Rennvision on Porsche Bore Scoring: Updated Insights, Diagnostics, and Fixes

Jake Raby’s Rennvision channel has revisited and expanded its Porsche engine content with a renewed focus on Porsche bore scoring—integrating lessons learned since the 2018–2019 videos and the post-2020 period. This guide summarizes the series’ key takeaways and pairs them with proven repair strategies from Flat 6 Innovations and technical resources from LN Engineering.

Related resources: Rennvision: Focus On – Bore Scoring playlist   |  LN Engineering: Porsche Cylinder Bore Scoring

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What’s New Since the 2018–2019 Videos?

• Context: A 2021 update reframes prior bore-scoring content with fresh field data and refined procedures.
• Education-first: The series doubles down on clear diagnostics (proper borescope technique, cam deviation review) and realistic fixes.
• Community & membership: Viewers are encouraged to subscribe and consider paid learning for deeper technical dives.

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Bore Scoring 101

What it is: Longitudinal scoring of cylinder walls (common in M96/M97) that increases oil consumption, noise, and—if ignored—can lead to major engine damage.

Why it happens: A combination of factors: surface finish and coating behavior (Lokasil/Alusil), heat cycles and oil film management, piston skirt coating loss, fueling and injector condition, and operating patterns. No single cause explains every case; prevention and correct diagnosis are key.

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Fast Symptoms vs. Subtle Clues

What You Might Notice	What It Can Mean	Next Step
Ticking/knock from one bank (often Bank 2), hot idle	Possible skirt wear and wall scoring; noise may vary with load/temp	Stop hard use; schedule borescope from the sump side
Rising oil consumption, sooty tailpipe, smoke on start/overrun	Oil bypass from scored walls; ring sealing compromise	Compression/leakdown and visual cylinder inspection
No obvious noise, car “feels fine”	Scoring can still be present—especially on cylinders not visible from plug holes	Use correct borescope approach before assuming “all clear”

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Diagnostics That Actually Work

1. Borescope correctly (from the sump side): Many M96/M97 problem areas aren’t visible from plug holes. Use the proper angle and access points documented by experienced Porsche rebuilders.
2. Cut and inspect the oil filter; pull the sump plate: Look for metallic debris/glitter and document findings.
3. ECU interrogation: Review over-rev counters and camshaft deviation values for corroborating clues.
4. Fuel system check: Verify injector health and fueling (leak-down, spray pattern); poor fueling contributes to skirt/coating distress.
5. Operating profile review: Heat cycles, short-trips, extended oil intervals, and oil choice matter; adjust practices to slow progression.

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Prevention & Slowing Progression

• Oil strategy: Use the recommended high-quality oil and change on conservative intervals; monitor temps.
• Injector hygiene: Keep injectors clean/healthy; address fueling anomalies early.
• Driving patterns: Avoid chronic short-trips and babying; get the engine to full operating temperature regularly.
• Listen and log: Record sounds, oil use, and maintenance; consistent records help trend small issues before they grow.

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Proven Fixes When Scoring Is Confirmed

There is no “in-car” magic cure for true cylinder scoring. The durable repair is a full engine teardown with cylinder work and updated components. A widely used approach is to machine out the damaged material and install robust replacement cylinder sleeves (e.g., Nickies) along with updated pistons/rings and any model-specific upgrades discovered during inspection. Pair this with best-practice rebuild processes (checking IMS shaft/runout, timing components, oiling, and cooling system health).

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Rennvision Series Timeline (Key Milestones)

• 2018–2019: Initial bore-scoring videos establish fundamentals (inspection and failure modes).
• 2020: Pandemic disruptions pause normal cadence.
• Mid-2021: Update video announces refreshed and expanded content, integrating new shop data and procedures; encourages subscriptions and paid education for deeper learning.

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What to Do Next

If you suspect bore scoring—or you simply want to baseline your car—book a borescope inspection with a Porsche specialist who follows the sump-side method and can interpret results in context. If scoring is present, discuss a full, parts-validated repair plan rather than chasing temporary measures. For deeper training and case studies, subscribe to Rennvision, and for rebuild options, review Flat 6 Innovations and LN Engineering resources below.

