Kimio

I have an uncle who apparently worked on older RX7's (87-93) and he said that while the rotary is nice, the problem he often found was that at around 100k miles they required a full engine replacement as the rotary walls wore down and compression is lost due to the apex seals not sealing properly, eventually leading to complete failure of ignition, especially during cold weather.

How true is this? Seeing as I imagine 90% of the specimens available likely never saw the necessary maintenance to keep them running smoothly, I am a bit weary of some of the older cars that have a lot of mileage on them.

Do they really need to have an engine replacement even with the proper maintenance being performed on them?

lduley

iTrader: (1)

No offense, but your uncle was probably not certified mazda and just threw an engine at the car to fix it like *most* mechanics do that don't know them

The ones that were most prone to rebuild at 100K were t2's and FD's. Turbocharging an engine back than wasn't as reliable as it is now days

There are plenty of 12a's and n/a 13bs that can goto 200K with proper maintenance on stock seals

The problem is, most people are reluctant with their cars, they get in them, drive them, and thats it

Rotarys need more than that, they are like a newborn baby that needs constant attention. Oil always needs to be checked due to the oil metering system (which almost no one does until its too late). The rotary needs to run cool because it runs hotter than a piston engine. Theres also more vacuum lines (normally) than on a piston engine that are prone to cracking and creating a vacuum leak that makes the engine run the poo and people think the engine is junk

Case in point, mazda dealerships would just throw in a new engine in the rx8s cause they started to run like crap at around 40K. But, the main problem was ignition problems. Not the engine itself.

All stealerships like to get a car in and out as fast as possible with as much profit as possible, versus paying the $$$ to train their employees for the rotary, they just warrantied the engine through mazda, put a new one in, and sent it out the door, even though they didn't fix it properly

The rotary is a high maintenance engine compared to todays standards. But, the majority of rotarys are almost 30 years old. I bet when you hit 30 nothing is working quite like new anymore either . I'm 29, and the young body isn't what it was 10 years ago lol

Kimio

None taken, my Uncle is a very experienced mechanic, but I don't know how experienced he is with working on older generations of the RX7.

The model I have in mind i the early models of the Gen 3's, There are some really nice 1992-94 FD's around my base that I hope to eventually have enough money to get my hands on one. However, you can bet over 99.99% of those FD's NEVER saw the proper maintenance required to keep them running clean and smooth.

So, for someone green as grass like myself when it comes to working on cars, I want to make sure that I know what in the world I'm getting myself into and what needs to be done before I jump on getting what is likely to be a mess of a car.

lOOkatme

iTrader: (19)

be prepared to learn. the good thing about FD's is they are easy to work on but they are maintenance ******.

If you want to avoid a PITA job, ensure whatever car you do buy doesn't have a leaking oil pan, those are a pain to fix IMO.

most everything else isn't too bad. You will definitely get help from people on the forums.

Kimio

Fortunately, the Japanese are EXTREMELY big on that. If ANYTHING is leaking when it goes in for a JCI (Japanese emissions/safety inspection for the most part) the car is immediately deemed not road worthy and it must be repaired before it can be driven. So most cars here don't tend to have that problem from what I've seen so far.

Sgtblue

iTrader: (16)

Force induction creates heat. Heat creates stress. Stress shortens the life-span of engine components. In a relatively stock FD with good maintenance, adult driven and never overheated I think the usual culprit is a soft seal (coolant seal) failure around 100K.
That's the rough equivalent to a head gasket on a piston engine, the biggest difference is that it requires complete disassembly of the engine to replace. So while you're in there it makes sense to replace other wear parts...hard seals, hard seal springs etc.

Kimio

I know you need an engine winch to haul a regular piston engine out of a car, what about the rotary? I'm limited in that regard unfortunately and have to borrow equipment from a local shop.

Also, I'm looking at Atkin's Rotary Rebuild DVD, do you have any knowledge on the quality of his products?

Akagis_white_comet

iTrader: (4)

Yes you'll need some form of lifting equipment to pull the engine out of the car. Most use a hydraulic engine crane, but a simple chain hoist works equally well. IMO, I prefer the chain hoist as it gives you more precise control when lowering. So far, I've had a hand pinched twice with a hydraulic crane thanks to its rather abrupt release. The downside is that a chain hoist needs sufficiently hefty rafters to be hung from.

As for Atkins Rotary's products, they are one of the few whom I would use in my 20B. The others are Mazdatrix, Banzai Racing and Defined Autoworks

Kimio

Thank you, I plan on keeping the car relatively stock for the most part, with an exception of modifying the air intakes for the radiator and installing just about anything that can help keep the engine as cool as possible. Once I have a better understanding of the engine, then I'll look into potentially adding a turbo down the line.

But seeing as I'm green as grass when it comes to working on cars, let alone a rotary, doing anything really invasive I think may be some time down the road.

