MooreBrap04

Hello I'm 16 and I'm new to the rotary club, and my introduction isn't a good one. I recently bought a $500 2006 AT RX8, and I was told they never figured out whats wrong with it. First thing first the cat was clogged so I disconnected that. Secondly, the engine is running on one rotor(which happened three times apparently with the previous owner) and cant idle on its own. Those are the major problems as of now. The previous owner was a rotary's worst nightmare. He constantly overheated it, dogged it out, didnt keep up on the maintenance at all, and I'm assuming he was driving the car with a clogged cat for a while. Just idiotic. Ive tried troubleshooting for external problems like buying new coils, wires, and plugs but no luck. I believe its something internal involving the engine. Should I rebuild it or just leave it?

Loki

iTrader: (1)

Have you tested compression?
No point rebuilding a beaten engine, if you want one that runs, buying a ready rebuild is a better bet. Is that an auto 6-port or the older 4-port?

MooreBrap04

Ive tried the towel method and it seems like the rear rotor has lower compression than the front. Its the 6 port auto.

Loki

iTrader: (1)

Towel method?

MooreBrap04

You stick a piece of paper towel in a spark plug hole and crank the engine. The rear barely blew out the piece of paper towel.

MooreBrap04

Where can I buy a ready rebuild or a engine for a good price? Also, what's the average price for a 6 port?

Loki

iTrader: (1)

Mazda, firstly. Good rebuilders in the US include: Rotary Resurrection, Pettit Racing, Pineapple Racing. There is a list of others here on the forum somewhere.

Look for about 3-4k.

MooreBrap04

How long would these engines last with proper maintenance? Would it be a good idea to tear the one I have down and inspect it? Also, when you say beaten its just essentially junk and cant be fixed?

kops

iTrader: (1)

If it is as beaten up as you described it, the rotor housings and other internal components are likely damaged beyond repair. Of course the only way to know for sure is to tear it down... But compression test with a rotary specific tester would really be the best indicator. Mazda usually charges 1hr labor around here for one.

Paper towel method is hilarious haha I see what you are going for there but yah I wouldn't bet the house on that one!

My original engine is at 175,000km and never hesitates. With a world moving towards electric, hybrids, and 4cyl turbos... that's all fine and dandy but it makes me want to keep the rotary alive even more.

MooreBrap04

Well damn... at least I'll have something to do rather than constantly scratch my head over it lol

200.mph

iTrader: (9)

an overheated engine multiple times isnt good but on the plus side its the 6 port auto, the 4 ports are the most expensive to replace and just garbage imo. the overheating most likely damaged some key parts of the keg. Rotary Resurrection could probably get ya a rebuild at a decent price or you could buy one from mazda and not have to worry about what parts of your engine can be reused

MooreBrap04

Why are the 4 ports more expensive even though they are less desirable?

Loki

iTrader: (1)

There are fewer of them made, and original replacements from Mazda are more expensive. In North America the 4-ports were only available 2004-2005. Probably made worse because people who buy a low power auto version of a sports car are probably not as tuned into sports car maintenance as those who buy 6 ports.

spectre6000

Combination of parts availability and demand. They were only used a few years, on an unpopular trim, and people who have them either abandon them in short order or upgrade. Add that you're already dealing with a low production, high depreciation, and low popularity platform, and you've got a perfect storm.

Not sure where you got the towel method from, but I've done similar things in the past. I remember specifically sticking the finger of a glove on the end of a piece of hose, and shoving that down the intake runners on a 6.2L diesel to diagnosis a partially failing intake lifter. Nothing even approximating accurate or authoritative, but it's enough of a ballpark to tell you what's going on from 10k', or especially egregious failures. Good move. Stay resourceful and clever like that. Your diagnosis of a dead rotor is probably correct, and you're probably in for a rebuild. Can't hurt to get a more authoritative compression test, but assuming you (or someone helping you) has experience with diagnoses like that, I don't know that I'd bother with the cost of a more precise test. The numbers don't really matter after a certain point.

MooreBrap04

Yeah I might just buy a new one from Pettit or have them rebuild it maybe. Is it hard to rebuild it by myself? It's at my uncle's mechanic shop and he has 30+years of experience. So I'll have most of the tools and help(sorta). He says its easy but its complicated and may be too much for me.

spectre6000

Rotaries are some of the easiest engines to rebuild. Not everyone is great at technical things like rebuilding engines though, so that's sort of something you need to answer for yourself. You uncle's shop is one thing, but the kind of shop matters. The kind with a scanner than replaces parts probably won't do you a ton of a good unless there's someone there who's been around a while and has actually successfully rebuilt engines. Rotary specific expertise is often recommended because there are a lot of little "tribal knowledge" sorts of things (fitting seals specifically comes to mind). If he's trying to talk you out of it, it could be a clue that he doesn't think you're the technically minded sort, or that he doesn't actually want you bothering his employees, taking up space, etc.

