Question 1

Sequential Twin-Turbo System Failures

Accepted Answer

A flat spot or hesitation in the 3,500-4,500 RPM range during full-throttle acceleration. Boost may spike or surge unpredictably. The car feels fast below 3,500 RPM and above 5,000 RPM but stumbles in the transition zone. The sequential twin-turbo system uses a primary turbo at low RPM and transitions to both turbos above ~4,000 RPM. This transition is managed by a complex system of vacuum-actuated valves, solenoids, and an exhaust gas control valve (EGCV). After 25+ years, these components fail: - EGCV (Exhaust Gas Control Valve): Sticks open or closed, preventing proper exhaust routing between the turbos. - Vacuum solenoids: Six solenoids control the transition sequence. Any failure disrupts the transition. - Vacuum lines: The rubber vacuum lines crack and develop leaks, causing erratic valve operation. - Pre-turbo exhaust bypass valve: Sticks, preventing the secondary turbo from receiving exhaust gas. Diagnosis requires methodical testing of each component in the sequential system. Replace all vacuum lines with silicone hose as a first step ($50, one afternoon). Test each solenoid individually. The EGCV can be cleaned or replaced ($200-400). For a comprehensive fix, rebuild the entire sequential system with new solenoids, actuators, and gaskets ($1,000-2,500). Alternatively, delete the sequential system entirely and run a single larger turbo. This is a common modification that simplifies the system dramatically. A quality single-turbo conversion using a BorgWarner or Garrett turbo with a proper manifold and tune runs $3,000-8,000 depending on the turbo size and supporting modifications.

Question 2

Turbo Seal Wear (High Mileage)

Accepted Answer

Blue smoke on cold startup (oil pooled in the turbo housing overnight drains into the exhaust when started). Blue smoke on deceleration (intake manifold vacuum pulls oil past the compressor seals). Oil residue in the intercooler piping. Increased oil consumption without external leaks. The CT-20 turbochargers use oil-fed journal bearings with carbon face seals. After 150,000+ km, the seals wear and allow oil to migrate past the turbo shaft into either the exhaust (turbine side) or the intake (compressor side). Heat cycling accelerates seal degradation. Rebuild both turbochargers. A turbo specialist can reball and reseal the CT-20s for $600-1,200 (both turbos). This is worthwhile if you're keeping the sequential system. If you're planning a single-turbo conversion, simply do the conversion and discard the worn CT-20s. While the turbos are out, replace the oil feed and drain lines. Restricted oil drain lines (from carbon buildup) are a common secondary cause of turbo seal failure, the oil can't drain fast enough and builds pressure behind the seals.

Question 3

Timing Belt Failure

Accepted Answer

Catastrophic engine damage. The 2JZ is an interference engine, if the timing belt breaks, the pistons strike the open valves, bending them and potentially damaging the pistons, head, and block. The engine stops instantly and will not restart. The timing belt is a rubber component with a finite service life. Toyota specifies replacement every 100,000 km or 7 years. Many A80s have changed hands multiple times, and the timing belt service history may be incomplete or unknown. Replace the timing belt, water pump, belt tensioner, and both idler pulleys as a set. Do not replace just the belt, the tensioner and idler bearings have the same service life and a failed tensioner will throw the belt. Use genuine Toyota or Gates Racing parts. Cost: $800-1,500 including parts and labour. This is a moderately involved job (6-8 hours) that requires removing the front of the engine.

Question 4

Cam Cover Gasket Oil Leaks

Accepted Answer

Oil seeps from the edges of the cam covers (rocker covers), running down the sides of the engine. Oil smell from the engine bay. Oil drips onto the exhaust manifold (fire risk on the turbo side). The rubber cam cover gaskets harden and shrink over time, losing their seal. The half-moon seals at the rear of the cam covers are particularly prone to leaking. Replace the cam cover gaskets and half-moon seals. This is a straightforward job, remove the cam covers, clean the sealing surfaces, and install new gaskets. Use genuine Toyota gaskets. Cost: $100-200 for parts, 2-3 hours of work. Apply a small bead of RTV sealant at the corners where the cam cover meets the head, these are the most common leak points.