More info: Rennvision – Bore Scoring (playlist)  | LN Engineering – Porsche Cylinder Bore Scoring  |  How to Borescope Your Porsche Engine

How to Identify a Failing IMS Bearing (M96/M97 Porsche)

Worried about the intermediate shaft on your 986/987 Boxster or 996/997 911? This guide explains how to identify a failing IMS bearing, what warning signs really matter, and the diagnostic steps shops use before recommending repair. Links to IMS Retrofit and the IMS Solution are included for next steps.

Related resources: Identifying & Fixing the Porsche IMS Bearing Problem  |  IMS Pre-Qualification

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Why IMS Bearings Fail

The factory sealed ball bearing isolates the IMS from fresh oil. As seals age, oil can enter but not circulate freely, leading to marginal lubrication, rising friction, and accelerated wear. Heat cycles, extended oil intervals, and load/vibration further increase risk.

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Real-World Symptoms (and Non-Symptoms)

Signal	What It Means	Action
Metal debris in oil filter	Particulate escapes once the bearing seal is breached; debris in filter/sump is a late warning sign.	Stop driving; perform full pre-qualification and plan repair.
Glitter or fragments in sump	Wear material collects in the sump even when the filter looks clean.	Remove sump plate and inspect closely; treat as active failure risk.
Rattling/whine from rear of engine	Some dual-row bearings may make noise before failure; single-row often do not.	Investigate immediately; do not rely on sound alone.
No noise, no debris	Can still be failing—single-row bearings frequently fail without early warning.	Use pre-qualification diagnostics rather than assumptions.

Note: Oil analysis (UOA) typically cannot “catch” IMS debris—particles are larger than UOA test ranges. Clean filters do not guarantee health.

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How to Identify a Failing IMS Bearing: A Practical Checklist

1. Cut and inspect the oil filter. Any metallic debris or flakes are red flags. Document with photos.
2. Pull the sump plate. Check for glitter, chips, or sludge; debris often settles here even if the filter looks clean.
3. ECU interrogation (Durametric/Piwis). Review fault codes, over-revs, and camshaft deviation values; excessive deviation can indicate timing component wear.
4. Borescope the cylinders from the sump side. On M96/M97, bore scoring starts where plug-hole scoping won’t see it. Do not skip this step.
5. Crankcase manometer test. Confirms AOS function and overall breathing; abnormal readings can correlate with internal wear/contamination.
6. RMS bore inspection during trans-out work. Check for crankshaft runout/“sag” that may masquerade as RMS leaks and complicate IMS service timing.
7. Road test & noise check. Listen at hot idle and light load, but remember: lack of noise ≠ healthy IMS, especially on single-row designs.

These steps form the pre-qualification process used by experienced Porsche shops before recommending an IMS repair path.

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When Should You Check?

• Before buying an affected 1997–2005 car (serviceable IMS), or any time history is unknown.
• At clutch/RMS service time—with the transmission out, inspection access is best and labor is shared.
• After track events or heat cycles that could accelerate wear.
• On higher-mileage cars (or low-miles/short-trip cars that sit)—both scenarios can be risky.

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What to Do If You Suspect IMS Trouble

If debris is present—or if pre-qualification findings are concerning—plan a repair path instead of continuing to drive. Two widely used options:

IMS Retrofit

• What it is: Ceramic-hybrid ball-bearing retrofit that eliminates grease seals so engine oil can lubricate the bearing.
• Best for: Cost-sensitive owners who accept a service interval and want an upgrade aligned with clutch work.
• Learn more: IMS Retrofit

IMS Solution

• What it is: An oil-fed plain bearing (no rolling elements) riding on a pressurized oil film, designed as a permanent fix.
• Best for: Long-term keepers who prefer no planned service interval and OEM-style lubrication principles.
• Learn more: IMS Solution

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FAQ: Identifying a Failing IMS Bearing

Can a single-row IMS fail without warning?

Yes. Many single-row failures show no noise and no early debris before a sudden event. That’s why pre-qualification is so important.

