Toyota 86 ZN8: common faults & what to check

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The FA20D engine in the ZN6 86 does not feature an oil baffle plate or dry sump, leaving the oil pickup exposed to oil surge starvation during sustained high-G cornering on track. Oil shifts away from the pickup under lateral load, momentarily starving the connecting rod bearings of lubrication. Repeated oil starvation events cause accelerated bearing wear and can lead to catastrophic rod bearing failure or complete engine seizure. This is primarily a concern for cars with track history, hillclimb use, or spirited mountain road driving. Toyota's own track day advisories acknowledge the limitation and recommend oil system modifications before track use.

Where to look: FA20D engine connecting rod bearings, crankshaft journal area

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The FA20D flat-four boxer uses a shallow wet sump with a single centrally located oil pickup tube and inadequate factory baffling. Under sustained lateral cornering loads on circuit — particularly hard corner entry combined with trail braking — oil migrates toward the outside of the sump, uncovering the pickup. The resulting momentary oil pressure drop at high RPM collapses the hydrodynamic wedge on big-end rod bearing journals, most critically journals #2 and #3 which sit furthest from the crankshaft gallery entry point. With a 7400rpm redline, journal damage accumulates within seconds of film loss, resulting in spun bearings. This is the same wet-sump oil-surge mechanism that plagued predecessor Subaru EJ engines. Factory sump baffling is designed for road use only and is wholly inadequate for sustained circuit cornering at greater than 0.8g.

Where to look: Engine lower block — crankshaft big-end rod bearing journals #2 and #3, FA20D wet sump oil pickup

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Cars in the first production run (roughly April 2012 to May 2013 build dates) were fitted with valve springs that can fracture, which can stall the engine while driving and, if a spring lets go, cause serious internal engine damage. Toyota/Subaru issued a worldwide recall and the fix (new springs) is done free of charge. The danger with a used one is buying a car where the recall was never completed. Once fixed, this is a non-issue.

Where to look: Boxer engine, cylinder heads (valve springs inside the heads)

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The early FA20D sump design places the oil pickup in a position susceptible to oil surge under sustained lateral acceleration, such as on a circuit or aggressive road driving. Oil migrates away from the pickup under cornering loads, causing momentary or sustained oil pressure loss. Toyota and Subaru acknowledged the issue and made an oil baffle plate upgrade available through dealer service bulletins; aftermarket baffles and accusumps became widely adopted by track users.

Where to look: FA20D oil sump and oil pickup tube – horizontal boxer engine layout below the crankshaft centreline

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Under sustained high-RPM use such as track driving, FA20 piston ring lands fatigue and break, causing catastrophic engine failure.

Where to look: See description

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The FA20D's well-documented piston ring oil consumption causes unburned or partially burned oil to enter the exhaust stream, contaminating and thermally damaging the catalytic converter's precious metal substrate. Over time the catalyst matrix becomes fouled and eventually fractures, causing exhaust restriction and triggering oxygen sensor fault codes. The fault is a direct downstream consequence of the piston ring issue and is disproportionately common on vehicles where oil consumption was left unmanaged.

Where to look: Catalytic converter located in the exhaust downpipe beneath the engine bay, between the engine and the main muffler

Parts involved: Catalytic converter.

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ZN6 86 GT and GTS models were optionally fitted with a Torsen Type-1 helical LSD; many owners upgrade to or install a clutch-type plate differential (OS Giken, Cusco, Kaaz) for performance driving. Clutch-type plate differentials on this platform are sensitive to heat cycling and lubricant degradation. Repeated aggressive corner exits, wet-road launches, and autocross use without correct LSD oil maintenance cause progressive friction material loss from the clutch pack. Worn packs lose locking capacity asymmetrically — first becoming inconsistent under partial throttle before eventually behaving as an open differential. Even factory Torsen units develop clunking from worn thrust surfaces after sustained motorsport use. The correct service is GL-5 fluid with friction modifier at 20,000–25,000km intervals; owners using standard gear oil without modifier accelerate pack wear significantly.

Where to look: Rear differential housing — LSD clutch pack and spider gear assembly

Parts involved: Clutch.

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The 86 manual transmission 4th and 5th gear synchromesh rings wear on track-driven examples from sustained high-rpm engagement. Worn synchros cause baulking and grinding when changing into the affected gear under normal road conditions.

Where to look: Manual transmission 4th and 5th gear synchromesh rings

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The 2018-2019 Toyota 86 (which uses the Subaru FA20 boxer engine) has a Denso fuel pump whose plastic impeller can crack, swell and jam, cutting fuel supply. The result is the engine stalling without warning while driving, or a no-start. It was part of the very large global Denso pump recall (the 86/BRZ were covered by Subaru campaign 21V-587) and the replacement pump is fitted free of charge. Buying one where the recall has not been done leaves you with a genuine stall risk.

Where to look: Fuel pump inside the fuel tank (under the car / under rear seat access)

Parts involved: Water pump.

