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Rotary Maintenance and Troubleshooting Tips

Postby Razkal » October 23rd, 2007, 10:06 am

In light of all the 2nrs wanting to blaspheme against the RX7s by swapping piston motors in (mine came that way eh fellas...dont hate just yet :lol: ), i've decided to try posting some tips n lil articles i got here and there to educate the guys who are not too enlightened abt the rotaries so they'll undersatnd a bit more n not think they're noise-making, spontaneously combusting, unreliable pieces of crap...

here goes..

SOME ROTARY FACTS:
• The rotary engine is actually very reliable, no matter what anyone says. Odds are that a person saying the engine is not reliable doesn't know what they are talking about, modded his/her car improperly or didn't take care of their engine.
• All 3rd Generation RX-7s (1993-present) are twin sequential turbo, twin rotor 13B-REW engines. There were no naturally asiprated, single turbo or three rotor 3rd gen. RX-7s produced from the factory.
• The different generations of RX-7 are usually referred to by a two letter code taken from the VIN number. First generations ('79-'85) are FBs, second generations ('86-'91/92) are FCs and third generations ('93-present) are FDs.
• The FD is still being produced, but only in Japan.
• FCs have passive rear steering, which Mazda refers to as the "Dynamically Tracking Suspension System", or DTSS. If you don't want this (for drag racing, etc.) then you can buy special bushings to remove it.
• FCs came in both intercooled turbo and naturally aspirated. In the US, all convertibles were naturally aspirated, but in Japan and other areas of the world they were turbo. The naturallty aspirated FC was not available in Japan.
• The turbo FC is called the "Turbo II". This is not because it has two turbos, but because the FB was available in Japan as turbo.
• The 13B rotary engine in the 1989-1991 RX-7 has the highest power to displacement ratio of any naturally aspirated engine produced.
• Rotary engines respond to common modifications like intake and exhaust much better then piston engines. However, if you have a turbo rotary and perform the preceding modifications, it is now time to upgrade the fuel system. If you don't, you will most likely run lean, detonate and then blow the engine.
• The rotary's strong exhaust pulses are also much better for driving a turbocharger than a piston engine.
• The rotary engine burns oil by design, unlike piston engines that burn oil as they wear out.

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Postby Razkal » October 23rd, 2007, 10:19 am

GENERAL INFORMATION ON SOME ROTARY ENGINE TYPES:


10A Rotary Engine
The Cosmo 110S Sport, Mazda's second rotary engine car, the R100, and the RX-3 were powered by the 10A engine. It had a capacity of 491cc x 2 and was available in naturally aspirated form only using a carburetor.
12A Rotary Engine
The 12A engine had displacement of 573cc x 2. It was first introduced in May 1970 in the RX-2. The size of the rotors were the same as the 10A, yet their width increased by 10mm as did the rotor housing to increase the engines capacity. It was also available in the RX-3, RX-4 and RX-7 as well as the Japanese model Cosmo. In Australia it was only available in naturally aspirated, carburetor form. There is a fuel injected, turbo charged version available though which was in the Japanese RX-7 and Cosmo.
13B Rotary Engine
The original 13B rotary engine was introduced in December 1973, mounted in the RX-4 (or Luce in Japan). The 13B engine displaces 654cc x 2, the width of the rotors and rotor housings are increased by a further 10mm over the 12A. The 13B was available in the RX-4, RX-5, second & third generation RX-7s, the JC Cosmo and the later model Luce (929). The last two models were only available in Japan. Originally only available in naturally aspirated and carburetor form, later versions were fuel injected and featured one turbocharger, twin sequential turbochargers or a six port induction system, similar to Honda's VTEC system. It is the most common and popular rotary engine to modify, with many EFI 13B Turbo's finding new homes inside older model RX's.
20B Rotary Engine
The 20B is currently Mazda's largest production rotary engine. With a displacement of 3 x 654cc, an extra rotor is added to the 13B engine to create the 20B, the rotor width remains the same as the 13B. The 20B is a much torquier unit, due to the extra rotor, and also does not need to be revved as hard to make as much power. This helps to make the 20B a very efficient and powerful engine. Only available in the JC Cosmo, it is a rare engine.