Question 5

Oil Cooler O-Ring Leak

Accepted Answer

Oil leak from the oil cooler housing on the front of the engine, typically dripping down onto the oil filter and undercarriage. The O-ring seal between the oil cooler and the engine block hardens with age and heat. Replace the O-ring. The oil cooler assembly unbolts from the front of the block. Cost: $20 for the O-ring, 1-2 hours of work. While it's apart, flush the oil cooler core, they can clog with sludge on neglected engines.

Question 6

VVTi Solenoid Issues (Later Models)

Accepted Answer

Rough idle, loss of mid-range torque, check engine light. Fault codes related to Variable Valve Timing. The later 2JZ-GE engines (1997+) feature Toyota's VVTi system. The VVTi oil control valve (solenoid) can clog with oil sludge, preventing proper cam timing adjustment. Remove and clean the VVTi solenoid with carburettor cleaner. If cleaning doesn't resolve the issue, replace the solenoid ($100-200). Regular oil changes with quality oil prevent this issue.

Question 7

V160 Getrag Synchro Wear

Accepted Answer

Crunching or grinding when shifting into 2nd or 3rd gear, particularly during quick downshifts when cold. The synchros may improve once the gearbox oil warms up. The V160 synchros wear over time, particularly in cars that have been driven hard or used for drifting. The V160 is a strong gearbox but the synchros are not indestructible. Using incorrect gearbox oil (too thin) accelerates wear. The V160 specifies 75W-90 GL-4, do not use GL-5, as the EP additives can damage the brass synchros. A synchro rebuild by a gearbox specialist runs $2,000-4,000. This is an expensive repair but far cheaper than replacing the entire gearbox ($5,000-10,000 secondhand). For a temporary measure, switching to Redline MT-90 or Motul Gear 300 (75W-90 GL-4) can improve shift quality by providing better synchro lubrication.

Question 8

Auto-to-Manual Conversion Issues

Accepted Answer

Various driveability problems on cars that have been converted from automatic to manual transmission, clutch engagement problems, speedometer not reading correctly, ABS faults, reverse light not working, ECU issues. The auto-to-manual conversion requires changes beyond just the gearbox. The pedal box, master cylinder, clutch hydraulic line, driveshaft, ECU (auto and manual ECUs have different programming), instrument cluster (speedometer signal differs), and reverse light switch all need to be addressed. Many conversions are incomplete, the converter does the mechanical work but skips the electrical integration. Systematically address each system: - ECU: Needs to be a manual-spec ECU, or the auto ECU needs the transmission programming modified. - Speedometer: The auto uses a VSS from the transmission; the manual uses a different signal. The instrument cluster may need a speed signal converter. - ABS: The ABS system reads wheel speed differently with the manual trans. If the ABS light is on after a conversion, the speed signals aren't integrated correctly. - Reverse lights: Wire the reverse light switch from the manual gearbox to the existing reverse light circuit. A thorough conversion that addresses all these points costs $5,000-10,000 total. A dodgy conversion that only does the mechanical swap costs less but leaves you with a car that has multiple electrical issues.

Question 9

Radiator Degradation

Accepted Answer

Engine temperature creeps up in traffic or on hot days. Coolant loss. Green or pink coolant stains on the front of the engine or on the ground beneath the car. The factory radiator is an aluminium-core, plastic-tank design. The plastic tanks become brittle with age and develop cracks at the crimped seams where they join the core. The core itself can clog internally from sediment in old coolant. Replace with a full-aluminium aftermarket radiator ($300-600). This is one of the best value upgrades on any A80, the all-aluminium unit provides better cooling, eliminates the plastic tank failure point, and lasts indefinitely. While replacing the radiator, flush the entire cooling system, replace the thermostat ($30-50), and install new upper and lower hoses.

Question 10

Heater Core Leak

Accepted Answer

Sweet coolant smell inside the cabin. Fogging on the windscreen (coolant mist from the heater core mixing with cabin air). Coolant loss with no visible external leak. Wet carpets on the passenger side. The heater core is a small radiator inside the dashboard that provides cabin heating. After decades, the thin tubes corrode and develop pinhole leaks. Contaminated or never-changed coolant accelerates corrosion. Replace the heater core. On the A80, this requires significant dashboard disassembly, budget 6-10 hours of labour. The heater core itself is $100-200, but the labour makes this a $500-1,500 repair at a workshop. Some owners bypass the heater core (loop the hoses) as a temporary fix, but this means no cabin heating.