Is used-oil analysis enough to screen for IMS wear?

No. IMS wear particles are generally larger than UOA test ranges. Use filter/sump inspection instead.

If my filter is clean, am I safe?

Not necessarily. Debris can sit in the sump or a bearing can be failing silently. Follow the full checklist.

When’s the best time to inspect or replace?

During clutch or RMS service, because access labor overlaps—and you can address multiple items at once.

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More info: LN Engineering  |  IMS Pre-Qualification  |  IMS Retrofit  |  IMS Solution

IMS Bearing Replacement Costs: What to Budget and How to Choose Between IMS Retrofit and IMS Solution

If you own a 1997–2008 Porsche Boxster, Cayman, or 911 with an M96/M97 engine, planning for ims bearing replacement costs is smart preventative maintenance. A proactive IMS service typically runs $1,500–$3,000 installed (parts + labor), which is far less than the cost of an engine rebuild after a failure.

Related resources: IMS Bearing Replacement Costs Guide (LN Engineering)  |  IMS Retrofit  |  IMS Solution

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IMS Bearing Replacement Costs (Typical Ranges)

Most owners see totals in this range, depending on model, transmission, shop rate, and bundled services:

Service Package	What’s Included	Typical Installed Cost
IMS Retrofit only	IMS Retrofit kit (ceramic hybrid ball bearing), labor to access and replace	$1,500–$2,300
IMS Retrofit + clutch + RMS	Add clutch components and rear main seal while transmission is out	$1,900–$3,000+
IMS Solution (oil-fed plain bearing)	Permanent, oil-fed plain-bearing kit; similar labor time, higher parts cost	$2,200–$3,500+ (varies by model and add-ons)

Note: Tiptronic/automatic models can add labor; regional shop rates and parts selection also affect totals.

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What Affects IMS Bearing Replacement Costs?

1. Labor time & transmission type – Manual cars typically require transmission removal; some Tiptronic cars may need the engine/trans removed as a unit.
2. Parts choice –
   • IMS Retrofit (ceramic hybrid ball bearing) generally has the lower parts cost but includes a service interval (often 6 years / 75,000 miles).
   • IMS Solution (oil-fed plain bearing) has a higher initial parts cost, but is engineered as a permanent fix with no planned service interval.
3. Bundled “while you’re in there” items – Common add-ons: clutch, RMS, air-oil separator, water pump, dual-mass flywheel (DMF), fluids/filters.
4. Pre-qualification & inspection – Verifies the engine is a good candidate; findings can change scope and cost before work begins.
5. Tools & logistics – Access to the right fixtures and rental tools keeps labor predictable.

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Choosing Between IMS Retrofit and IMS Solution

IMS Retrofit (Service-Interval Approach)

• What it is: A ceramic-hybrid ball-bearing upgrade designed to be oil-lubricated in service.
• Why owners choose it: Lower up-front parts cost; an effective upgrade when paired with a clutch service.
• Service interval: Commonly 6 years / 75,000 miles (confirm for your specific kit).
• Learn more: IMS Retrofit

IMS Solution (Permanent, Oil-Fed Plain Bearing)

• What it is: An oil-fed plain bearing that rides on a pressurized oil film (like crank bearings), eliminating rolling elements.
• Why owners choose it: No planned service interval; engineered for the life of the engine—ideal for long-term ownership.
• Warranty: Limited warranty terms vary by application; review details at the official site.
• Learn more: IMS Solution

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Best Time to Schedule IMS Service

The most cost-effective time for ims bearing replacement is during a clutch or RMS job. With the transmission already out, you avoid duplicate labor and can bundle other preventative items.

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Cost-Saving Tips

• Bundle smart: Combine IMS with clutch and RMS while the transmission is out.
• Confirm your current setup: If the car already has an IMS upgrade, check the install date/mileage and applicable service interval.
• Pre-qualify: A quick inspection prevents installing a new bearing into a compromised engine.

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FAQ: IMS Bearing Replacement Costs

What’s the main cost difference between IMS Retrofit and IMS Solution?