10A
982cc (1 litre)
2 x 60mm wide rotors
Carbureted
Image

12A
1146cc (1.2 litres)
2 x 70mm wide rotors
Carbureted/EFI
Image

13B
1308cc (1.3 litres)
2 x 80mm wide rotors
Carbureted/EFI
Image

20B
1962cc (2.0 litres)
3 x 80mm wide rotors
EFI
Image


http://www.mazdarotary.net
http://www.mazdaclub.net
http://www.tripod.com\craigsrotarypage
http://www.therotaryshop.com
http://www.nopistons.com
http://www.fullboost.au
http://www.mazda.gr
http://www.rotaryeng.net
http://www.freeengineinfo.com
http://www.pettitracing.com
http://www.rx7.com

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Postby Razkal » October 23rd, 2007, 10:26 am

IS MY ENGINE BLOWN?
The rotary engine is very reliable. With only 3 major moving parts, it is immune to the little problems that may plague piston engines. However, because the rotary relies on such few major parts, this also means that it is more likely that a failure of an internal engine part will be catastrophic. Combine this with the general lack of knowledge on the rotary possessed by the general public (with regards to operation, maintenance and modification) and you will find that the "blown engine" is more likely to happen in a rotary then a piston engine. This is simply the reality of the RX-7, and should not be taken to mean that the rotary is unreliable and prone to destruction. It just means that proper maintenance and operating procedures should be observed.
Many potential buyers look at cars with a supposedly blown engine as a way to save money, or start the buildup of a high horsepower car by installing their own fresh power plant. Others are experiencing weird symptoms that can indicate a blown engine, but are not sure. For example, stuck fuel injectors can produce the exact same symptoms as an engine that has lost compression, as can malfunctioning ignition systems. This document is to assist this person in determining whether or not the engine is blown.
But first, let's decide on what exactly "blown" means. For this document, blown means that the engine has lost compression on one or more rotors. This is normally due to apex seal failure. The seal cracks, pits or just plain gets ejected from the rotor, causing two rotor faces to lose their compression (one apex seal is responsible for sealing two rotor faces). Often, the damaged seal will travel around the housing as the engine rotates, crashing into other apex seals and damaging them as well. The result is a bad housing, and probably a damaged rotor. Small cracks can also form in the apex seal, resulting in much lower compression then normal, but no other damage to the housing or rotor. The point is that it is fairly easy to find a blown engine with a simple compression test.
The Mazda compression tester is the quickest and easiest way to determine the compression of a rotary engine. However, since these units are quite expensive, we can assume you don't have one. If you do, then obviously you wouldn't be reading this document so there's no real point in telling you how to use it. A simple tester can be made by using a standard automotive compression gauge. Remove the one way check valve, and install the tester into the leading (lower) spark plug hole in the front rotor. Make sure your battery is fully charged, remove the EGI fuse, then floor the pedal and crank the engine while an observer looks at the gauge. You are not looking for excellent numbers, just three even bounces above 70 PSI. If the rotor has lost one apex seal, you will get one strong bounce followed by two very low bounces. If all seals are damaged, then you will get three bounces that barely register on the gauge. Repeat for the other rotor.
If you don't have a compression tester, it is actually still very easy to determine the state of an engine. Remove the leading spark plug from the front rotor, make sure the battery is fully charged, and then crank the engine while listening to the air exiting the spark plug holes. It should be an even rhythm of "psssst" sounds, one per every half revolution of the eccentric shaft. Something like "psst...psst...psst...psst...psst...psst". An engine with a bad seal will be very obvious in that you will hear an irregular pattern of "psst" sounds or one "psst" for each revolution. For example, you would crank the engine and hear ".........psst...psst..................psst...psst...." or something like "psst.............psst...........psst.............psst.". To help you recognize the sound, a recording of a blown engine is below. This engine lost a seal in the front rotor, leaving only one rotor face with compression. It is in Microsoft Wave (.WAV) format and is playable on probably every machine out there.

