The Five Most Common Mazda RX-8 13B Engine Issues. The popular Mazda Rx-7 with the 13B-REW engine was manufactured until 1995. (and until 2002 in Japan). Mazda finally released the highly anticipated RX-8 nine years later, and it remained in production until 2012. While the Rx-7 was praised for its tuning abilities, the Rx-8 was left in the dust. The Mazda RX-8 is also known for being a difficult and expensive vehicle to own. I discuss Mazda RX-8 13B Renesis engine problems and reliability in this article.
RX-8 History and Information
The 13B Renesis or 13B-MSP (multi-side-port) rotary engine powers the Mazda Rx-8. While it has the same 1.3L displacement as the 13B-REW, it is naturally aspirated rather than turbocharged like its predecessors. It produced 238hp and 159lb-ft. of torque, which was 42hp and 72lb-ft. less than the highest output 13B REW engine.
In addition to lower power numbers, the 13B engine in the RX-8 had a difficult to tune ECU. When combined with the lack of forced induction, enthusiasts were less than pleased with the performance when compared to the predecessor 13B.
Despite its lackluster performance appeal, the Rx-8 was a fun sports car to own due to its lightweight nature and superior suspension and handling. Despite its power limitations, the Rx-8 was a great platform, winning international engine of the year in 2003, best sports car in 2004, and Car and Driver’s Ten Best list from 2004 to 2006. Furthermore, it finished third out of seven cars in 2010 for Best-Handling Cars Under $100,000, proving its worth as a fun-to-drive sports car.
Mazda Rx-8 13B Engine Troubleshooting
The 13B Renesis engine is not known for its dependability. The RX-8 13B engine had a number of major issues that frequently required a complete rebuild before reaching 100,000 miles. Here are the top 5 common Rx-8 engine problems:
- Apex Seals that are leaking
- Failure of the Ignition Coil
- Flooding in the engine
- Failure of a Catalytic Converter
- Starter Error
Other Notable 13B Rx-8 Issues:
- Excessive consumption of oil
- Failure of the Clutch Master and Slave Cylinders
1. Apex Seals with 13B Leaks
Apex seals are the 13B RX-8 engine’s weakest link. The 13B rotary engine has two rotors in the shape of rounded triangles. These rotors spin within an oval-shaped rotor housing. The three ends of the triangle are the only parts of the rotors that come into contact with the housing. These are known as apex points, and each one has an apex seal that is in charge of keeping compression within the combustion chamber.
The seals are pushed outwards against the rotor housing by a spring. Because the seals and housing are both made of metal, they are lubricated with oil to prevent internal damage.
Why Do Apex Seals Fail?
A variety of factors can contribute to apex seal failure. To begin, the intake air, combustion gases, and exhaust gases all circulate within the same housing on a rotary engine. This means that the apex seals are constantly subject to temperature changes. The changing temperatures can cause the seals to wear down and crack over time.
Second, pre-ignition can generate enough back-pressure against the seals to eject the seal from the rotor and into the housing. When this occurs, the seal consumes the rotor housing.
Furthermore, because they are spring-loaded, the spring force can weaken over time, resulting in small compression leaks. Finally, low engine oil can starve the apex seals of oil, increasing friction between the rotors and housing and severely damaging both.
Metal on metal eventually wears down. When an engine revs to 9,000rpms, the seals naturally wear out faster than they would on a lower-revving engine. The 13B has two rotors, which means there are six total apex seals, increasing the likelihood of this problem occurring.
13B Apex Seal Failure Symptoms
- Compression loss
- Significant loss of power
- No starts or hard starts
- Engine stalling while running
- Misfires on a regular basis
When the seals begin to leak or fail completely, the rotor housing suffers a significant loss of compression. Because compression is such an important part of combustion, compression losses result in significant performance decreases.
Total seal failure is common on the Rx-8. Small leaks, on the other hand, are almost unavoidable on any high mileage 13B. By 100,000 miles, the seals are usually toast or leaking enough to necessitate a rebuild. If the seals pop out of the rotor and into the housing, the metal on the rotor and housing will be completely eroded, necessitating an engine replacement rather than a rebuild.
Options for Apex Seal Replacement
Apex seals are typically the cause of the 13B engine’s demise. When the seal fails, one of two things happens:
If the seals are simply leaking, you have the option of rebuilding the engine or replacing the seals. While this appears to be the simplest option, it requires pulling and completely disassembling the engine, which is an expensive and time-consuming job.
Seals pop out of the rotor: if the seals end up in the housing, the rotor will drag them against the walls, chewing the metal up and necessitating new housings. While replacing the housings and rotors can solve the problem, the cost causes most people to simply swap in a new engine or send the car to the junkyard.
There are several aftermarket options for replacing apex seals that are supposedly more reliable.