Parts cost is the big swing. IMS Retrofit kits are typically lower priced up front but have a service interval. The IMS Solution kit costs more initially but is designed as a permanent oil-fed fix with no planned interval. Labor time is broadly similar because access steps overlap.

Why do some quotes exceed $3,000?

Higher regional shop rates, extra labor for Tiptronic models, and bundling of clutch/RMS/DMF, etc., can push totals above the usual window—but bundling often saves money over the long term by avoiding duplicate labor.

Do I really need pre-qualification?

Yes. Pre-qualification confirms your engine is a candidate for the work and helps avoid installing new parts into an engine that’s already experiencing damage.

Is waiting OK if my car shows no symptoms?

A clean filter and quiet engine aren’t guarantees. Planning a proactive IMS service—ideally aligned with clutch or RMS work—helps avoid unpredictable and costly failures.

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Bottom Line

Budget $1,500–$3,000 for most ims bearing replacement costs on affected Porsche models. Choose IMS Retrofit for lower up-front parts cost with a planned service interval, or step up to the IMS Solution for a permanent, oil-fed approach with no planned interval. Either strategy is far cheaper—and far less stressful—than a post-failure engine rebuild.

More info: LN Engineering  |  IMS Retrofit  |  IMS Solution

High-Mileage 996 Case Study: Why a Porsche IMS Bearing Replacement Can’t Rely on “No Debris, No Noise”

 

Porsche IMS Bearing Replacement: A Hidden-Failure Case Study from a High-Mileage 996

A inspection of a 2003 Porsche 996 (135,000 miles) by Tony Callas, of Callas Rennsport, offers a cautionary tale for anyone weighing a porsche ims bearing replacement. Despite a clean oil filter, debris-free sump, normal cam timing, and no audible bearing noise, teardown revealed severe internal wear and pitting inside the IMS bearing race. The technician declined to install a standard drop-in bearing and chose an alternative path, underscoring a key reality: external checks can look perfect while the IMS is quietly failing.

What the Inspection Found (and Didn’t)

• No external red flags: Oil filter and sump were free of glitter/metal; timing components looked normal; the engine was quiet.

• Internal truth: Once removed, the IMS bearing showed heavy race pitting and wear—damage that can precede catastrophic failure.

• Outcome: A conventional replacement bearing was deemed inappropriate given the condition; an alternative IMS strategy was pursued.

Why This Matters for Porsche IMS Bearing Replacement

1. Silent progression: IMS bearings can deteriorate without noise or shed metal late in the process. Relying on sound, filter checks, or sump inspections alone can be misleading.

2. High mileage = higher risk: At 135k miles, this bearing had significant subsurface damage. Aging grease, marginal lubrication history, heat cycles, and mixed loading all accelerate wear.

3. Fit the solution to the condition: Not every engine is a candidate for a simple bearing swap. The observed race pitting suggests some cars warrant more robust, oil-fed or otherwise engineered solutions designed for mixed radial/thrust loads and long-term reliability.

Practical Guidance for Owners & Shops

• Do not assume “no debris = healthy.” Clean filters and quiet operation do not rule out internal race damage.

• Use the clutch window. If the transmission is out for clutch or RMS work, it’s the most cost-effective time to plan a porsche ims bearing replacement.

• Choose the design for the duty. Consider solutions that address lubrication and thrust loading—not just material upgrades.

• Document and baseline. Record findings (photos of the bearing/race), update maintenance logs, and, if applicable, add used-oil analysis going forward.

Signs You Shouldn’t Ignore

• Any prior IMS service of unknown type or age

• Ownership plans that involve long-term keeping of the car

• Elevated mileage or track use/heat cycles

• Intermittent oil pressure or temperature anomalies

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Quick Takeaways

• A 996 can present no noise and no glitter yet hide advanced IMS race pitting.

• Visual and acoustic checks alone aren’t definitive; direct bearing evaluation is the gold standard.

• Some cars are poor candidates for a “standard” swap; a more engineered IMS solution may be the safer choice.

