The Real Reason Porsche IMS Bearings Fail—And How to Stop It

Porsche is a German sports-car and performance-car brand known for engineering-focused drivetrains and a strong enthusiast community. In this segment, it sets the context for the episode’s focus on Porsche ownership questions and known model issues.

Charles Navarro is the founder of LN Engineering, a specialist Porsche-focused shop. In this segment, he’s positioned as an expert because LN Engineering is known for addressing IMS bearing issues on certain Porsche engines.

LN Engineering is a Porsche-focused engineering company founded in the early 2000s. It’s described here as being especially associated with solutions for IMS bearing issues on certain Porsche models.

“IMS bearing” refers to the intermediate shaft bearing used in certain Porsche flat-six engines. The “IMS bearing issues” are a well-known reliability concern because bearing wear or failure can lead to serious engine damage, which is why specialist fixes and preventative measures exist.

CNC equipment is computer numerical control machinery used to precisely cut or shape parts. In the context of LN Engineering’s origin story, it’s how they could manufacture components accurately while working on their projects.

VW forums are online communities focused on Volkswagen vehicles, where owners share technical knowledge, troubleshooting, and project updates. The speaker credits forum discovery and networking as part of how their work gained early customers.

“Water cool” here refers to water-cooled engine designs, meaning the engine uses a liquid coolant circuit to manage temperature. It contrasts with the older air-cooled Porsche philosophy that some enthusiasts prefer.

Pelican Parts Forum is a long-running Porsche enthusiast message board where owners discuss technical issues, maintenance, and aftermarket solutions. The speaker references it to explain Jake’s screen name and the community context around Porsche culture.

“No H20” is a screen-name reference to water (H2O), used here to signal a preference for air-cooled Porsche purity. It reflects an enthusiast debate about whether water-cooled engines are “real” Porsches.

Bruce Anderson is described as a leading authority on air-cooled Porsche 911s—writing books, teaching classes, and contributing to Porsche media. In the segment, he’s also the catalyst for the host to start working on water-cooled Porsche engines.

The Porsche 911 is the iconic rear-engine sports car, and the “air-cooled” versions are a major part of its enthusiast history. In this segment, the host connects Bruce Anderson’s expertise to the air-cooled 911s before the brand moved to water-cooled engines.

M96 is the engine family code used for the first water-cooled Porsche 911 generation, the 996. The hosts explain that M96 was used when the first 911 water-cooled version came out in 1999, and they’re discussing whether these engines are truly “disposable” or can be made into a great ownership experience.

M97 is the later engine family code that followed M96 for Porsche’s early water-cooled era. The hosts say M97 came “after a few years,” and they’re focusing on these engines because many people online treat them as disposable.

In this context, “disposable” is an enthusiast shorthand for an engine that many owners believe is not worth rebuilding—either because failures are common or because repairs are perceived as impractical. The hosts use it to frame the internet narrative they want to challenge about M96/M97 engines.

The Porsche 986 Boxster is the first-generation Boxster (late 1990s) that used an air-cooled-era Porsche approach but with a more modern layout for its time. Here it’s mentioned as another common “first Porsche,” where owners moving from brands like Toyota or Honda may underestimate long-term maintenance costs.

Deferred maintenance means postponing scheduled repairs or upkeep until later. The host argues that many first-time Porsche buyers don’t set aside money for it, which can turn manageable issues into expensive problems.

Valve adjustment (“adjust valves”) is a periodic service where clearances are set to keep the engine running correctly. The host contrasts older air-cooled Porsches—where this was expected—with later models that were marketed as requiring less frequent valve work.

“Change belts every 12,000 miles” refers to a very frequent timing-belt replacement interval that was part of the ownership experience on some older Porsche designs. The host uses it to illustrate how later cars were marketed as less demanding during the warranty period.

An “emissions issue” is a regulatory or engineering problem related to how much pollution a vehicle produces. In this segment, it’s one of the proposed reasons Porsche moved to water cooling—because emissions rules can force changes in engine design and temperature management.

An air-cooled engine relies on airflow over the engine’s fins to remove heat, rather than using a liquid coolant system. The segment argues that tightening emissions rules made Porsche’s air-cooled approach harder to meet. It also contrasts air-cooled design with later water-cooled engines where lubrication and internal bearing design differ.

Pressurized oil is engine oil delivered under pressure to lubricate and support internal bearings. The segment explains that the original engine layout didn’t provide pressurized oil to support a plain bearing on one side of the intermediate shaft. That lubrication limitation is presented as a key reason the IMS-bearing problem exists.

