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PostPosted: October 22, 2017, 8:38 pm 
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Did a search and was surprised to find no threads on 1.8 engine rebuilds.
Looks like my planned donor is to become Mom's daily driver for a while.
Engine has to be rebuilt first.
Any odd quirks, "Gotcha's" or known weakness for a stock rebuild?
I know some OHC heads can be a PITA as if they are milled they also have to be line-bored for the cam saddles.
Some makes cranks should be re-nitrided, not cheap.
I know about the Miata 1.6 crank snout wear.

Seems a rebuild will run about the same price as a wrecking yard or Japanese import engine.
With so little difference in cost I may as well have a zero mile rebuild instead of another used engine.

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PostPosted: October 23, 2017, 2:00 am 
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Location: BC, Canada. eh?
Look closely on 1.8 motors from 1999 & 2000 model years. Crankshaft end play was a problem on some of them, due to undersized crankshaft thrust bearings, allowing the crank to move fore & aft as much as 1/2" in some cases. Those engines suffered block damage that rendered them non-repairable. The engines usually failed in the first 12-20K miles, so beware of suspiciously low mileage motors from '99 and '00.

It's easy to tell if they're okay or not. Crankshaft end play can be checked without tools & the engine still in place. Grab onto the bottom main pulley, and pull it forward & backward. If it only moves a few thousandths (still noticeable, though), it's okay. If it moves back and forth 1/8" or more, well, find a different motor.

Most of those engines were okay (mine, for example - I got lucky...so far, anyway!), but some people discovered this issue & replaced their motors before they self-destructed. There may still be some of those engines floating around out there.

Here's a link to the pertinent information on this issue:

https://www.miata.net/solo/99miatathrus ... ilure.html

This is intended solely as a "public service announcement", to save any of our valuable forum members a lot of heartbreak!

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PostPosted: October 23, 2017, 2:08 am 
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Thanks for the heads-up.
Fortunate that this one is older.
I avoid any engine new enough to have VVT.
EFI is complex enough.

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PostPosted: October 23, 2017, 2:18 am 
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Lucky! My engine falls right in the middle of the affected VIN range, but it now has about 85K miles on it & is still pretty quiet, so I guess I dodged a bullet.

You know, I should have posted this some time ago, when I first found out about it, but it slipped my mind.

Apparently, most of the engines in the affected VIN range likely got the correct thrust bearings, but (if I understand it correctly) some got undersized bearings as a result of some boxes of mislabeled bearings, shipped to the Mazda factory from their offsite bearing manufacturer.

Engine assembly techs measured each engine for end float then used one of several bearings to bring end play into spec. With wrongly-labeled (too thin) bearings, however, some engines went out with unacceptable end play, which accelerated wear on the thrust bearings. These bearings wore very quickly, and some actually fell out, allowing the crank to spin directly against the block journals.

By the way, these engines didn't have variable valve timing. That's one of the reasons I wanted a '99-'00 model - no VVT, so no premium gas required. As of the '01 model, VVT was standard, and 92 octane was mandatory. Hereabouts, where premium gas is around $5.60 per US gallon :shock: , I wanted to avoid that...

Anyway, glad to hear yours is fine!

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PostPosted: October 23, 2017, 3:37 am 
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Gee Mike,
My 20V Toyota is a 1994, has VVT, and runs fine on 86 octane unleaded. And when it hits the VVT threshold it's like a turbo kicking in.And that threshold can be set via MegaSquirt which i am using.

But if I ever have a next build I would utilize a Ztec. They sound pretty good for a donor engine.

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PostPosted: October 23, 2017, 11:13 am 
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Yeah, Larry - a lot of the VVT engines can run on regular gas - the 1.8 Miata ones, unfortunately, can't. Just a quirk of the Mazda engine, I guess. 'Course, I don't know about the later Miata engines - it wouldn't surprise me if they were tuned to being able to run regular later, as I'm sure that having to run the expensive stuff didn't help sales! I do like the way VVT engines pull, that's for sure!

I believe that the Zetec is a perfect 4-cylinder engine for a Locost, and I've yet to hear of any inherent weaknesses or issues with them, but I haven't even started my engine yet, so I can't confirm it with authority. It sure LOOKS wonderful, though!

By all accounts from the many builders in Europe, it should be excellent - bulletproof & strong, with lots of aftermarket support available. We'll see! I'm hoping for first engine start in the spring, once I've got the frame painted & put it all back together.

My original plan was to find a Miata donor, but back when I was starting this project in earnest (in the early 2000's), wrecked Miatas in my area (if you could find one at all) were in the $7K range & up. Waaay beyond my budget! Now that they're more plentiful, the Miata engines would probably be a great start.

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PostPosted: October 24, 2017, 1:28 pm 
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the only people I see rebuilding miata engines are those looking to make the bottom end hold more power. As you mentioned, used miata engines are cheap. The only thing that I would be concerned about with rebuilding the miata engine, is the timing if you have to deck the head or block.

what is wrong with your engine that suspect it needs rebuilt?

