story:
I was worried because my T3 crank pulley was wobbling a bit at idle but went away when I revved up the RPMs... so i took off the pulley and plastic coverings and this is what i find


upload pictures online

so can someone please explain to me how this happened? I really hope all I need to do is replace this gear and NOT everything behind it (crankshaft)

Thanks in advance

-James

ok did some more research and found this: http://www.86garage.com/forums/viewtopi ... =17&t=1674

so from the look of it, this is my problem. Should I just replace this cog?

Yeah you tore up the cog. Crankshaft oughtta be ok. Might have to replace the little woidruff key. Sorry for spelling, Cinco de mayo is a day early yeah...

remove whats left, clean crankshaft snout, get new cog, new key, OEM crank pulley, the bolt you show should be torqued to about 100ft/#s... I'd recommend getting a new one.

The likely cause of this was there was insufficient force compressed against the cog and so it rocked back and fort gradually destroying it. Get a good pulley(correct thickness), a new bolt, and make sure the threads inside the snout are clean and clear.

Thanks for the quick response guys and I'll definitely get those parts on order. I'll keep you updated

one thing I'm still unsure of, the T3 pulley... what's the disadvantage to using it?

Thanks

None other than it's not dampened inside like the OEM pulley. I'll trade you my 4AGE pulley for it!

good rule to follow is always replace the keyway when u take the pulley off because the pulley is pressed onto the crank shaft to some sort meaning the keyway will have some type of compression shrinkage that wont be as tight the next time u put that pulley back on....if you keep using it that little bit of play increases until the above happens....they cost about a buck but better safe then sorry...

carbd7age wrote:None other than it's not dampened inside like the OEM pulley. I'll trade you my 4AGE pulley for it!

I'll pass thanks

Thanks for the info everyone and when I get that cog off I'll post up a better pic of the damage. Hopefully someone deciding to change the pulley doesn't make my mistake

Woodruff Key:

upload

Timing Belt Cog:

image

Besides the parts above, everything else seems ok.

For the key, is there a certain size I should be getting?
http://www.drivewire.com/vehicle/1986-t ... druff-key/
They list two sizes.

I like that they call it a camshaft key on that site, since it's for a crankshaft. I would just get an OEM key. If I can dig up the one I got for my engine build, I can take some measurements.

Yep that looks just like the one I bought on old Club4ag. Dude said it was good, off a good motor. I opened the box, lol'd, and threw it in the trash.

wow I didn't even notice that they were calling it a camshaft key lol guess I won't be going through them... I'll see If advance auto carries them or just head down to the dealership.

carbd7age wrote:Yep that looks just like the one I bought on old Club4ag. Dude said it was good, off a good motor. I opened the box, lol'd, and threw it in the trash.

should of got a refund j/k

I would have made a fuss, but I just looked in the box to make it was the right part then set it aside. However many months later when I grabbed it to put it on, I saw it was damaged. I have no idea who sold it to me!

Are these FUBAR'd keys due to no torquing the crank pulley bolt properly? Same thing happened to me when I didn't torque my del Sol's crank pulley bolt several years ago. One of the first semi-major (i.e. not an oil change) repairs I had done to one of my cars at that time, and I didn't follow the factory service manual. I paid for it several months later when that bolt came loose and ruined the crankshaft.

I also bought a 4A-FE from someone over a year ago, and it had a similar problem as pictured above. Except it was the crank pulley that had the "extra" worn out area. The key was stuck solid on the crankshaft, but so was the timing gear. The key was mashed against the gear enough to jam it in place. That engine also had two bent rods

Not enough torquws and too many revsz

I think everyone has done this at least once. I did it too. and thats what i get for not reading the FSM. but i bought a brand new woodruff and lower timing pulley from Cabe, installed and used locktite and torqued the bolt correctly.

So the key only partially engages the cog? Seems like a design flaw to me.

Cavi Mike wrote:So the key only partially engages the cog? Seems like a design flaw to me.

It holds both the timing cog and the crank pulley.

Happened to me. I have pics on the ae86irl site. Actually have a look at this YouTube vid I put up.

Type ae86 4age 20v problem in YouTube.

Another thing to note. The damaged crank gear I had was narrower to the one I got to replace it. So I reckon someone put the wrong one on at some point.

Cavi Mike wrote:So the key only partially engages the cog? Seems like a design flaw to me.

It doesn't take a lot to have the slot extended, and to install a longer key.....


But for argument's sake... the Mazda 2.3 doesn't have a key at all, it is just bolt tension that holds the Mazda 2.3 timing pulley.

Here's my crank gear,