The 5 Most Frequent Mazda 13B REW Engine Issues. From 1972 to 2002, the Mazda 13B 1.3L Wankel rotary engine was in production. Its most well-known variation is the 13B-REW engine seen in the iconic Mazda RX-7 from 1992 to 2002. The 13B is a high-performance engine with sequential turbocharging and a rotary architecture. Rotary engines, on the other hand, are not well recognized for their dependability or longevity. The 13B is a thrilling engine, but it is an expensive and time-consuming acquisition. This article discusses common Mazda 13B difficulties, reliability, and other topics.
Mazda Rotary Engine 13B
Mazda’s 13B Rotary engine first appeared in the Mazda RX-4 in 1972. The 13B is the most commonly used rotary engine in production cars, with a lifespan of nearly 40 years. And was first used in 1984 FB GSL-SE variants of the RX-7.
The 13B is part of Mazda’s Wankel Rotary engine range, which is named after the inventor of the rotary engine, Felix Wankel. Mazda used the 12A, a 1.2L twin-rotor engine produced from 1970 until 1985, prior to the 13B model. The 12A powered Mazda RX-series vehicles until the FC RX-7.
Throughout its existence, the 13B has had six different versions, five of which were used in RX-series vehicles. From 1992 to 2002, the Mazda RX-7 FD, or FD3S, was powered by the 13B-REW. The 13B REW and RX-7 FD are still highly sought after cars today, thanks to its twin-turbo configuration, overengineered engine, and athletic design.
Variants of the 13B Rotary Engine
Mazda 13B Rotary engine variants include:
- 13B AP (RX-3 and RX4) (RX-3 and RX4)
- 13B-RESI (FB RX-7 – GSL SE models only) (FB RX-7 – GSL SE models only)
- 13B-DEI (FC RX-7) (FC RX-7)
- Renesis of the 13B-MSP
- System 13B REW Sequential Turbocharger
For Japanese sports cars, the early 1990s were a tuner era. Japanese manufacturers were overengineering their sports cars and cramming them with turbochargers to generate enormous power in small, lightweight cars in order to compete with German performance cars like BMW’s E36 M3 and American Muscle cars like Ford’s 5.0 Mustang. The best examples are the RX7 and Toyota’s Supra.
Mazda equipped the 13B REW with a sequential turbocharger system to compete on power with a 1.3L engine. The sequential system employed two sequential turbochargers, one smaller and one larger. The smaller turbo supplied boost until 4,500rpm, at which point the larger turbo came in to power the engine until redline.
This was the world’s first mass-produced sequential turbo engine. Because of the amount of excessive heat it creates, the turbo system is a significant cause of many of the 13B REW’s regular engine troubles.
Typical Mazda RX-7 13B REW Engine Issues
Some of the most prevalent Mazda RX7 13B issues are as follows:
- Low Engine Compression and Apex Seals
- Failure of a Catalytic Converter
- The vacuum cleaner, the radiator hoses, and the wiring harness
- Extensive Maintenance Needs
- Turbo Manifold Cracks
Before we go into the Rotary 13B REW difficulties, it’s important to note that Rotary engines demand a lot of specific care. If not properly maintained, the 13B-REW engine is not a dependable engine. While the 13B has a negative reputation for dependability, this is often due to careless owners. Having saying that, the 13B REW does have a number of typical faults that appear to emerge regardless of upkeep.
1. Apex Seals 13B-REW Leaking
In comparison to a standard combustion engine with 40 or more moving components, the 13B REW has only three: the two rotors and the crankshaft. Rotors are rounded triangles that rotate in a circular manner inside an oval housing. Because of their triangular design, the rotors’ sole points of contact with other metal are their corners.
To maintain high compression, the three triangle tips must maintain an airtight seal in the housing. Each triangle corner has an apex seal that is forced against the rotor housing with a spring to make an airtight connection. Apex seals are often composed of metal, and because the housing is likewise constructed of metal, the seals require oil lubrication.
Apex seals are one of the most prevalent ‘engine killers’ on the FD RX-7. Because the seals require continual oil, the 13B consumes more oil than standard engines. As a result, extra oil is frequently required every few months.
Excessive heat from the engine, as well as a lack of oil, can cause the apex seals to wear or break. When this happens, the seals become airtight and the engine loses compression.
Apex Seal Failure Symptoms – 13B Rotating
- Idling in a rough manner
- While idle, the engine shuts down.
- Significant power loss and a lack of acceleration
Low compression can cause a variety of problems in rotary engines. The most noticeable symptom will be a significant loss of power. However, if there is only a minor pressure leak, the loss of power may not be immediately apparent.
Avoiding or Fixing Failing 13B REW Apex Seals
The best approach to avoid leaky apex seals is to keep your rotary filled with fuel at all times. Maintain an extra quart of oil in your trunk and check your oil levels often to ensure they are not too low. The FD RX-7 typically consumes 1 quart of oil every 2,000-3,000 kilometers. But, because consumption varies by engine, I always advocate topping up the 13B every 1,000 miles just to be cautious.
Sadly, the apex seals might leak for reasons other than a shortage of oil. Natural seal wear and tear is common and unavoidable. Poorly maintained 13B REW apex seals can fail between 50,000 and 80,000 miles, whereas well-kept ones can last between 120,000 and 150,000 miles.
If you have faulty apex seals, you will need to rebuild the engine or totally disassemble it to replace the seals. There is no other way to access them because they are contained within the rotor housing. If you’re going to replace your seals, I’d recommend getting a decent aftermarket/high-performance pair.
2. Catalytic Converter Issues with the Mazda 13B
Two catalytic converters are used in the 13B REW. The first cat is found within the downpipe, and the second “main” unit follows it. Due of the high engine heat generated by the sequential twin-turbo system, the first catalytic converter is prone to burning up and obstructing the main catalytic converter.