2. Failure of the RX-8 Ignition Coil
The Rx-8 is known to eat up ignition coils, which is probably the least concerning issue on the list. The Rx-8 employs a coil-near-plug ignition system, in which the ignition coils are grouped together and wired to the spark plugs. The ignition coils are in charge of converting battery power into high voltage electrical currents so that the spark plugs can spark during combustion.
On piston engines, ignition coils typically fire every other RPM. Rotary engines fire at every RPM. With a 9,000rpm redline, the ignition coils fire much more frequently than they do on piston engines. Ignition coils are electrical components that naturally deteriorate over time. They lose their ability to convert electrical currents into the voltage levels required for the spark plugs to fire as they wear down.
The Rx-8’s ignition coils usually fail after 30,000 miles. When you replace the ignition coils, you should also replace the wires and spark plugs. Fortunately, a set of OEM replacements isn’t prohibitively expensive these days, and replacing these components is a simple do-it-yourself project.
Related : The 6.4 HEMI Dodge vs. 5.7 HEMI
Symptoms of a Faulty Ignition Coil in an RX8
The following are some symptoms of RX-8 ignition coil problems:
- Misfires
- Idling in a rough manner
- Starting out is difficult.
- Inadequate acceleration
- Engine light on
3. Flooding Issues with the 13B RX-8 Engine
Driving your Rx8 through flood water is extremely dangerous. Engine flooding, on the other hand, has nothing to do with outside water getting into the engine.
The RX8 is not an environmentally friendly vehicle. Emissions are the reason it was discontinued in the UK market after 2010. When an engine is warm, it emits fewer pollutants than when it is cold. As a result, many manufacturers have different cold start cycles designed to warm up the engine as quickly as possible.
On the 13B Rx-8, the cold start cycle consists of the injectors dumping a large amount of fuel into the combustion chamber while simultaneously feeding additional oxygen into the recirculating exhaust gases to further burn the exhaust gases and heat up the catalytic converter.
If a Rx8 is turned off too soon during the cold start cycle, the engine may become flooded with gasoline. Essentially, there is a buildup of gasoline in the combustion chamber, which is too much for the spark plugs to ignite and start the engine.
Symptoms of Flooding in an RX8
- The engine will not start.
- When attempting to start the engine, there is a strong odor of gasoline.
- Engine attempting to start but failing to ignite
Basically, your engine will not start. Flooding your engine will cause your spark plugs to foul, but it will not cause any serious damage.
How to Prevent Flooding in a 13B Engine
Flooding occurs when the engine is turned off too soon during the cold start cycle. Warm up your 13B rotary engine before shutting it down. Allowing it to warm up ensures that the excess fuel poured into the combustion chamber is completely burned before the engine is turned off.
Never move your car from the garage to the driveway and immediately turn it off. Allow the car to idle for a few minutes before turning it off and revving the engine to 3,000rpms several times to burn the fuel. However, do not over-rev the engine while it is cold.
How to Drain an RX8 Engine
The fuel injectors are disabled when you start the 13B engine with the throttle wide open. So, the process for unflooding the engine is to crank it while your foot is on the accelerator pedal. Do this while the vehicle is in park or neutral.
Crank the engine for up to 20 seconds while pressing the accelerator pedal all the way down. If it doesn’t start, try cranking the engine for up to 20 seconds without pressing the accelerator. Rep this step until the engine starts. If you have to repeat the process, wait 5 minutes for the starter to cool off before punishing him or her again.
Failure of the RX-8 Catalytic Converter
On most modern vehicles, catalytic converters are the most important emissions system. The interior of a “cat,” as it is commonly referred to, is made of precious metals such as palladium and platinum. It is made up of these metals in a honeycomb structure and essentially reduces harmful emissions through chemical reactions. The harmful exhaust gases react chemically with the metals inside the catalytic converter, converting them into less harmful substances such as carbon dioxide.
The most common causes of RX8 catalytic converter failure are faulty spark plugs, spark plug wires, and ignition coils.
The catalytic converter can reach temperatures of 500°F or higher, making it extremely hot. When any of these three ignition components fails, the spark plug fails to fire, resulting in an excess of fuel in the combustion chamber. This excess fuel then enters the exhaust system and enters the catalytic converter, where it can ignite and burn up the honeycomb structure inside the cat.
When this happens, the melted metals inside the cat clog the exhaust system, causing massive back-pressure. The engine struggles to produce power and rev with this much back pressure. As a result, the most common sign of a bad cat on the Rx8 is difficulty revving the engine above a certain level. Typically, it will begin not revving above 8,000rpms and quickly deteriorate until it no longer revs above 4,000.