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The clutch master cylinder on manual 86 models develops internal seal deterioration causing hydraulic fluid bypass within the cylinder bore. The result is a clutch pedal that gradually loses pressure, sinks toward the floor under sustained pressure, or requires repeated pumping to restore clutch disengagement. In acute failure the pedal drops to the floor mid-drive, leaving the driver unable to select gears. This is a documented wear pattern across multiple ZN6 production years and is distinct from normal clutch plate wear.

Where to look: Clutch master cylinder mounted on the engine-side firewall, driver's side, connected to the clutch pedal pushrod

Parts involved: Clutch.

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The 6-speed manual is known for a notchy, sometimes crunchy shift, most often felt going into 5th and 6th (and worse when cold). On many cars it is just the gearbox's character and improves with a fresh gearbox oil change, but on hard-driven or high-km cars the synchros can genuinely wear and grind, which is an expensive gearbox job. Test it thoroughly before buying.

Where to look: Manual gearbox / gear lever

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The FA20 uses both port and direct injection (D-4ST system). On short-trip urban examples, port injection wash may be insufficient to prevent carbon accumulation on intake valve faces from crankcase blow-by vapours. Heavy carbon deposits cause rough idle and hesitation at partial throttle.

Where to look: Intake valves in both cylinder heads accessible from intake manifold side

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The ZN6 Toyota 86/Subaru BRZ FA20 2.0 flat-four hydraulic valve lifters tick audibly on cold start from oil drainback when the engine sits for more than a few hours. The tick is caused by oil draining from the lifter bodies during shutdown, requiring several seconds of oil pressure to refill them. Persistent ticking beyond 30 seconds at operating temperature indicates worn lifters or an oil pressure issue.

Where to look: FA20 hydraulic valve lifters in both cylinder heads

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The ZN6 86 uses a two-piece propeller shaft with a centre support intermediate bearing mounted to a pressed-steel crossmember bracket beneath the cabin floor. The rubber isolation bonding ring that decouples the bearing housing from the crossmember is prone to early hardening and delamination caused by heat, ozone, and age. Once the rubber isolation loses compliance, rotational vibration from the propeller shaft transfers directly into the body structure at frequencies that resonate with the floor pan at approximately 30–50 km/h. Above 70 km/h the resonance frequency falls outside the excitation range and the drone disappears. This speed-band-specific nature frequently leads to misdiagnosis as a tyre or wheel-balance issue. In progressive failure the bearing race itself degrades with increasing roughness, and if neglected will fail catastrophically requiring an emergency tow. The vibration is equally present under power, overrun, and neutral coasting — distinguishing it from drivetrain-load-dependent faults.

Where to look: Two-piece propeller shaft — intermediate carrier bearing, rubber isolation bonding ring, crossmember bracket mount

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The ZN6 86 rear wheel bearings are pressed-in double-row angular contact units integrated into the rear knuckle carrier. Under the lateral cornering loads generated by a lightweight rear-wheel-drive sports car — especially with performance or semi-slick tyres — the factory bearings experience accelerated inner race fatigue compared to a conventional passenger car of similar weight. The bearing contact zone is optimised for standard road use and is not rated for sustained track cornering at elevated lateral G. Failure begins as a cyclic drone that increases with vehicle speed and changes character under lateral weight transfer, progressing to roughness and ultimately to hub wobble with tyre-to-guard contact in extreme cases. The integrated ABS tone ring on the outer bearing race means a damaged bearing can also trigger spurious ABS activation before audible symptoms become pronounced.

Where to look: Rear knuckle carrier — double-row angular contact wheel bearing and hub assembly with integrated ABS tone ring

Parts involved: Wheel bearing.

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Front lower arm ball joints wear causing clunking and handling imprecision on the lightweight 86.

Example of the part — not this vehicle

Where to look: Front lower suspension control arms

Parts involved: Ball joint.

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Front and rear brake caliper guide pins seize from corrosion causing uneven pad wear.

Where to look: Front and rear brake calipers

Parts involved: Brake disc and pads.

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Rear multi-link suspension arm bushes harden and collapse causing rear knocking and handling imprecision.

Where to look: Rear multi-link suspension arm bushes

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The front anti-roll bar end links on the ZN6 86 use ball-joint connections that wear over time, particularly on vehicles driven on rough NZ or AU roads or used at the track where suspension loading is repeated aggressively. As the ball joint develops play within its housing, a distinct knocking or clunking sound is produced over sharp bumps, speed bumps, or during abrupt cornering load transitions. The fault is common across the ZN6 fleet by the time cars reach 50,000 to 80,000 km and is regularly cited as a reason for WOF failure. Replacement is straightforward and inexpensive but the fault is often deferred by owners, causing it to appear frequently at the point of sale.

Where to look: Front suspension, anti-roll bar end links connecting the bar to the lower strut body on each side

Parts involved: Ball joint.

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FA20 rear main oil seal weeps oil onto the bellhousing and clutch, causing clutch slip and contamination on manual transmission examples.

Where to look: FA20 rear main oil seal behind the flywheel

Parts involved: Clutch.