When this happens, the exhaust air flow becomes constricted, forcing air back into the engine and raising engine and exhaust gas temperatures (EGTs).
Excessive EGTs are the most visible indicator of a congested main cat. When this causes internal engine temperatures to rise, it can cause catastrophic damage to the engine’s internals and apex seals, resulting in total engine failure. Installing a catless downpipe on your FD RX-7 is the easiest way to avoid this problem. While this may cause problems with emissions testing, removing the cat can increase exhaust air flow and actually lower internal engine temps, extending the life of your 13B.
3. Failure of the vacuum, radiator hoses, and wiring harness
While the 13B REW is a small engine in general, it is also crammed into a small engine bay. Temperatures within the engine bay are also exceptionally high due to the surplus heat produced by the sequential turbo system. Excessive heat generates a number of regular failure spots in the engine bay’s different hoses and wiring. Failure of these items can result in electrical problems, boost leaks, engine overheating, and a variety of other potentially deadly issues.
Hoses for vacuuming
To function effectively, vacuum hoses must sustain internal pressure. Excessive engine heat can harden and break these hoses. When this occurs, air can leak from the hoses, lowering pressure and diminishing power and overall performance. We recommend that all vacuum hoses be replaced with wrapped silicone hoses that can endure significantly greater temperatures. The materials are inexpensive, but the job is labor intensive, needing 5-6 hours of work.
Expansion Tank / Radiator Hoses
The radiator and coolant hoses of the 13B, particularly those connecting to the turbos, are also prone to warping and splitting. There is also a radiator/coolant expansion tank that is prone to failure. We recommend that the coolant hoses be replaced with high temperature silicon hoses. There is also a simple $30 modification that will fully remove the expansion tank, preventing it from failing.
Harness for Wiring
Again, excessive heat can cause the wiring harness to become brittle and prone to failure. This will result in a variety of electrical difficulties.
4. Issues with the RX-7 FD 13B Turbo Manifold
The 13B REW turbo manifold, also known as the exhaust manifold, connects the turbochargers to the exhaust system and routes air through it. Heat cycles occur in rotary engines, as they do in all other classical engines. Heat cycles are simply the heating and cooling of engine components that occur when you warm up an engine and then switch it off to cool down.
The turbo manifold is comprised of metal, which expands when heated and contracts when chilled. The constant expanding and contracting of the manifold, combined with its connection to engine vibrations, causes cracks in the metal. These cracks might be as subtle as hairline cracks or as large as visible cracks.
Tiny hairline cracks are unlikely to create a visible performance drop, but once a crack occurs, it will worsen. When a larger fracture emerges, air begins to escape through the fissures, lowering engine pressure. Turbochargers become less efficient and have to work harder to create the same amount of power when pressure drops. This ultimately puts additional strain on the turbos, which might lead them to fail and cause power loss.
Signs of a Broken Turbo/Exhaust Manifold
The following are symptoms of Mazda 13B turbo and exhaust manifold problems:
- Limited boost, unable to generate boost
- Lack of acceleration and power
- Exhaust odors within the cabin
- The engine makes a whining or whistling sound.
- Alternatives for Manifold Replacement
If the cracks are modest, the power impact will most likely be minimal. As a result, most people will tell you that you can keep driving your engine regularly until the cracks become larger.
When the cracks get large enough to allow a significant volume of air to escape, the only replacement option is to replace the manifold itself. A new manifold will likely cost approximately $1,000, and labor to replace it will cost around $1,000 as well, unless you are capable of DIYing the repair.
5. 13B-REW Extensive Maintenance Needs
While this isn’t necessarily an engine problem in and of itself, it does cause a slew of other issues. These engines necessitate regular maintenance and attention. The majority of catastrophic engine failures are caused by owners who are not responsible or aware of the requirements of owning a car powered by a rotary engine.
While you should adhere to the suggested maintenance schedules, keep the following points in mind:
- Every 2,000 miles, add 1 quart of oil.
- Every 3,000 miles, change the oil and filter.
- Use only non-synthetic oil.
- While the engine is cold, never turn it off.
- A daily redline keeps the mechanic at bay (seriously, redlining it is good for the engine)
- Avoid overheating.
These engines are destroyed by heat. A few cooling system adjustments costing less than $100 can significantly enhance the durability of these engines. Check out the link in the following section for a comprehensive list of cooling mods.
Reliability of Mazda FD RX-7 and 13B REW
The 13B REW is a dependable engine. Yet, these engines were never intended to power 300,000-mile vehicles. They demand special care and are not the cheapest cars to maintain in the world.
Expect to repair a poorly maintained engine by 80,000 miles. 13Bs that have been rigorously maintained are likely to last beyond 120,000 miles before requiring a rebuild. Excessive heat is the number one killer of FD 13B REW engines. Upgrades to the cooling system, such as an aftermarket radiator and dual oil coolers, are recommended. This is an excellent guide on 13B REW Cooling Improvements.
Having said that, these engines have a limited lifespan. If properly maintained, it is feasible to reach the 150,000 mile mark without any severe concerns. But, the vast majority of these engines will fail before that time, and even if they do, they won’t have much left in them. Maintain the engine as though you want it to live forever, but be aware that a full rebuild will be required at some point during the 13B REW’s life.
Upgrading the cooling system, replacing the vacuum and radiator hoses, removing the downpipe catalytic converter, keeping the engine properly lubricated with oil, and according to the prescribed maintenance plan will make the 13B REW indestructible.
In terms of the engine and its internals, the 13B REW can handle up to 700whp without requiring any internal alterations. The factory turbos are reliable, however they are limited to around 350whp and 15psi of boost. If you wish to produce more power than that, you’ll need an updated set (or a single turbo).