec was around 88 ft lbs or so. I'll poke around and find it for you. But you NEED to buy a new bolt because yours is done!!! And crying out loud, use a f'in torque wrench after you put some blue thread locker on!

[Tazman2]

Here you go! Straight from my 1988 323 FSM manual which btw if you want cheap let me know because since i got rid of my BF i have no need for it anymore!

PS: My hosting is being ghey so i had to post it through imageshack! bah!

[gtxdave]

Yea, I was reading on miata.net and it said 80-88ft/lbs.

How much is a new bolt?

[Tazman2]

Yea, I was reading on miata.net and it said 80-88ft/lbs.

How much is a new bolt?

$10-15. But you need it lol. Just go to the dealer and make sure they order you the one for your year and you'll be set once it comes, etc. Otherwise your stretched bolt will just grenade your motor sooner or later anyways so its not worth it to save a few bucks now!