A plain bearing (also called a journal bearing) is a sliding bearing surface that relies on an oil film to prevent metal-to-metal contact. In this segment, the issue is that the engine design didn’t provide pressurized oil to support that plain bearing location. Without proper oil support, wear risk increases.

A ball bearing uses rolling elements (balls) to reduce friction compared to sliding bearings. The segment contrasts a plain bearing location with a ball bearing location for the intermediate shaft. The lubrication and design differences between these bearing types are part of why the IMS discussion matters.

A dual-row bearing has two rows of rolling elements, which can increase load capacity and durability compared with a single-row design. The segment says that when the 986 and 996 came out, Porsche used a dual-row bearing for the IMS. That’s presented as a design change from earlier lubrication/architecture constraints.

An angular contact bearing is designed to handle combined radial and axial loads, with the contact angle helping control thrust forces. The segment claims Porsche used a custom angular contact bearing for the IMS that “you can't buy anywhere,” implying a bespoke design tailored to that engine’s packaging and loads. Custom parts can also be more expensive and harder to replace.

An intermediate shaft bearing supports the intermediate shaft in a Porsche engine. When it fails, the shaft can lose proper alignment and lubrication, which can throw off the timing between the crankshaft, camshafts, and valves.

Plane bearings (plain bearings) are bearing surfaces that rely on an oil film to separate the rotating shaft from the stationary bearing material. If lubrication is lost, the surfaces can overheat and seize, leading to catastrophic damage.

Hydrodynamic lubrication is when a pressurized oil film fully separates two moving metal surfaces. The oil film prevents direct metal-to-metal contact, so the bearing can spin without welding itself together.

An oil film is the thin layer of lubricant that sits between bearing surfaces during operation. Its job is to prevent metal-to-metal contact; without it, friction spikes and the bearing can fail rapidly.

Engine oil is the lubricating fluid that reduces friction and carries heat away from moving parts. Here, the host explains that if the grease seal were left off, engine oil could lubricate the bearing, improving durability.

A single row bearing uses one row of rolling elements to carry loads. The host argues Porsche switched to a single row intermediate shaft bearing (instead of a dual row), which reduced load-carrying capacity and led to much higher failure rates.

A “6204 bearing” is a specific bearing size/type designation (6204 is a common deep-groove ball bearing family). The host notes it’s widely used in other applications, which is part of the argument that Porsche chose a cheap, readily available bearing for the intermediate shaft.

An alternator bearing is the bearing that supports the alternator’s rotating shaft. The host uses this as an analogy: the same bearing type Porsche used is also used in alternators, implying it’s common and proven elsewhere.

Load carrying capacity is the maximum force a bearing can handle while maintaining acceptable wear and life. The host claims switching to the single row design cut this capacity roughly in half, which helps explain the jump in failure rate.

A class action lawsuit is a legal case where many affected people join together as a group. The host suggests that without this class action, Porsche wouldn’t have been forced to provide the failure-rate numbers that enabled the analysis.

“Serial numbers” are unique production identifiers used to track parts and assemblies. In this segment, the hosts discuss how online “serial number” charts claim to predict which bearing a car has, but they say the real-world mapping is inconsistent.

An “engine serial number” is a unique identifier stamped/recorded for a specific engine. The hosts explain that earlier Porsche documentation tied the engine serial number to the car, but for the 986/996 era that recordkeeping stopped, so you can’t always verify which engine went into which chassis.

“Air cooled cars” refers to vehicles whose engines rely primarily on airflow over the engine to manage heat, rather than using a liquid coolant system. The hosts tie this to Porsche’s earlier documentation practices for those air-cooled-era cars.

The Porsche Boxster S is a mid-engine roadster where the engine layout makes certain internal components—like intermediate-shaft bearings—important to understand for long-term ownership. The speaker uses their 2005 Boxster S as an example of when the bearing design may have changed.

The Porsche Cayman (987) is a mid-engine Porsche coupe, and the speaker claims it consistently uses the “bigger bearings” compared with other 987-era variants. This is used to explain why some models are easier to predict than others when assessing which bearing design is present.

This refers to failures or wear of the intermediate shaft bearing in Porsche flat-six engines. When the IMS bearing goes bad, it can cause metal debris and mechanical damage that may require major engine work.

Sleeving blocks is an engine-rebuilding technique where new cylinder liners are installed inside the engine block. It’s often used to restore cylinder dimensions when there’s wear or scoring, and it can be part of addressing deeper cylinder damage.

