In 1996, Porsche unleashed what would become one of its most divisive and troubled flat-six engines ever produced. Soon after the launch of the M96 boxer six-cylinder, folks began to experience serious issues with the mill. Some of the problems rendered the engine completely unusable. Because of the flaws, the M96 engine turned the prospect of Porsche ownership from exciting to a major financial gamble for many new owners, in addition to second-hand buyers today.
However, Porsche didn’t waver for long in fixing the mistake, and the Stuttgart-based automaker decided to revamp the flat-six completely. The result of the efforts was the 9A1, also called the MA1. It launched with the 2009-2012 Porsche Boxster (known internally as the 987.2 for the refreshed version of this model) and the 2009-2012 911, which the automaker calls the 997.2.
The M96 Had High Hopes, But Packed An Unintended Weakness
1996-2002 Porsche BoxsterPorsche
In 1997, Porsche was poised to introduce one of the most significant changes to its historic model lineup ever seen. That year, the 2.5-liter M96 flat-six engine launched. It was the first mass-produced water-cooled engine ever developed by the company. Almost immediately, the mill divided Porsche fans in a major way. On the one hand, you had folks who were happy Porsche was moving with the times. On the other hand, purists argued that Porsche had lost its way by axing the old-school air-cooled engine. Alongside the original 2.5-liter iteration, Porsche also produced 2.7-, 3.2-, 3.4-, and 3.6-liter versions.
Not only was it water-cooled, but the engine also packed a few key upgrades that set the unit apart from previous Porsche road-going powerplants. For starters, there was an integrated crankcase that blended the case directly into the engine block rather than being separate pieces, which improved structural rigidity. The mill also had a modular construction, meaning production costs were much lower than previous engines. It was smaller and more efficient, meaning packaging was easier, and emissions were cleaner.
1996-2002 Porsche Boxster rear 3/4 angle in green while parkedPorsche
However, alongside the upgrades were a couple of key downsides, one of which was cylinder bore scoring, which was especially an issue on the larger-displacement versions. The mill’s cylinder walls were coated with a special aluminum-silicon material called Lokasil. Over time, this material would break down, causing the piston rings to lose a tight seal. The M96 also suffered from uneven thermal cooling, and its open-deck design caused torsional stress, meaning the engine itself could flex under heavy load, throwing off its piston geometry.
The largest Achilles’ heel suffered by the M96, though, was Intermediate Shaft (IMS) bearing failures. The intermediate shaft sat behind the engine’s flywheel, and Porsche employed sealed bearings that relied on their own grease supply, rather than using engine oil. This grease would break down, along with the seals, potentially causing catastrophic failure. Hot engine oil washed away the factory lubricant. Once the IMS bearings failed, the engine could jump timing, and metal debris scattered throughout the engine could cause complete engine failure, namely piston seizure.
The M96 engine failures irreparably damaged the mill’s reputation. However, the brand moved quickly to rectify the situation, beginning with small tweaks.
In Stepped The M97, But It Didn’t Solve Everything
Front shot of a 2005 Porsche 911 CarreraPorsche
Beginning in 2005, Porsche’s improved M96, called the M97, arrived. This time around, the engine was available as a 3.4-, 3.6-, or 3.8-liter variant and was initially offered in the Porsche 911. Later, the Cayman and Boxster received the powerplant, too. Among the various changes made, Porsche introduced the M97 with revised cylinder heads with improved flow and better thermal displacement. It also introduced a more finely tuned variable valve timing system and improved lubrication via revised oil return paths and an electronic monitoring system.
The IMS was also improved. It received a stronger, larger bearing set than the majority of the M97 lineup. Unlike the M96, which used a weak dual-row bearing set or, later, a single-row set, the M97 used a significantly beefed-up single-row configuration. Upon engine testing, the new IMS setup showed significantly reduced failure rates, a trend also observed in real-world applications. However, it didn’t eliminate the problem completely.
Rear shot of a 2005 Porsche 911 CarreraPorsche
The bore-scoring issue was also improved but not solved. Porsche continued to use the infamous Lokasil cylinder liner material, which, as with the M96, would break down over time. The open-deck block design remained an issue as well, and block flex still cropped up during heavy use, especially in the 3.6- and 3.8-liter motor variations. Thermal cooling was improved but remains an issue.
Despite the improvements, Porsche was faced with a major problem. It became clear that the M96/M97 architecture was fundamentally flawed. The company decided that a new design was necessary.
Porsche’s Clean-Sheet Answer To The M97 Problem
2009 Porsche 911 Sport Classic flat-six engine shotBring a Trailer
Finally, the answer to Porsche’s prayers came onto the scene in 2009. The new mill was coined “9A1”, or “MA1” in some circles. Both the 997.2-gen Porsche 911 and the 987.2-gen Porsche Boxster received the new engine. The 9A1 powerplant addressed virtually every single problem with the M96/M97. For one thing, the 9A1 was built with a stronger, closed-deck block design. Porsche’s engineers eliminated the entire IMS system. Direct fuel injection replaced the older multipoint port injection setup.
Grey 2009 Porsche 911 Sport Classic frontPorsche
The 9A1’s lubrication and cooling systems were also completely different. The new engine used a crankshaft-driven oil pump rather than the intermediate shaft-driven pump found on the M96/M97. The 9A1 also ditched the pseudo-dry-sump system found in the older mill for a variable-demand pump that also boasted a much more effective scavenging ability, or ability to prevent oil starvation during heavy acceleration, braking, or cornering.
All of these factors worked together to give the 9A1 engine an excellent reputation for reliability. It was stronger, simpler, and more efficient than the M96/M97 engine. The result was a significantly lower overall failure rate. Now, Porsche buyers could stop worrying about inherent design flaws and focus more on normal engine stuff, such as oil changes and air filter replacements.
What Flat-Sixes Should You Actually Buy?
Rear shot of a 2009 Porsche 911 Carrera SBring A Trailer
After seeing what separates the three engines we’ve discussed today, let’s see which one you should actually buy for yourself.
M96 (1996-2008)
If we had to recommend one engine to avoid completely, it would be the M96. Of course, it’s not a guarantee that it would have awful bore scoring and IMS issues, but the chances are highest with the M96 engine. However, if you’re a fan of late-1990s and 2000s-era Porsches, you may have to go for it anyway and hope your ride doesn’t develop any engine problems. Remember, regular maintenance is your friend.
M97 (2005-2008)
In the middle sits the M97. It’s a large improvement over the M96, but it still suffers from many of the same issues as the M96. If you’re gunning for some sort of Porsche model with an M97 equipped, make sure you take a good look at its maintenance history. Look for anything related to the IMS or cylinder bore issues, and run away if something doesn’t feel right to you.
9A1/MA1 (2009-2016)
Obviously, if you can afford it, the 9A1/MA1 engine is the one you want. It doesn’t have an IMS at all, meaning it can never fail. Its block is stronger, its oiling system is better, and it’s regarded as one of Porsche’s most reliable engines built in the modern era.
With the introduction of the 9A1 and the subsequent canning of the M96/M97 engine, 2009 marked one of Porsche’s largest engineering turning points in the water-cooled era. It successfully showed the world that Porsche could engineer with the best of them and cemented the brand’s water-cooled prowess among enthusiasts.
Sources: Porsche, FCP Euro, PocketMags.com, Flat6Innovations.com.
