All in all, not a horribly difficult project.
If you are looking at doing this yourself, buy Keith Tanner's book. Other than the Mazda shop manual, I found it to be the most helpful.
Mazdacomp sells a gasket kit, part #8DBC-02-310, that they describe as including "all needed gaskets when replacing an engine as an assembly". They lie. That kit includes the intake and exhaust manifold gaskets, a thermostat gasket, (all needed) and a water pump gasket (unneeded in this case because the engine comes with the water pump already installed).
They do not give you the gaskets for the rear cooling housing, the water pump inlet, or the o ring for the water line between the heater core hose, the egr valve on the intake manifold and water pump inlet. All of those are required.
Buy the kit, but be aware it's far from including "all needed gaskets"
Most everything else involving pulling/reinstalling an engine has been documented on hundreds of websites, and numerous books. If you are looking to undertake this project, hit miata.net, buy the Mazda shop manual, Keith Tanners, and Rod Grainger's books, and you are good to go.
An air driven ratchet was a handy thing to have, as well as some long extensions, a torque wrench, and a universal joint for sockets. A 1-1/8" deep set socket is also required to remove the factory oil cooler. I replaced the O-ring on that cooler as well.
I borrowed a hoist from the father of a coworker, (Thanks Bill!) for the month it took me to do this job. You can buy them for less than $150, but when I was done with the job, it was nice to return it, and get it out of my way. Renting is also an option but requires relatively quick in and out to make it cost effective, and rushing this job seemed to be a recipe for disaster.
Bill also lent me an engine stand, but I never got time to find the necessary bolts to attach the engine to the stand. He's a Ford guy with all SAE bolts, and finding really long Metric bolts is harder than you think. You can obviously do this job without one, although it would have been easier on my back to have used it.
Time involved: 1 Evening for the swaybar bracket debacle.
Several evenings to disconnect everything, working slowly, and triple checking everything.
On a Saturday morning, Tim came over to help me drop the tranny and pull the engine. 1 1/2 hours. Keith Tanner's book, and the Mazda shop manual both show the preferred method is to remove the engine/tranny together. After a lot of advice seeking from a couple of area autocrossers, Tim and I agreed it was probably easier to move 2 small lumps rather than 1 huge lump.
The balance of a Saturday to clean out the engine bay, check hoses, fittings, etc. and compile a list of parts to replace.
2 evenings to swap parts from the old engine to the new. Again, working slowly and triple checking everything. I replaced the temperature sensors at the rear of the engine, the CAS O-ring, all the small water lines to and from the factory oil cooler. The temp sensors were probably overkill, but they are 10 years old, and I don't see any easy way to get to those with the engine in the car, and I wanted to get them while I could. Actually, there isn't much I didn't replace in the way of hoses, electrical connectors, and fittings. All parts bought from Mazdacomp, home of click, buy, and 2 days later UPS brings me factory parts to my door, without having to talk to an actual human being.
Somewhere in the course or putting this all back together, my Sears Craftsman torque wrench lost it's ability to measure torque. No problem, I thought, I buy Sears Craftsman for their alleged lifetime warranty on hand tools. I go to Sears, torque wrenches aren't a lifetime warranty. This is 2 times I have had a Sears hand tool break, and 2 times, it's not covered under the Sears Craftsman Lifetime Warranty that they advertise on every freakin commercial. I really hate Sears. Part of the second evening was spent procuring another torque wrench.
1 full day to reinstall the engine, hook everything back up.
Another day waiting for a couple of small parts from Mazda.
Problems I ran into that you might want to watch for when installing a motor in your Miata.
After reinstalling the engine, the wire for the EGR sensor was incorrectly routed over the EGR plumbing back into the intake manifold. The heat from the plumbing burned through the insulation on the wire, shorting it to ground, and triggering the Check Engine Light. I had assumed that in the course of cleaning out the copious amount of crud inside of the intake that I had blocked the very small opening for the EGR, and that was the problem. As I was trying to figure out an easy way to pull the intake manifold without having to pull then engine again, I saw the misrouted wire. Some electrical tape over the melted insulation, reroute the wire properly, reset the CEL, and no more Check Engine Light.
Another issue was after starting the engine for the first time, I let it idle for about 20 minutes in the garage before heading out for a road test. The radiator appeared to be full, and the temp gauge showed normal operating temps. I failed, however, to adequately make sure all the air was out of the cooling system. 1 mile into my 2 mile test run, the engine started to overheat. Water temp gauge all the way to the right, check engine light on. I pulled over, killed the engine, and popped the hood. No steam, no drama, but the oil temp gauge was showing 220, so I don't believe that I cooked the engine. Let everything cool down, limped home, let it cool down some more and pulled the radiator cap. Fluid low. Added another 2 quarts of water/antifreeze. All good now.
And that is the grand total sum of all the problems I had changing engines. Like I said, all in all, not a horribly difficult job.
Garage temp before Tim brought over his way cool (warm) propane heater. Thanks Tim!
A/C out the way, power steering pump removed.
Getting ready to pull the old engine.
Nice shiny, clean, engine right out of the crate.
Coming out.
Other Side
Nasty, greasy old engine bay. Fr. Murphy shown, but not included with this option package. :-)
Cleaned up and repainted engine bay.
Alternator, starter, oil cooler sandwich plate, and starter on new engine. This a real good time to replace all of those small cooling hoses that are impossible to get to after the engine is installed.
Fidanza flywheel 8.6 pounds on the scale.
Centerforce dual friction clutch. Leg feel is identical to stock. Much more grabbing power if I go forced induction.
Old on the hoist. New on the crate in the background.
New engine all settled in.