RMS typically refers to the rear main seal in Porsche engines. A failing RMS can cause oil leaks at the back of the engine, and depending on severity, it may require significant disassembly to replace the seal.

Finding metal in the oil filter is a sign that internal components are shedding material. In this context, it’s presented as an early warning for IMS bearing wear before a total failure.

“Letting it sit” refers to leaving a car unused for long periods. The host argues this is especially bad for these Porsches because seals can degrade and leak over time, and the IMS bearing discussion is tied to how the car is used.

Seals are rubber or elastomer components that keep fluids from escaping. The host claims that when a car sits, seals can deteriorate and begin leaking, which is a common aging/storage-related issue.

“996s” refers to the Porsche 911 generation known as the 996 (the late-1990s/early-2000s 911). In this segment, they’re discussing a known Porsche 911 IMS-related issue and preventative work done by a dealer.

IMS stands for Intermediate Shaft, a component in the Porsche 911’s engine/transaxle layout. The “IMS issue” refers to failures or wear in the IMS bearing area, which can lead to expensive engine damage if not addressed.

Pushrod engines are engines that use pushrods to transfer motion from the camshaft to the engine’s valves. In this segment, the host links pushrod-engine oil behavior to failures seen on dynos during the early 2000s oil formulation changes.

“Oil being reformulated” means the chemical formulation of engine oil was changed. The host claims that these changes contributed to engine failures on dynos for some pushrod engines until the cause was understood.

Silicon nitride is a ceramic material known for being extremely hard and wear-resistant. In this segment it’s discussed as a bearing/lifter material that could handle harsh conditions and even be used in experiments running on vegetable oil. The host also links its use to military applications because it’s “pretty much indestructible.”

Vegetable oil is a fuel alternative to conventional petroleum diesel. The segment uses it as a proof-of-concept that the material and lubrication/compatibility of the engine components could tolerate non-standard fluids. It’s not a typical everyday fuel choice for most cars, but it illustrates the durability angle of the materials being discussed.

A ceramic component is a part made from ceramic rather than metal, often chosen for hardness and wear resistance. Here it’s used to explain thermal behavior: ceramics can reduce heat transfer compared with metal-on-metal contact, helping manage temperatures in a bearing system. The host still notes that races (the ring surfaces) can wear even if the rolling elements are ceramic.

In this context, “hybrid” describes a bearing design that mixes materials—using ceramic where it helps most, while keeping other parts (like races) in a more practical material. The host frames it as a cost/benefit compromise versus a fully ceramic bearing. The goal is to get durability improvements without the very high per-bearing cost.

A service interval is a scheduled mileage/time period when maintenance (like inspection or replacement) is expected. The host contrasts a ball bearing approach that requires periodic service with the plain-bearing IMS solution described as “permanent.” In other words, one strategy expects wear and plans for it; the other aims to eliminate the need for routine replacement.

An IMS retrofit kit is an aftermarket (or upgraded) solution designed to address the known IMS bearing lubrication/failure concerns by replacing or modifying the bearing setup. The segment references a kit that supplies bearings without seals and a system that can be pressure-fed.

The IMS flange is the mounting interface on the engine that covers and locates the intermediate shaft bearing assembly. Removing it (as described in the segment) allows access to the bearing and its seals/grease so oil can reach the bearing properly.

Pressure-fed oil is lubrication delivered under oil pressure rather than by passive splash or gravity. The segment describes a system that routes pressurized, filtered oil to the IMS bearing via an external oil line, improving lubrication consistency and reducing reliance on the original bearing design.

A spin-on filter adapter is a hardware piece that lets you connect a spin-on oil filter setup into the engine’s oil circuit. In this segment, it’s used as part of the patented system to pull oil from the filtered side and route it to the IMS bearing.

An external oil line is an oil hose/pipe routed outside the engine to deliver oil to a specific component. The speaker says the system uses an external oil line to send pressurized, filtered oil to the IMS bearing.

An oil pressure gauge measures the engine’s oil pressure, which indicates whether the lubrication system is delivering oil effectively. The speaker notes the IMS upgrade requires only a very small amount of oil, so it shouldn’t noticeably change readings on an oil pressure gauge.

IMS stands for Intermediate Shaft, and the “IMS solution” refers to an aftermarket or service approach to address IMS bearing issues. In this context, it’s a fix that involves sleeving/servicing the IMS bearing area so owners can rebuild with less worry about future failure.

A non-serviceable bearing is one that isn’t designed to be replaced through normal maintenance. In many Porsche engines discussed by enthusiasts, the IMS bearing can be either serviceable or non-serviceable depending on the design. The host argues that owners should avoid unnecessary rebuilds when the bearing is non-serviceable but not actually failing.

