mx5autoxer

iTrader: (1)

So my crank pulley bolt backed almost all the way out and caused the water pump and alt. to stop working. Coolant temps went up and before I got home the battery died and I had to leave it in a parking lot. I took the pulley off to look at the timing belt sprocket and key/keyway. This is what the key looked like.









I decided I need a new key, but I put it back together with LocTite to get it home and haven't been driving it. I ordered one and everything was fine until a couple of days later when I got an email saying that it would be over a month until they could ship it. I checked and no one has the LNC key in stock. I can't have my DD out of action that long. Should I use a SNC key for now, tack weld the crank to the sprocket, make my own key, or drive it as is since its my only car?

And I know my keyway is pretty FUBAR but I need to make it work for now.

curly

iTrader: (25)

Wow that's all very fucked.

The real fix would be a new crankshaft, timing sprocket, key, bolt, and pulley boss. Where are you ordering that from? Rosenthal Mazda should have everything you need.

If you wanna cheap out, you could measure, measure again, and then measure again to make sure it's right at TDC and tack it. However the keyway is really the only place you could tack it, and I'm not sure I'd trust a single tack over a ~3/4" key.

bahurd

iTrader: (8)

Looks to me the key is the least of the problem. Even with a new key the keyway in the crank is pretty F'd up. A decent small shop could make you a key (assuming it really is a month...) easily and could even weld + rebroach the pulley slot if they have a Bridgeport if you can't find one at a yard.

But fixing that crank keyway...

BTMiata

iTrader: (5)

Yeah that crank is beyond repair...

Savington

iTrader: (31)

LNC keys are in stock at Mazdacomp. No reason why your dealer shouldn't be able to obtain one. B3C7-11-317

Preluding

iTrader: (10)

https://www.miataturbo.net/general-m...-pulley-77939/

Read thread above for ideas beyond JB Weld...you're going to need more then a key.

I think you should "pin".... IM humble O

Sean

iTrader: (12)

I had a similar issue on my original 1.6l. I went to tractor supply , could do home depot or lowes as well. I bought a piece of key stock bigger than the original. I got a new timing gear for the crank and with a dremel a new sharp file and a few hours of time filed a new bigger key way into the crank timing pulley and crank pulley. I then replaced the timing belt, water pump and seals. I used lock tight on the new key way and put it all together. I did this know it was a short term fix. I purchased a new used engine and put it in the garage waiting for it to break again or something to leak. I went 60K miles before I had a oil leak behind the cover at witch time I put in the new engine and junked the old one.

petrolmed

iTrader: (8)

Bro I did not realize you laid so much waste down there when you explained the key issue to me. It would be sad to see your trusty steed disassembled after all this time if the crank can't be mended. Judging by that other thread linked, I'd think you can find a solution.

psyber_0ptix

iTrader: (4)

dear lord....

It'd be cheaper/quicker to find and drop in a running replacement motor.

If you want to replace the crank, might as well refresh the whole motor

Preluding

iTrader: (10)

You'll be fine with drilling it and pinning it or even JBwelding a new piece in if you don't care that much.

Both of those are ridiculously cheap options that involve less work then swapping an engine.

TheProfessor

iTrader: (3)

There's actually a guy around here who specializes in repairing crank keyways. I haven't used him but I've heard good things from a few machine shops. I might actually get him to clean mine up. It isn't quite that F-ed up but I did have one get a little crossways with the crank at one point.

mx5autoxer

iTrader: (1)

I replaced the water pump about 20k miles ago so I'm tempted to just tack weld the crank to the sprocket. Its kinda frustrating that a really simple little thing like a keyway could junk an otherwise healthy engine.

shuiend

iTrader: (24)

It does suck a lot when this happens. It just happened to a good friend of mines NB because he did not tighten down the crank bolt enough. You want something like 125+ ft/lbs.

mx5autoxer

iTrader: (1)

I think that for future reference I am going to do and advise people to take the crank bolt out once a year, clean it, put some loctite on it, and torque to specs. How does that sound? I definitely torqued it down enough four years ago when I did the water pump and I might have used loctite, but it obviously loosened up.

shuiend

iTrader: (24)

I am blaming Manassas. I had mine come slightly loose after a few years while I lived there. I managed to catch it before it did any damage to the crank though.

mx5autoxer

iTrader: (1)

You mean Manasshole?

shuiend

iTrader: (24)

I was seeing Bad Religion at warped tour at the Jiffy Lube pavilion sometime in the mid 2000's. Greg started out the set by saying he was thankful to be in this great place call ManAssHole, instead of the vile place that is DC.

Also I just want to check that you know Rosenthal Mazda is right down 66. Tommy there will take care of you with whatever parts you need. Just if you walk in and place your order, make sure you mention wanting Finishline Performance prices and not the standard dealership prices.

Braineack

iTrader: (62)

I almost went there today. I work like 5 minutes away from it, and you work like 5min away from my house...

fwiw, like sean say, I'm pretty sure Lowes and Ace HArdware carries keys that you can make fit.

mx5autoxer

iTrader: (1)

Thanks for the input. I'm looking into pinning it, but if that isn't possible maybe the Supra Sean approach of making an new keyway, and if THAT doesn't work, **** it, I'll JB a chunk of metal in there and do it live til it dies.

mx5autoxer

iTrader: (1)

And btw, the only thing keeping me from doing it right (aka new, refreshed motor) is the fact that I don't live a half hour from my Grandpa's garage any more. We're not even allowed to change our oil in my apartment parking lot. I need to step it up to a townhouse with a garage.