Blown Engine Recording
Notice the long pauses between "psst" sounds. A good engine will have a steady beat of "psst" sounds that are strong, and well pronounced. On the off chance that you have a bad side seal, you could hear a pattern of two "psst" sounds, a pause, then two more. This will look like "psst...psst..........psst...psst.......". The engine is still blown, but all the apex seals are intact. An apex seal failure will always result in the loss of compression on two rotor faces, and thus one "psst" with a long pause before another.
What if the engine is out of the car? Well, you can't do a proper compression test, but you can at least check the general condition of the seals, and normally tell if it has low compression.
You will need to arrange the engine so that you can get access to the 19MM bolt at the front pulley. Remove the exhaust manifold, but leave the spark plugs in place. Now, using a 19MM wrench, turn the engine over three times. While you are turning it over, listen for a distinct "chug" every half turn. This is caused by the pressure differential as the rotor sweeps by the exhaust port. If a chug is missing, or sounds significantly weaker then the others, then you have a problem. As with the "psst" test, a chug will normally be missing for two rotor faces.


http://www.aaroncake.net/rx-7/blown.wav
www.aaroncake.net has some pretty cool and accurate info. thats a recording of a blown rotary engine btw...it sounds JUST like that.

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Postby Razkal » October 23rd, 2007, 10:33 am

OVERHEATING YOUR CAR:
Most RX-7 owners will never have to worry about an overheated car, but if you are one of the unlucky ones, the information on this page should be useful. By now, I'm sure you know that rotary engines don't take to overheating very well. Overheating usually results in warped housings, which results in the water o-rings not seating very well. This condition causes coolant to leak into the combustion chamber. Obviously, this is a bad thing.
If the car is overheating, the first thing to do is pull over. If you were running the car hard and idling would help reduce the temperature of the engine in a natural way, let it idle until the temperature gauge reads normal temp. If the car suddenly overheated due to lack of coolant or other reasons, shut off the engine immediately and allow the car to completely cool down.
With the car cooled down, it may be driven to a convenient place and examined for damage. If the car begins to run hot again, shut it down and have it towed.
Does the car still run? That is always a good sign. What you want to do is look for possible damage. Does the car belch out huge clouds of white smoke after it is started? This could be caused by coolant leaking into the chamber and being burned off by the running engine. It is rather normal for an engine to expel a could of steam when cold started or operated in cold weather, but excessive amounts of sweet smelling smoke almost certainly indicate burning coolant.
Does the car consume coolant, with no noticeable external leaks? If you continue to add coolant to the car with no external leaks seen on the engine, it may be being burned. The coolant may be leaking into the engine internally. This is what creates the cloud of white smoke. The best way to test for this condition is to look for bubbles in the coolant. With the car completely cold, remove the coolant filler cap. Now start the engine and look at the coolant through the filling hole. Do you see a steady stream of bubbles coming from somewhere in the engine? Now, rev the engine by grabbing the throttle lever at the front of the engine. Does the coolant bubble up and/or gush out? If these two conditions are present, it is a pretty good sign that the coolant O-rings are leaking and allowing coolant to enter the engine, and combustion gas to enter the coolant.
If you have performed the above test and suspect engine damage, it is best to have the cooling system pressure tested to be absolutely sure. Any damaged pressurized system will leak coolant into the engine, resulting in hard starting and cloud of white smoke. Most rad shops can provide this service.
Now, if the car shows no loss of coolant and still runs properly after being overheated, consider yourself lucky. Now would be a good time to figure out what caused the initial overheating and correct it so the situation does not re occur.
If you have suffered engine damage, the only cure is a full rebuild. The car may still be driveable, but the condition will continue to get worse until the car no longer runs. This may take days, weeks, months or even years. There are various temporary fixes that can be employed, but they are just delaying the inevitable. Better start saving for that new engine.

