Buying a 90 Miata

I am looking for a cheap Miata and found a couple of 90 Miata's nearby. I know the 90 had some issues with the keyway. What do I need to look at to make sure it won't be an issue or was not an issue that caused a problem with the car in question.

Are there any other issues I should be looking for on such an early Miata?

Check for rust in the rocker panels, common on these as we all know.

If the key way hasn't wreaked havoc up to this point it is unlikely to do so, but take a look at the pulley as a precaution, excessive wobble would be concerning.

If so these engines are plentiful. Good luck with your search, I still miss my 90.

There's a ton of good info on the Miata forum about it. Here's a section in their Garage devoted to the short nose issue. http://www.miata.net/garage/hsue/crank/loctite_1.htm

Beyond that, check for rocker rust. Check for maintenance. What plugs/wires does it have? Everyone says it likes NGK blues, so if it has something else, maybe it wasn't cared for by an enthusiast? Valve cover seals like to leak, as does the CAS seal.

I bought my '90 a few months ago. I put a new (used) rear end in it, changed the valve cover gasket, done some brake fixing. Just got it on the road last week. Having a lot of fun with it. I haven't had an early Miata in a long time, I forgot just how much they really are driving in its' purest form.

Klayfish wrote: maybe it wasn't cared for by an enthusiast?

the cheap ones I am looking at were defiantly not cared for my an enthusiast I think i will be lucky if the oil was changed on a regular basis.

I have an early NA - 1989 manufacture date. My impression is that the Dreaded Small Crank Nose Issue is a minor defect that is only an issue if the crank pulley wasn't torqued correctly on reassembly during a T belt service.

When I went through my car completely shortly after I got it, a clutch, trans, cranks and cam seals, T belt, cooling system, VC gasket were all on the list. When I removed the crank pulley the the crank nose was perfect - I used a new OEM key and bolt and followed the book on reassembly. It'll be fine for the next service interval. If it's not boogered when you get it, do a belt and get a new key and bolt and you're fine.

I'm with Motomoron. The crank nose rarely spontaneously fails. However, it's very intolerant of misassembly or incorrect torque. The later, stronger, version will also take damage if assembled wrong.

I have three Miata engines with the small crank. Or, as a friend calls it, the Light Weight Sport Crank.

The factory plug wires for the early cars were pretty bad. The NGK blues were a popular replacement, but I wouldn't get worried about something else on there.

thank you sir

Also take a look for the condition of the shift boots. Not as major as the crank, but a shifter with play equals bad shifts. Really dont know what else to add seeing the top 2 have been already covered. Missed shifts suck.

The boots don't add play, but a damaged lower one usually means a dry shift turret and thus accurate but notchy shifting. You can fix them in about 15 minutes from inside the car using two tools at a cost of about $50, so definitely not a show stopper. Poor shifting accuracy could be a few things - if you hit 5th instead of 3rd, look at motor mounts.

I replaced both boots along with the anti-rotation bushing and added an aluminum shifter bushing a while back and it has made a world of difference in the shifting.

I'll add to the chorus screaming "Don't worry that it's a 90." I had one, and it was awesome. Yeah, I had to replace the engine, but that was due to running out of oil at the track (rookie mistake, not checking it even though it had never drank oil in its life), nothing to do with the crank issue. That said, I did replace it with a 92 motor to avoid a short nose crank. 90 is also the lightest of the Miatas, so it's a great platform for upgrades.

I got one with crank keyway failure for $800 and drove it home 3 hours in the rain, with no top (and no power as the base timing is retarded when this happens.)

I followed the normal advice and the repair was successful. Sold it to a local autocrosser who put several seasons on it without the issue reoccuring.

It's 'no big deal,' and I would almost look for one so that you can get a better price.

I know Keith and others have had good luck with short nose cranks. I have not been as fortunate. I am currently shopping for 1.6 long block for my early '91 specifically because the pulley started wobbling badly at the recent "Miatas at Mazda Raceway". My trusted mechanic thinks its too far gone for the "Loctite Fix" or other shade tree repairs. In the time I have owned my Miata, the only people who have touched the crank nose area were very competent tech's at Bay area Mazda shop that Keith is very familiar with. I am looking for a large nose crank engine to replace it.

I'll reinforce Motomoron's advice. If you get short nose car. Use a new OEM key and bolt and followed the procedures religiously when it is all reassembled.

Miataman, your improved shifting was due to the replaced bushings, not the boots.

TypeQ, was there work recently done on your engine?

In reply to Keith:

Nothing has been done recently with the engine.

The slightly longer version of the story is I bought the car a little over 5 years ago. I didn't have the crank nose/ pulley assembly looked at when I bought it. It all seem to work fine until it started running wrong after a track day in 2009. At that time, I found out that the crank nose had problems. A "Locktite Fix" was done then. It worked well until Miata's at MRLS 3 weeks ago. It looks like the pulley worked its way off center during all the fun we had there.

In response to Keith:

The bushings are what made the difference in the shifter, I agree. The boots though, were way past the point of no return. Just made the mention of the boots as it is a fairly cheap and very easy replacement. Couldnt hurt to replace the boots whilst replacing the bushings.

Is it recommend to get a compression test done prior to purchase? It looks like I might be able to pick up this cheap Miata for less than $1500, is it worth taking a risk at that price?

Yes it's worth the risk! I personally wouldn't bother with a compression test on a sub-$1500 Miata but that's just me.

A compression check couldn't hurt

Type Q: Did you explicitly follow the procedure? i.e. New timing gear, woodruff key and bolt. Chase the threads, Loctite 660, correct torque, let it set up before driving, etc? Sorry it wasn't successful for you.

This issue isn't unique to Miatas, and the loctite method is successful more often than not.

On my Miata, there was probably 20 degrees of retard going on...there was a good 1/4" worn away from the keyway.

Before I threw away the engine, I'd be tempted to put a tack weld on the timing gear.

I will 2nd the its not an "OMG bad miata" problem. I've owned a few short nose cars with high miles and no issues. Ive also seen the wallowed out keyway issue on other car (the last being the first 2.2 subaru motor I put in the Wartburg) sorry but any car that uses the keyway/woodruff key method of crank pulley location is susceptible IF the person doing the maintenance isn't taking proper care while doing it. Don't blame the short crank nose, they are fine, blame the mechanic who couldn't be arsed to do the job right.

I'm with Tyler - grab the welder. What's the worst thing that could happen? You're already looking at replacing the engine. Sure, you will never be able to replace the front seal again, but that's 60k miles or more down the road.