Yeah, 1.8's definitely aren't immune to poor mechanic-ing! My 1994's keyway was damaged badly and the previous owner WELDED THE PULLEY ON. Super fun call to get from your mechanic!
i have a suggestion for a video: regular street driven miata fuel rail & injectors maintenance/oem-like upgrades (i know there are past injector videos, just curious for a newer look at it)
I've got a '90 with a '93 engine. That was an easy swap. If you pull the engine, replace the oil pump in the new engine going in, with a new gasket and RTV. They tend to leak where they butt up to the engine block due to a hardened original gasket. And to replace the oil pump the engine has to come out. Because the bottom part of it bolts to the oil pan and you can't get the oil pan off with the engine in the car. Unless you pull out the sub frame which is just as much work.
Sadly, as you mentioned, a bad mechanic can do the same with the big nose crank, it is just more robust. I found this out the hard way using a shop that had a good reputation to replace my timing belt. About 10k or so miles later, it got the wobble. Fortunately, by then, I had found an actual great Miata mechanic, and he was able to fix it for me as finding a replacement crank shaft was difficult. Been going strong for about 40k miles since the repair.
My mechanic had done the loctite fix on several prior Miatas with a 100% success rate at that time, so I went ahead with that, and it has been great since then.
I had the issue of the keyway on the crank nose become damaged on a 1993, despite many people telling me that was impossible. A hard accelleration would cause the crank gear to slip,, and throw off the timing, with an accompaning lack of power. If I wound up the engine to high RPMs and did a sudden engine braking, it would slip the other direction, and correct the timing isue. My shop eventually found a way to keep the gear from slipping, and I ultimately put 230k on that car before trading for an NB.
That must've been an impressively bad key way failure. It's definitely not impossible on the big nose crank engines. It just takes one person to not properly down the crank bolt and voila, you've damaged your engine.
Man you don't have to scare me like that... I did the timing belt on my '99 (BP4W) a couple years ago, and I panicked a little when I saw you demonstrate how they key shouldn't stick out past the crank nose because mine definitely did. After some quick research it looks like that's actually normal at least on the bp4w, and the outer timing guide piece that goes on the crank takes up the rest of that space so that the crank bolt doesn't shove the key in (like I thought I remembered). I haven't heard of the key having a bevel to not stick out past the crank but maybe that's different on the bp4w?
Maybe, you didn't use a factory woodruff key? Maybe there was a different spec part Mazda used for a while? Who knows? It shouldn't really be a problem unless it's long enough to protrude into the bolt and get squished. Otherwise, it's probably fine.
More of a 2 part question but pretty much a summary of the short nose crank is IF installed correctly there should be no issues? Or do issues persist regardless? I had just bought a SNC 44k miles timing belt was done by someone reputable with miatas near me. Is it worth digging in and confirming woodruff key is installed correctly, replace bolt and torque to spec?
If everything is installed correctly, Loctite is added to the crankshaft bolt, and torqued down to spec, it is of little concern what nose your crankshaft has. Most failures are related to improper torque and/or lack of Loctite.
Is it true the original woodruff key on a big nose had a bevel… like shown in your video for the small nose key… but the OEM replacements no longer do? If so, does it matter the orientation? Also, where is the Loctite supposed to be used?… on the key, the bolt or both? And is this also the factory recommendation for the big nose, or just a small nose thing? What about the 1.8?
It's possible the woodruff keys look slightly different now than they originally did, but they still have bevels on one end that should be positioned face-down into the crankshaft keyway. We recommend using Loctite on the threads of the crankshaft bolt for any B6 or BP engine, regardless of its nose.
On the Mk2 1.6s in Europe using the B6ZE engine...are you supposed to use Loctite on the Key ..I don't see that in the technician manual or anywhere else?...
The inner diameter (ID) of the crank pulleys is different between the short nose/long nose and the big nose versions. You should be able to swap pulleys between the short nose and long nose (can be identified by four long slots in the face of the pulley), but the big nose pulley has a larger ID and is not interchangeable (eight slots in the face of the pulley) with the small ID of the earlier crankshafts.
After 30 years of service the nitrile rubber in a harmonic damper doesn't owe you anything. These rubber parts continue to cross-link and to harden with time and with use. Just as rubber suspension bushings harden over time, and need replacement, so do harmonic dampers. If the engine is normally aspirated an up-rated harmonic damper will be over-specified for the job. A Mazda factory part is about $150 from a discounter. An aftermarket, stock-equivalent is around $60. Responsible builders of stock-specification 'crate' engines, & short blocks, always replace these dampers.
Im starting to have problems with my 1.6 1990 I’ve replaced my plugs n wires but I still lose acceleration sometimes while driving and my cams are pretty noisy. I’m trying to do a the cam key fix before I continue with a different decision.
I was ahead of the curve on this failure. My 89 323GT, which had the engine the Miata 1.6 was based on, suddenly lost power and had horrible fuel economy around 110K miles. I found I had a wallowed out keyway that had given me a very early and undesirable form of variable valve timing.
Yeah, 1.8's definitely aren't immune to poor mechanic-ing! My 1994's keyway was damaged badly and the previous owner WELDED THE PULLEY ON. Super fun call to get from your mechanic!
Impressive!
Oh my.
@@jaball77 what a nightmare
Agree with what he said, our shop saw just as many 1.8L crank failures as we did short nose failures. All come down to the monkey holding the wrench.
I like this young man’s stage presence
Great work at FM!!!
Thanks for watching!
i have a suggestion for a video: regular street driven miata fuel rail & injectors maintenance/oem-like upgrades (i know there are past injector videos, just curious for a newer look at it)
Thanks for the idea!