Akagis_white_comet

iTrader: (4)

While not the most attractive piece, the stock airbox/snorkel arrangement is quite good at drawing air from a very cold location (in front of the radiator). As for the radiator ducting, the often-missing undertray seems to be the common cure for insufficient cooling in a non-modified car. It forces air to go through the radiator instead of around it. IIRC, there are a few aftermarket ones available such as this from LRB Speed: FC Under Tray

Since your radiator could certainly be original and nearing its 30th birthday, it wouldn't be a bad idea to consider getting a new one such as a Koyo all-aluminum one. To get an idea of how 'intact' your radiator is, try draining the coolant from it and see what comes out. When I drained my stock one back in 2010, chunks of the plastic top/bottom endtanks were floating in the pan. Suffice to say that there was no way it could handle the extra heat of a 20B-REW in its weakened condition, so a new one was in order.

Speaking of radiator ducting, that is something I need to do as well.

Kimio

Thanks for the advice on that, I was actually planning on replacing the stock radiator for a larger one to help deal with the excess heat generation. It gets pretty warm where I'm at, so anything to help the engine stay cool, especially at slower speeds is a must. Average city driving, you rarely go above 40-50kph.

Sgtblue

iTrader: (16)

Your original post included the year range 93. FWIW, all of the models that year were turbocharged. IF that's the case with your car, you might also consider a simple boost-activated auxillary (water) injection system for additional cooling loads. Maybe a little advanced for the novice, but there's a AI section on the forum and the stickys might be worth a read at some point. The only other thing I usually recommend is buying some black 2 inch thick upholstery foam which you can then cut and stuff into any gaps around the radiator, use as much distilled water to coolant as you can safely do in your climate and change it at least every couple years.

Atkins also offers an rotary engine stand adaptor to mount the engine once removed from the car. The best $80 or $90 you'll spend vs. the alternative IMO. They use to throw in a free wax thermopellet plug (a reliability mod) with the purchase. I also have a number of vendors I use, but never been disappointed with Atkins.

Kimio

I'm still researching on what type of engine was in the later generation RX7's so that I can order the DVD from Atkins, but I remember hearing that there was some specialty tools required to work on them.

Is this true? If so, do you know if the DVD covers what these tools are?

Tim1137

Subscribed for info as well... looking at buying my first FD... and its still on its original non-rebuilt engine.

Kimio

Hey, if you're more savvy with motors than I, and need information on how to rebuild the engine, this is the DVD I was talking about.

Mazda Rotary Instructional Rebuild DVD (ARE56)

Tim1137

Oh thanks! Yea I consider myself a pretty good mechanic, I wouldn't be scared to tear one of these apart at all. That's the only reason I'm considering even buying one lol.

Sgtblue

iTrader: (16)

The 13bREW was pretty much the same in all 3rd Generation RX7s built after 1992. There were some differences in long-block components in later years...most involving sequential turbo control. But off-hand I don't recall any short block component differences so a rebuild video for a 3rd Gen should cover it.

Don't know if the DVD will cover tools. Other than a good assortment of hand tools, extensions etc, nice to have special tools that I can think off-hand would include:

*A quality breaker bar...at least 24 inches if you don't have air tools.
*Flywheel stopper...keeps the flywheel from turning when you use the big breaker bar to bust loose the flywheel nut on the back of the engine. Air tools with a strong (> 450 ft/lbs) impact is preferred and would likely eliminate the need for a stopper for this nut.
* A 54mm or 2 1/8" socket (hex if you can find it) for the flywheel nut. It will come in 1 inch drive, so you'll likely need an adaptor to half-inch drive.
* A pipe extension for the breaker bar to break loose the front hub bolt which often is even tougher than the flywheel nut. An impact of > 750 ft/lbs may eliminate this need.
* Previously mentioned rotary engine stand adaptor.
*Blind bearing puller to remove the pilot bearing. MAZDA made one which I have...or you can buy one like this Blind Hole Bearing Puller - Needle Bearing Puller
* 4 lb Dead blow hammer or a large hammer and block of wood to remove flywheel once nut is loosened.
* A box of > 5 mil disposable nitrile gloves
* A can of EASY-OFF oven cleaner to clean carbon deposits on rotors
* A utility sink or large tub to rinse said rotors after a treating and wire-brushing...and scraping seal grooves. HOT water is nice.
* A large can of WD-40 to remove water from said rotors when carbon removal is finished.
* A CLEAN and WELL-LIGHTED work space that's organized.
* A good digital camera or phone that will take flash-assisted pictures BEFORE disassembly.
* 3/8" drive torque wrench.
* A copy of the Factory Service Manual

Kimio

The idea of tearing down the engine is kind of intimidating for me, since I've never ever done something that deep before, but I'm not going to let that stop me from learning

Tim1137

I actually think these rotary engines look easier than traditional piston/rod engines to rebuild anyways. Less moving parts for sure.

lduley

iTrader: (1)

Less moving parts yes, but tolerences are ALOT tighter

Also gonna throw in there a micrometer, and feeler gauges

Sgtblue

iTrader: (16)

^Good catch.

Maybe a METRIC tap and die set to chase threads in exhaust headers and studs.

lduley

iTrader: (1)

Or everything if your like some people

Kimio

Should I be concerned about any major differences between a Japanese FD and an American one? Right now I'm looking at a RH drive model.