A go-no-go tool is a simple inspection gauge used to quickly verify whether a part meets a tolerance. In this segment, the host says Porsche created a go-no-go tool to check alignment between the crankshaft and a hole in the engine case. If the tool indicates a mismatch, it can point to a machining/alignment defect that affects sealing.

The crankshaft is the main rotating shaft inside the engine that converts the up-and-down motion of the pistons into rotational motion. Many oil seals (like the rear main seal) are designed specifically to seal around the crankshaft where it passes through the engine housing. That’s why crankshaft-related sealing issues are often discussed together with clutch/flywheel work.

The rear main seal is the seal at the back of an engine crankshaft that prevents engine oil from leaking out where the crankshaft exits the engine block. If it “weeps” or leaks, oil can contaminate the clutch/flywheel area and create mess or drivability concerns. It’s often addressed when the engine/transmission is already apart.

A dual mass flywheel (DMF) is a flywheel assembly with two rotating masses connected by springs/dampers to smooth out engine vibration and reduce driveline harshness. The speaker argues that the DMF’s mass/weight could contribute to rear main seal leaks, though they counter that many engines use DMFs. DMFs are commonly involved when you do clutch or transmission work.

PTFE (polytetrafluoroethylene) is a plastic material used for seals because it can be chemically resistant and wear well. The speaker says Porsche redesigned the rear main seal using a Teflon/PTFE seal, aiming to improve durability compared with earlier designs. Proper installation is critical because the seal can be damaged or installed incorrectly.

The speaker groups Porsche Boxster and Cayman models as also having rear main seal (RMS) issues. These are Porsche’s mid-engine sports cars, and the RMS is still a crankshaft-area seal that can leak and require drivetrain access to fix. The mention is mainly to broaden the RMS issue beyond just the 911.

The oil pan is the reservoir at the bottom of the engine that holds the engine oil. During an oil change, people sometimes inspect the pan for metal particles as a clue to internal wear or bearing failure.

“Oil fed” describes a bearing design that receives lubrication from the engine’s oil system. In this discussion, the speaker contrasts different IMS bearing kit types—one described as oil-fed—because lubrication method affects how the bearing is engineered and serviced. It’s part of why different kits can have different costs.

Preventative maintenance is proactive work done to reduce the chance of failures before they happen. Here, it’s framed as addressing not just the IMS bearing, but other engine-related issues while the engine is already being opened up. The idea is to minimize the odds of needing a second major teardown later.

A clutch is the friction device that connects and disconnects the engine from the transmission. When the car is already being disassembled for IMS bearing work, the clutch may be replaced “while you’re in there” if it’s worn or due. This is a common strategy to avoid paying for the same labor twice.

RMS seal typically refers to the rear main seal, which seals the engine’s crankshaft at the rear of the engine. It’s mentioned here because it sits in the area exposed during major engine/transmission work, making it a common “while you’re in there” replacement. Replacing a leaking RMS seal can prevent oil leaks and contamination.

An air oil separator (AOS) is part of the crankcase ventilation system that separates oil mist from blow-by gases so it doesn’t get sucked into the intake. On some Porsche flat-six engines, a failing AOS can contribute to vacuum/air leaks and oil consumption-related issues.

AOS vent lines are the hoses/tubes that route crankcase ventilation flow to and from the air oil separator. When these plastic corrugated tubes age and crack, they can create unmetered air (a vacuum leak), which upsets fueling and can worsen running conditions.

A vacuum leak is an unintended opening that lets outside air enter the intake/vacuum system, bypassing the engine’s normal air/fuel measurement. The engine then often interprets the mixture as too lean and compensates by adding more fuel.

“Five chain engines” refers to certain Porsche flat-six engines that use a multi-chain timing system rather than a simpler single-chain layout. This architecture is associated with specific wear points, including components that guide/actuate variable cam timing.

The vario cam solenoid is an oil-pressure-actuated control valve used to vary camshaft timing. In these engines, it works with the timing chain system and relies on wear surfaces/pads; when those wear, timing deviation can increase.

Variable cam timing changes when the camshafts open the valves, allowing the engine to optimize torque and efficiency across different RPM/load conditions. In the discussed Porsche “five chain” setup, it depends on chain-guided components and wear pads that can degrade over time.

A durometric test measures material hardness (often used on plastics or elastomers) to assess wear/condition of components. Here, it’s referenced as a way to evaluate the wear pads/guides related to the variable cam timing system.