Enjoying the recent videos 👍 You guys should do one on all of the na/nb differentials and how to identify them.
Great suggestion!
Great explanation!
I always thought the instances of the short nose problem was overblown 👌
Agreed. Loud people on the internet skew opinions more than they should.
Mine got the locktite fix years ago...still holding true.
I've got a '90 with a '93 engine. That was an easy swap. If you pull the engine, replace the oil pump in the new engine going in, with a new gasket and RTV. They tend to leak where they butt up to the engine block due to a hardened original gasket. And to replace the oil pump the engine has to come out. Because the bottom part of it bolts to the oil pan and you can't get the oil pan off with the engine in the car. Unless you pull out the sub frame which is just as much work.
Sadly, as you mentioned, a bad mechanic can do the same with the big nose crank, it is just more robust. I found this out the hard way using a shop that had a good reputation to replace my timing belt. About 10k or so miles later, it got the wobble. Fortunately, by then, I had found an actual great Miata mechanic, and he was able to fix it for me as finding a replacement crank shaft was difficult. Been going strong for about 40k miles since the repair.
My mechanic had done the loctite fix on several prior Miatas with a 100% success rate at that time, so I went ahead with that, and it has been great since then.
@@beauthestdane Oof, sorry to hear that.
I had the issue of the keyway on the crank nose become damaged on a 1993, despite many people telling me that was impossible. A hard accelleration would cause the crank gear to slip,, and throw off the timing, with an accompaning lack of power. If I wound up the engine to high RPMs and did a sudden engine braking, it would slip the other direction, and correct the timing isue. My shop eventually found a way to keep the gear from slipping, and I ultimately put 230k on that car before trading for an NB.
That must've been an impressively bad key way failure. It's definitely not impossible on the big nose crank engines. It just takes one person to not properly down the crank bolt and voila, you've damaged your engine.
Man you don't have to scare me like that... I did the timing belt on my '99 (BP4W) a couple years ago, and I panicked a little when I saw you demonstrate how they key shouldn't stick out past the crank nose because mine definitely did. After some quick research it looks like that's actually normal at least on the bp4w, and the outer timing guide piece that goes on the crank takes up the rest of that space so that the crank bolt doesn't shove the key in (like I thought I remembered). I haven't heard of the key having a bevel to not stick out past the crank but maybe that's different on the bp4w?
Maybe, you didn't use a factory woodruff key? Maybe there was a different spec part Mazda used for a while? Who knows?
It shouldn't really be a problem unless it's long enough to protrude into the bolt and get squished. Otherwise, it's probably fine.
More of a 2 part question but pretty much a summary of the short nose crank is IF installed correctly there should be no issues? Or do issues persist regardless? I had just bought a SNC 44k miles timing belt was done by someone reputable with miatas near me. Is it worth digging in and confirming woodruff key is installed correctly, replace bolt and torque to spec?
If everything is installed correctly, Loctite is added to the crankshaft bolt, and torqued down to spec, it is of little concern what nose your crankshaft has. Most failures are related to improper torque and/or lack of Loctite.
Is it true the original woodruff key on a big nose had a bevel… like shown in your video for the small nose key… but the OEM replacements no longer do? If so, does it matter the orientation?
Also, where is the Loctite supposed to be used?… on the key, the bolt or both? And is this also the factory recommendation for the big nose, or just a small nose thing? What about the 1.8?
It's possible the woodruff keys look slightly different now than they originally did, but they still have bevels on one end that should be positioned face-down into the crankshaft keyway.
We recommend using Loctite on the threads of the crankshaft bolt for any B6 or BP engine, regardless of its nose.
On the Mk2 1.6s in Europe using the B6ZE engine...are you supposed to use Loctite on the Key ..I don't see that in the technician manual or anywhere else?...
We strongly recommend it.
Is the balancer interchangeable with all 3 variants: 1.8 and 1.6 short and big nose, assuming you match up the ribbing with the other pulleys?
The inner diameter (ID) of the crank pulleys is different between the short nose/long nose and the big nose versions. You should be able to swap pulleys between the short nose and long nose (can be identified by four long slots in the face of the pulley), but the big nose pulley has a larger ID and is not interchangeable (eight slots in the face of the pulley) with the small ID of the earlier crankshafts.
If you are in a position or need to change your crank pulley did you also change the woodruff key?
It's under $10 and then you know everything is as good as you can get it. Might as well.
After 30 years of service the nitrile rubber in a harmonic damper doesn't owe you anything. These rubber parts continue to cross-link and to harden with time and with use. Just as rubber suspension bushings harden over time, and need replacement, so do harmonic dampers. If the engine is normally aspirated an up-rated harmonic damper will be over-specified for the job. A Mazda factory part is about $150 from a discounter. An aftermarket, stock-equivalent is around $60. Responsible builders of stock-specification 'crate' engines, & short blocks, always replace these dampers.
Im starting to have problems with my 1.6 1990 I’ve replaced my plugs n wires but I still lose acceleration sometimes while driving and my cams are pretty noisy. I’m trying to do a the cam key fix before I continue with a different decision.
Good luck! Shoot us an email if you have any questions about it.
@@FlyinMiataVideo Thx bros
I was ahead of the curve on this failure. My 89 323GT, which had the engine the Miata 1.6 was based on, suddenly lost power and had horrible fuel economy around 110K miles. I found I had a wallowed out keyway that had given me a very early and undesirable form of variable valve timing.
Keith used to own a 323 GTX, and that community was very familiar with the failure!
Model Year is only relevant to US cars I have a JDM December 1990 with a long nose.
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