Do some research, watch some YouTube videos, and get an idea for what's involved. It's really not hard for the right people, but everything is hard for some. Worst case scenario, even a scanner and part replacement shop should be able to swap out an engine, and rebuilt engines aren't that super expensive (at least not as far as engines go).

MooreBrap04

Ah okay I see what you mean. He says that it's a waste of money and a lot of replacing if you don't know what you're looking for(which I have a brief idea of just need to tear it down to be sure). Also he says I have to measure everything, cut the seals precisely, etc. I don't mind learning how to do it and I've watched videos about rotary rebuilds that seem precise yet simple. And yeah I think he doesn't want me taking up space in his small shop lol. I think it's a doable job just wanted to know if it's recommended since its my first time building a engine, I think it'll be fun...hopefully.

spectre6000

He's dead, Jim. You can't break it more. You have a fantastic learning opportunity though. Take it out, and tear it down. You'll probably need uncle's help (or at least the use of a tool) getting the flywheel nut off, but everything else is plain Jane tools and nominal torque values. Learn what can be learned. MAYBE it's salvageable for less the cost of a rebuilt engine. Probably not, but there's no harm in finding out. Best case scenario, you trade some time for dollars. One you have in spades at 16, and the other you don't. Worst case scenario, it's toast and more than you can handle, so you slap it back together enough to ship it in as a core anyway. Either way, you come out further ahead for having wrapped your brain around a reasonably complex machine.

Bonus: Maybe it fosters an interest in mechanical engineering or something similar. The pivotal moment in my life that set me off on the path I'm on happened when I was 16. I wanted a guitar I couldn't afford, so set out to learn how to make one from scratch, and did. Maybe this is your hand built from scratch guitar project that turns you into a successful engineer. Also, taking things apart and figuring out how they work is just fun!

MooreBrap04

Yeah i like to think of it like that. Coincidentally I was thinking of majoring in mechanical engineering after I started working/helping around at the shop. I'll learn what I can and you might be right this may be a pivotal moment in my life or something memorable.

Loki

iTrader: (1)

It sounds like your uncle has some idea of what's involved, I agree with his advice. You *can* do it yourself if you come in with the right mindset, it's not magic. The problem is that you don't have ready access to known good parts. What happens if you open it up and the housings are flaking and chattermarked? It's a waste of good seals to put an engine together like that. So now you're into spending money to replace the big parts, which is not cheap. By the time you're done you may as well have bought a rebuilt engine.

But I guess it's free to at least open the engine and have a look at what you're working with.

spectre6000

That's a great attitude! Good luck!

Exactly. Costs nothing but time to have a look-see. It's an excellent exercise to give it a critical eye. If things are cracked, scratched, flaking, gouged, etc., it'll be obvious. He'll be able to make a spreadsheet of all the suspect parts, as well as all the "good idea" parts (seals and such), dig around online to source parts, and compare costs, risks, and relative rewards between rebuilding it himself and buying a reman. If the cost of whatever housings/rotors/etc. times the uncertainty multiplier of learning mistakes and unknowns (and potentially divided by the fun/accomplishment/learning factor, since those aren't worth nothing) exceeds the cost of a reman, then go reman. If not, go forth and concur!

This is not some German turbodiesel with a crazy valve train, fragile castings, loads of secret squirrel special proprietary tools and manuals, outrageous torque specs, and so on. It's a rotary. 3 moving parts, well-documented, a bunch of normal, easily accessible fasteners you can get tools for from any FLAPS or big box (with the one exception of the flywheel nut, which is hardly exotic, just not on every corner), small, light weight, and relatively robust. Study up beforehand and as you go, and you'll do great!

TeamRX8

iTrader: (25)

grifters creed; never let an established mark walk out the door with money still in their pocket.
.

MooreBrap04

What do you mean by ship it in as core? Also what do they mean by core charge on the Pettit site?

Loki

iTrader: (1)

Core = you give them your old engine for a discount. They don't usually take dismantled engines though.

spectre6000

Correct. They "rebuild" your engine for you, but really they're rebuilding the last guy's engine. Next guy gets your engine, and so on. You'll send them a "long block", which is... would be like valve cover to valve cover on a V/H engine, or valve cover to oil pan on an inline. In the case of a rotary, it'd be the "keg" from the flywheel to the crank pulley. No intakes, plugs, coils, injectors, or any other thing that's bolted onto the block. Just what's inside the block. If you tear your engine down and decide to have it rebuilt for you once you're in there, you'll need to be able to get it back together so you have something to send them back. That's what I/they mean. Alternatively, you can eat the core charge and increase your spreadsheet line item expense for the rebuild accordingly.

Watchmakers deal with much more complicated, fragile, and complicated machines. Often more expensive as well. A lot of them (at least the modern ones) will take a billion photographs, or even video as they work disassembling the movement (the "engine" of a watch), and use that as reference for putting it back together once it's cleaned and whatever parts have been sourced. Might be a good strategy for you. Manuals are one thing, the exact machine and parts you're working with is another entirely; no need to try to interpret different versions of line art drawings of complex three dimensional parts.