Camshaft deviation is the measured difference between commanded and actual camshaft timing. In these Porsche engines, excessive deviation (the speaker cites over 4%) indicates worn wear pads/guides in the variable cam timing mechanism and can precede more serious timing/chain issues.

An ICP process (inductively coupled plasma) is a lab method used to measure concentrations of metals in oil, which can indicate wear. The speaker contrasts it with other particle-size approaches and notes different detectable ranges.

Micron (µm) is a unit of length used to describe the size of particles in oil analysis. Smaller micron ranges can detect finer debris, which affects how well a given test can reveal early wear.

The RDE process is a specific oil-analysis method referenced by the speaker as using a different measurement approach. The key takeaway in context is that different lab methods can report different detectable ranges, so results aren’t directly comparable.

Oil analysis is a lab test of used engine oil to look for wear metals, contaminants, and other clues about what’s happening inside the engine. By comparing results over time, you can catch problems early—often before the driver notices symptoms.

Bore scoring is damage to the cylinder wall (the “bore”) where the piston rings slide. It can increase oil consumption and reduce compression, and it’s a sign of abnormal wear that may be detectable via oil analysis before symptoms show up.

Main bearings support the crankshaft in the engine block, while rod bearings connect the crankshaft to the connecting rods. When these bearings wear, they shed metal into the oil, which oil analysis can detect before severe damage occurs.

Porsche is referenced here as the kind of car whose engine condition can be monitored proactively using oil analysis. The key idea is that wear indicators like bore scoring and bearing wear can show up in oil data before obvious symptoms appear.

An injector issue means the fuel injector(s) aren’t delivering fuel correctly—such as leaking, dribbling, or producing poor spray patterns. On modern engines, injector problems can lead to fuel dilution of the oil and accelerated wear.

A bore scope is a small inspection camera used to look inside an engine’s cylinders. It can reveal physical signs like scoring, deposits, or evidence of leaking injectors that you can’t easily see from the outside.

Fuel dilution amount is the percentage of fuel mixed into the engine oil, usually caused by incomplete combustion or leaking injectors. Higher fuel dilution thins the oil and reduces lubrication, which can accelerate wear of bearings and cylinder walls.

GMC is mentioned as an example of the general idea that any engine can develop problems. The host’s point is that even a “good truck” can still have engine wear or issues that you’d want to monitor.

“Thermal reactors” were emissions devices used on some older air-cooled Porsche 911s to reduce pollutants. They can contribute to higher engine temperatures and are often cited as part of the “known issues” list for those cars.

This refers to a known failure involving the cylinder head “studs” on certain air-cooled Porsche engines—specifically a case where the studs could snap. It’s brought up as an example that even classic Porsche engines had real, identifiable weak points.

“Right to repair” is the policy and practical ability for independent shops and owners to access the information, parts, and tools needed to service modern vehicles. The host argues it’s becoming a bigger issue because newer cars can be harder to work on without manufacturer support.

Jiffy Lube is a well-known quick-service oil-change chain in the U.S. The host mentions it as an example of the kind of local shop that might be affected when cars become harder to service.

The Porsche Panamera is Porsche’s four-door performance sedan, built around the idea of using Porsche-level handling with everyday practicality. It’s mentioned here as an example of a modern Porsche that makes routine maintenance harder, specifically oil-level checking.

Oil level is the amount of engine oil in the crankcase, and it’s critical because too little oil can lead to engine damage. The speaker’s point is that some newer cars don’t make it easy to check oil level yourself (for example, by removing or limiting traditional dipstick access).

Dura-Metric is a diagnostic/maintenance tool brand used by DIYers and shops to perform certain service tasks on specific vehicle systems. Here it’s mentioned to explain that some tools only work up to certain model years, so owners may lose the ability to do services themselves on newer cars.

“Out of warranty” means the car is past the period where the manufacturer covers repairs for defects. The speaker is arguing that once warranty coverage ends, the cost of ownership and repairs can rise sharply—especially on newer cars with more complex systems.

Bore spraying refers to a cylinder-bore related failure mode where the engine’s internal surfaces are damaged, often discussed alongside other 996-era engine concerns. The term is used here as part of a list of serious repairs, implying it’s an expensive problem compared with routine maintenance.

The Porsche Macan is Porsche’s compact luxury SUV, known for its sporty driving feel and turbocharged engines. In this segment, it’s mentioned in the context of a specific engine-cylinder wear issue (“bore scoring”), which is the kind of ownership risk enthusiasts care about.