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Postby Razkal » October 23rd, 2007, 10:42 am

To help cure overheating issues on track cars etc, most RX7 guys, opt for a V-Mounted style radiator and Intercooler, this bypasses the 'ever-so-cool' looking FMIC setup, but allows MAXIMUM airflow over the radiator AND intercooler, which mean su can run the car harder, for longer without worrying, big FMICs usually block the entire effective cooling surface of radiators and therefore leave them relying on the fans alone...
Also, because the RX7s usually have a lot of room up front owners can affor to mount the intercooler topside infront the motor and the radiator at an angle to its vertical stock position..

Image
^S13 with V-mount set up

Image
^FD RX-7 with V-mount set-up

Image
^Fd with V-mount set-up...u cud see the radiator in the front air-dam mounted at an angle..this car is sweeeeeet :oops:

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Postby Safeq » October 23rd, 2007, 11:51 am

Thanks Razkal hopefully people now getting into the game can make a wise informed decision from the info provided rather than going on hearsay from non rotary owners

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Postby Razkal » October 23rd, 2007, 12:04 pm

will post more as time permits...no probs man.

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Postby demented » October 23rd, 2007, 12:42 pm

Nice post :wink:

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Postby Razkal » October 23rd, 2007, 12:59 pm

feel free to add or correct as u guys see fit...pics would be nice as well...n post lots of links..make this the rotary education thread :wink:

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Postby Zorak » October 26th, 2007, 8:03 am

i love me some free education! :mrgreen:
so by d time i buy mih rotary next year i should have mih B.Sc in Rotary Management!
thanks man!

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Postby Razkal » October 26th, 2007, 8:24 pm

The "ATF Trick": The Real Truth
If you have been involved in the RX-7 community, you have probably heard mention of the "ATF trick", or "ATF treatment". It is often prescribed for serious flooding situations, and sometimes as a general maintenance item. Especially on a certain forum. However, misunderstandings about the use of automatic transmission fluid, or ATF, in rotary engines has caused damage to quite a number of cars. I am hoping that this page will provide a little info on the "ATF trick" that is rarely heard.
Basically, the ATF trick consists of introducing automatic transmission fluid into the working (combustion) chamber of a rotary engine. This is usually done by removing the leading spark plugs, and using a funnel and tube to pour a few ounces of fluid into the engine. The engine is then either rotated by hand or cranked over with the starter to distribute the fluid inside the engine. Common practice is to then leave the car overnight to allow the fluid to "do it's magic". The idea is that ATF dissolves any carbon deposits and cleans out the internal mechanism of the engine. ATF is also used in a situation of severe flooding. It is again poured into the engine through the spark plug holes. The ATF absorbs the extra fuel, and allows the apex seals form a better better seal and build up compression. The engine then starts and burns off the ATF.
The problem is, quite a number of people use the ATF trick as a general cure-all. What they don't realize is that ATF is in fact bad for the engine. ATF is a fairly corrosive liquid, designed for the environment in an automatic transmission. The seals and materials in an automatic transmission are different than those in the working chamber of your engine. While ATF may not be corrosive to the bands, clutches and gaskets in an automatic transmission, it is corrosive to carbon (which is good, and why it cleans the engine) and has been shown to affect the rubber O-rings used to seal the rotor housings together, as well as the o-rings used on the oil seals. ATF attacks all those seals, and if they were marginal to begin with, they will most certainly be ruined by the ATF trick. This is why there are so many complaints that sound like "I did the ATF trick a week ago and now my car smokes and burns oil". The ATF has damaged the seals, allowing oil to leak into the working chamber and be burned off. This is bad, and can only be cured by replacement of the seals, which of course requires disassembly of the engine. Since the ATF trick is most often used on marginal engines to try to increase the performance, problems are fairly common. So using ATF as a general "cure all" or engine cleanout method is not a good thing.
Another use is to try and free an engine that has become "carbon locked". Carbon locking occurs when a chunk of carbon dislodges from the rotor housing and jams the apex of the rotor against the housing. This prevents the engine from turning. ATF is poured into the engine in an attempt to dissolve the carbon. This procedure is entirely acceptable, as a carbon locked engine is usually on it's last legs anyway, and there's not a lot that can be done to make it run any worse. Because of the damage caused by carbon locking, the engine usually blows shortly after the carbon has been cleared.
Excessive use of ATF also has other side effects. For one, the spark plugs are fouled much more quickly. This is due to the deposits that build up as the ATF burns. It may not be a big deal, but fouled spark plugs need to be replaced otherwise they will cause loss of power and gas mileage. The same deposits that clog spark plugs are also blown into your exhaust. If you are running catalytic converters, the soot and forign matter may begin to clog up the honeycomb inside. If the converters were already marginal to begin with, the ATF treatment may be the "last straw". Of course, the engine oil should always be changed after using ATF since it will be contaminated. A slightly more amusing side effect are the intense clouds of strange-smelling white smoke. Be aware that the ATF trick will produce enough smoke to fill a neighbourhood quite effectively. This has resulted in concerned neighbours calling the fire department, police, etc.
The original use for ATF was to clear flooding. It is entirely acceptable in a situation of severe flooding to use ATF to restore engine compression and allow the engine to be started. ATF does not usually sit in a flooded engine long enough to cause damage to the seals, as shortly after the ATF is poured into the engine it is burned off on startup. However, oil works just as well and is much more benign.
There you have it, when you can and when you cannot use ATF. I hope that this saves at least a few cars out there.