How to choose a Porsche IMS Bearing Replacement

Porsche IMS Bearing Replacement: What Fails, What Works, and Why It Matters

For owners of M96 and early M97 engines, the intermediate shaft (IMS) bearing is a known weak point. The factory part used a sealed, grease-packed ball bearing isolated from engine oil. As the seal ages, oil seeps in and washes out the grease—but the degraded seal still restricts oil flow. The result is marginal lubrication, rising friction, and accelerated wear that can end in bearing failure. That’s why a timely Porsche IMS bearing replacement is considered essential preventative maintenance on affected models.

What Went Wrong with the Original Sealed Bearing

• Sealed design: Intended to keep contaminants out, the seal kept fresh oil out as well.

• Aging seals: Once the seal degrades, oil enters, dilutes or removes the grease, and then struggles to circulate.

• Poor lubrication: With limited fresh oil exchange, the bearing operates on a thin, unreliable film that can break down under load and temperature.

Replacement Paths Owners Consider

Open Ceramic Hybrid Ball Bearings

• Pros: Reduced friction, better heat characteristics, direct oil access.

• Cons: Still a rolling-element bearing in a mixed-load environment; long-term durability varies by use and service conditions.

Roller Bearings

• Pros: Strong radial load capacity.

• Cons: The IMS sees both radial and thrust (axial) loads; rollers aren’t ideal for sustained thrust loads, making them a compromise in this application.

Porsche’s Ceramic Hybrid Service Part (Sealed)

• Pros: Material upgrade over stock.

• Cons: Retains the sealed architecture, so the fundamental lubrication limitation remains.

Why a Plain Bearing (Oil-Fed) Solution Stands Apart

A plain bearing rides on a pressurized oil film—the same principle used in crankshaft main and rod bearings. With the right oil supply, metal surfaces never touch, dramatically reducing wear. In the IMS location, this approach directly addresses the two core issues with the original design: inadequate and inconsistent lubrication and a mixed radial/thrust load profile.

Key benefits:

• Pressurized lubrication prevents metal-to-metal contact.

• Load handling suits the IMS’s combined radial/axial forces.

• Service life: Designed as a long-term fix rather than a periodic replacement.

When to Consider Porsche IMS Bearing Replacement

• Preventative service on affected engines during clutch work or rear main seal service (labor overlap).

• Evidence of bearing distress (noise, metal debris in filters or oil analysis).

• Ownership horizon: If the vehicle is a long-term keeper, opting for a solution that solves lubrication at the root is often preferred.

Practical Tips for Owners and Shops

• Plan it with a clutch: Most labor-efficient time to perform a Porsche IMS bearing replacement is during a clutch job.

• Oil and filters: Follow conservative oil change intervals and use quality filtration; consider used-oil analysis for early warning.

• Document everything: Keep parts receipts, installation notes, and mileage; it helps resale value and service history.

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Quick Takeaways

• The factory sealed ball bearing isolates the IMS from engine oil; once the seal degrades, lubrication remains marginal and failure risk rises.

• Open ceramic hybrids and rollers improve oil access but don’t fully address the IMS’s mixed load profile—especially thrust loads.

• An oil-fed plain bearing leverages a pressurized film (like crank bearings) to virtually eliminate metal contact and wear, making it the most robust engineering approach for the IMS location.

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FAQs: Porsche IMS Bearing Replacement

Is Porsche IMS bearing replacement always necessary?
On affected engines, it’s a widely recommended preventative measure—especially if clutch work is already planned.

Which replacement style lasts the longest?
Designs that provide pressurized oil-film lubrication and are engineered for combined radial and thrust loads typically offer the strongest durability story for IMS duty.

Will a ceramic hybrid ball bearing fix the problem?
It’s an upgrade over stock materials, but if the design remains sealed, it does not fully resolve the lubrication limitation that drives the failure mode.

Are roller bearings better than ball bearings for IMS?
Not necessarily. While rollers handle radial loads well, the IMS also experiences thrust loads, which rollers don’t manage as effectively.

What’s the best time to do a Porsche IMS bearing replacement?

During a clutch replacement—you’ll save labor and downtime.