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PostPosted: October 24, 2017, 1:47 pm 
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I'm told it uses a quart of oil to the hundred miles while emitting a plume of oily smoke.
Had it running and would definitely get called in by do-gooders who would not realize I was doing my part to end Zika virus.

For the price of a used 100+K miles engine and the work of doing the exchange a rebuild just makes more sense to me.

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PostPosted: November 7, 2017, 2:46 am 
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Well, it looks like a used engine it is.
Definitely a faster way to go than a rebuild.
Got one locally for $400.00 with intact intake & exhaust, even an alternator and starter.
Unknown mileage but I did get to hear it run before pulling it.

And yah, about pulling these engines when they are to go back in. :roll:
Replacement came from a wreck, seller initially wanted to try to keep the wire harness intact but the numerous connectors are a genuine PITA.
Some are push on a little tab, some are pull, and all tend to be a little brittle.
After breaking a few and seeing how slowly it was going the side-cutters came into play.
So far I've managed to not break any on my car and I have most of them loose.

Wondering if it's feasible/easier to pull the engine while leaving the trans in place?
Remove the exhaust header and leave the exhaust intact?
I can remove the intake from the old engine first for more space, but do not want to disturb it on the replacement.

I see there are a lot of Miata forums available, anyone have a suggestion for which is best since I am not really a Miata enthusiast and only want to join one?

Not building this one as a racer, it already has several upgrades but will primarily be a "Chick Car" for my 82 year old Mom. :shock: :wink:
Once she stops driving it for whatever reason it goes back to being a donor for a Locost or other build.

The original engine gets a rebuild at my leisure.

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PostPosted: November 7, 2017, 2:16 pm 
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I found it easier to pull the engine and transmission together, but I wasn't planning on putting it back in the car. Can you even get to all the bell housing bolts with it in the car? If you do pull the tranny with the engine, drain the oil out of it first or it will spill out the back. I completely removed the exhaust before I pulled my miata engines. Intake was never an issue when I pulled my engines.

There are plenty of how to's on replacing miata engines. pick your favorite and read it front to back three or four times before you start. Take your time and label, label, label everything. I also took pictures of the labels and general location of where it was connected. Pick a system for keeping track of your hardware so you know what goes where. I have used baggies with labels inside the bag. sharpie never seems to last on the outside of the bags for me.

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PostPosted: November 7, 2017, 3:06 pm 
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Getting to the top bell housing bolts while the engine is in the car is a certifiable BUGGER!

But since you are in a junkyard if you can drop the trans to the ground and destroy the engine mounts then you can probably reach them. I was trying to work on a car that I wanted to drive as soon as I was finished so I had to be careful, you don't

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PostPosted: November 7, 2017, 5:22 pm 
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RichardSIA wrote:
I'm told it uses a quart of oil to the hundred miles

If you're lucky. On a more positive note, with reference to carguy's comments, you only need to remove one of the top bell housing bolts, as the other one is missing.


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PostPosted: November 7, 2017, 6:32 pm 
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Not in a wrecking yard and the "New" engine is already out.
Pulling it gave me some practice in keeping the numerous connectors intact.
Went looking for service parts to install before putting the engine back in.
Forget feeBay, nothing but overpriced Chinese made "Race" parts. :roll:
Moss Motors prices are no bargain either but the quality is likely to be better.
Wound up getting the new cam belt kit, clutch kit, engine mounts and exhaust manifold gasket through Amazon for half what Moss would have been.
Good saving but :BH: :ack: :twisted: that site is a pain with their overbearing "Recommendations", tracking, and pop-ups!
If I were anyone else I could probably have just left these parts alone and used the old ones as is.
But to me not doing them while the engine is out and on a stand would be foolish. :)

Taking my time with this and trying not to let it turn into another cascading "May as well do this while I'm at it" restoration project as I already have several of those.

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PostPosted: November 8, 2017, 6:20 pm 
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Completed the first pressure wash of the new engine.
Now it's clean enough to get truly clean on the second wash.

I've now discovered the least impressive engineering of the Miata engine.
You have to remove the large cast aluminum intake brace in order to get the alternator off!
Must be a real joy to do with the engine in the car. :roll:

The manual I bought arrived today.
I have to look but I'm hoping the front crank seal can be replaced without dropping the oil pan.
I will have the front group and cam cover apart anyway to replace the cam belt.

Anyone remove the tabs from exhaust that hold the ugly heat shield on?
Seems like a pointless piece to me.
I would rather see the headers than a cover with ANOTHER insulting warning stamped into it.

Glad that since I bought the new engine from a private party I do not have to give away the old engine as a core.
So I have one to experiment with. 8)
Planning to work up my own ITB and Weber intakes.
Engine would be reasonably good looking with a simpler (And lighter - smaller!) intake system.
Yes, for me appearance and simplicity count.

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PostPosted: November 13, 2017, 8:28 pm 
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Last of the "Refresh" parts will arrive tomorrow.
Then I will get to see how hard it is to replace front and rear crank seals along with the timing belt and water pump.
Definitely too much work even with the engine out to slack off and wind up having to do it later.

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