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Postby Razkal » November 19th, 2007, 8:43 pm

bump for noobs...

come on Maelstrom, GT Racing, furness....all u rotary guys, share some knowledge
Safeq, u too!! :lol:

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Postby Maserati » November 19th, 2007, 9:05 pm

good thread

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Postby Razkal » February 6th, 2008, 10:33 am

^BUMP^
take a read n00bs 8)

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Postby Placide » February 6th, 2008, 2:26 pm

Thanks Razkal! Good info here. Keep it coming, knowledge is power and I want to learn as much as I can before I dive into my project :wink: :wink:

Safeq, the guy sold the RX2 already :cry: Still on the hunt, so any leads on a good 1st or RX2 will be greatly appreciated guys.

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Postby Safeq » February 6th, 2008, 8:18 pm

Oh hoh Placide

Will keep an eye and ear out for you

Actually I know a guy with a sweet 1st gen

I'll ask him if he's selling

I'll try to get a pic nonetheless

Will get back to you

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Postby Placide » February 6th, 2008, 9:12 pm

Thanks Safeq!!!

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Postby Glitch » February 7th, 2008, 10:12 am

Nice tread bro...I going and check my compression this weekend - "psst...psst...psst...psst...psst...psst". :mrgreen: fingers crossed

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Postby Razkal » February 7th, 2008, 10:51 am

^good luck man! 8)

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Postby Razkal » April 13th, 2008, 5:23 pm

Raaaaaaaaatatatatatataaaaaaa *phew* RAAAAAAAAAAAAAAAAAAAAAAAAAAAATATATAAAAAA *tail lights in distance*

^BUMP^ :mrgreen:

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Postby red bwoy » April 13th, 2008, 7:19 pm

well done razkal if you don't already have it i have some factory service manual and a training software for the rotary engine and mazda transmissions allyuh hav to do is ask i'll post it or pm yuh de link

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Postby Razkal » April 15th, 2008, 10:53 am

^dont wait for me to ask bro :lol:
post anything you have that will shed light on rotaries; maintenance articles, modifying tips/tricks/procedures/links/suppliers, repair/rebuild/diagnotic articles..
anything you haev man.
I haev PDF versions of all the service manuals for RX7s, but they're HUGE so i can probably dig back up the link i got 'em on and post for those who wanna download and read..

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Postby mafia generation » April 15th, 2008, 11:34 am

this is a dread post dawg!!!

don't on a rotary but still a bes post... :lol:

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Postby 'Teen » May 2nd, 2008, 9:33 pm

Wonderful thread, and very important info.
Up to a couple years ago I asked my mech, about testing compression and he informed me that only 4 or 5 people in trini could have done it.
It's good to know that there's a way owners can do this themselves without having to fork out cash!!
The engines are finiky, but lemme tell u guys, after your first taste of ROTARY POWER....u like a junky...CAN'T WAIT TO GET YOUR NEXT FIX!!

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