Symptoms of a Faulty Catalytic Converter – 13B Engine
The following are some symptoms of RX-8 catalytic converter problems:
- The engine becomes stuck revving and will not rev past certain levels.
- Significant power loss
- Engine check and limp mode
- Catalytic Converter Failure and Replacement
As previously stated, cat failure is caused by faulty plugs, wires, and coils. To avoid this problem, make sure to replace these components as soon as they begin to fail. Driving on a bad cat for an extended period of time can destroy the engine by reintroducing hot exhaust gases into the combustion chamber.
If your cat has failed, you should first replace the ignition system, followed by the cat. The first option is to replace it with an OEM cat, but these are very expensive nowadays and are not usually recommended. The second option is to purchase a catless or catted aftermarket midpipe. This is a less expensive option, and catless midpipes are less expensive than catted ones, but keep in mind that they are illegal. The final option is to gut the cat by removing all of the metal from the inside, effectively turning it into a catless midpipe, which is also illegal.
5. Mazda RX-8 Starting Issues
A starter is an electric motor that draws power from the battery to crank the engine and start it. Without moving rotors, combustion cannot occur. As a result, the starter is in charge of getting them moving so that the engine can fire up.
The RX-8’s starter is terrible at starting the car in cold weather. In colder weather, the ignition system is also poor, requiring the already weak starter to crank longer to start the engine.
Mazda simply installed a faulty starter motor in these engines. While there was an early recall in 2006, and the motors were changed as a result, older vehicles are still susceptible to this problem, albeit less frequently than 2004-2006 models. A bad starter combined with a bad ignition system results in a failed starter motor.
Symptoms of Starter Motor Failure
- Beginnings are difficult.
- There are no starts.
- The engine will not start at all.
- During cranking, there is a grinding noise.
- The starter engages but will not crank.
If you hear a clicking sound, it is most likely caused by the battery rather than the starter. If you have a faulty starter, your only option is to replace it.
6) Other RX-8 Issues
The RX8 isn’t an easy car to maintain. Its longevity is dependent on proper care. While the major issues with the 13B engine have already been addressed, I wanted to highlight a few other issues that the RX-8 encounters.
Oil Consumption of the RX8
While oil consumption in a piston engine is usually a bad sign, it is perfectly normal on the 13B. Oil naturally burns off as the engine rotates because the apex seals must be oiled.
If your apex seals are leaking, you may notice an increase in oil consumption, but it is not uncommon to need to add 1 quart of oil every 1,000-1,500 miles. As a rotary owner, you must be fully aware of this because low oil levels can cause apex seal failure. Always keep a quart or two of oil in your trunk.
Master and Slave Cylinders
The clutch on manual RX8s is problematic for whatever reason. The slave and master cylinders frequently fail. These parts failed me twice in 5 years and 50,000 miles of ownership. The clutch is extremely soft or easy to push in, which is the most obvious sign. Getting the clutch to catch becomes a nightmare, resulting in a lot of gear grinding.
Synchros in Manual Transmissions
Gear synchronizers are used in manual transmissions to adjust the speed shaft so that the collar and gear synchronize their speeds before the engine reengages the transmission. The synchros on manual Rx8s are notorious for failing, causing you to grind a lot of gears.
Overshifting or pulling/pushing the shift knob too hard or far into gear are the most common causes of synchro failure. The best $75 investment you can make is to purchase a synchro saver, which prevents you from shifting too far into gear.
Requirements for Upkeep
Maintain adequate oil levels at all times. Maintain a quart of oil in your trunk and top it off every 1,000-1,500 miles. Oil should be changed every 5,000 miles (at most). Don’t allow the engine to overheat or run out of oil.
And, my personal favorite, a redline a day keeps the mechanic at bay. Seriously, redlining these engines is beneficial because it helps to remove any carbon buildup.
Reliability of Mazda RX8 13B Renesis
Regrettably, the 13B-MSP engine is notoriously unreliable. However, the majority of RX-8 reliability issues are the result of poor maintenance. However, because of the apex seals, most of these engines will begin to lose compression by 100,000 miles.
If the engine was poorly maintained, complete engine failure is not uncommon at 80,000 miles. Even with meticulous maintenance, you’ll be lucky to get to 125,000 miles before the engine needs to be rebuilt.
Aside from the possibility of total failure, the 13B rotary RX-8 has a number of other issues. Starters, ignition coils, spark plugs and wires, clutch cylinders, and catalytic converters all fail on a regular basis. During my years of RX-8 ownership, I also encountered a number of ancillary issues such as broken door locks, waterlogged headlights, grinding synchro’s, and sway bar end link failure, among other things.
The RX8 is a fun car to own and drive, but in this day and age, I wouldn’t expect to find one that isn’t brand new. All of this explains why these cars can be had for half the price of an early 1990s Miata with double the mileage.