Question 11

Interior Trim Deterioration

Accepted Answer

The soft-touch coating on interior trim pieces becomes sticky, gummy, and eventually peels off in black flakes. Affects the centre console, door handle surrounds, and other trim pieces with the soft-touch finish. Toyota used a rubberised soft-touch coating on interior plastics across many models in this era. The coating breaks down from UV exposure, heat, and the oils from hands. It's a known Toyota deficiency that affects models from the 1990s and 2000s. Strip the coating with isopropyl alcohol or a dedicated plastic coating remover. Sand the underlying plastic smooth, then either repaint with a textured trim paint or wrap in vinyl/leather. Alternatively, source replacement trim pieces from a wrecker, but they'll likely have the same problem. Some owners send the trim pieces to a specialist for professional re-coating ($100-300 per piece).

Question 12

Dashboard Cracking

Accepted Answer

Cracks develop across the top surface of the dashboard, particularly near the windscreen and around the defroster vents. May start as a single crack and spread into a network of splits. UV exposure and heat cause the dashboard material to become brittle over time. Australian sun is particularly harsh on these dashboards. Cars that have been garaged fare much better. A replacement dashboard in good condition costs $1,000-2,000 from a wrecker (prices reflect the scarcity). Dashboard repair specialists can fill and re-skin cracked dashboards for $500-1,000. A dashboard cover or mat is the cheapest solution ($50-100) but changes the interior appearance.

Question 13

Targa Roof Seal Deterioration

Accepted Answer

Water leaks into the cabin during rain or car washing. Stained headliner, musty smell, wet carpets. Same as the A70, the rubber seals perish from age and UV exposure. The A80's targa panel is aluminium and lighter than the A70's, but the sealing principle is the same. Replace the targa roof seals. Toyota still supplies these. Clean and lubricate the seal channels. Apply anti-seize to the targa bolts on reassembly. Cost: $200-400 for seals and installation.

Question 14

Instrument Cluster Pixel Fade

Accepted Answer

The LCD displays in the instrument cluster (odometer, trip computer, clock) lose pixels, segments of the display stop working, making the readout unreadable. The LCD displays use ribbon connectors that develop poor contact over time from thermal cycling. The solder joints on the circuit board can also crack. The ribbon connector can be resoldered or replaced. Instrument cluster repair specialists can rebuild the display for $200-400. Some owners replace the entire cluster with a used unit from a wrecker ($300-600), but ensure the odometer reading is documented for compliance.

Question 15

Wiring Harness Issues on Modified Cars

Accepted Answer

Random electrical faults, misfires, no-start conditions, erratic gauge behaviour, blown fuses, intermittent boost control problems. Modified A80s often have wiring that's been spliced, extended, and re-routed by multiple owners. Each modification adds potential failure points. Poor soldering, scotch locks, exposed splices, and incorrect wire gauges are all common. For a car with extensive wiring issues, a complete engine harness replacement is often the most cost-effective solution. Aftermarket engine harnesses from Wiring Specialties and similar suppliers are available ($800-2,000). For targeted repairs, trace each fault systematically with a multimeter, repair with proper soldering and heat-shrink, and re-loom with split conduit.

Question 16

Power Antenna Motor Failure

Accepted Answer

The power antenna doesn't extend or retract, or extends/retracts partially. Grinding noise from the antenna motor. The antenna mast cable (a toothed nylon strip) breaks or jams inside the motor housing. The motor itself can also fail electrically. Replace the antenna mast and cable ($30-50 for the mast, 30 minutes to fit). If the motor has failed, replace the entire assembly ($100-200). Some owners delete the power antenna entirely and fit a stubby antenna or shark fin.

Question 17

Fuel Pump Degradation

Accepted Answer

Engine stumble or cut-out under high boost/high RPM. Lean condition visible on wideband O2 gauge at full throttle. The engine may run fine at partial throttle but starve for fuel under maximum demand. The stock fuel pump is adequate for factory power but marginal at higher boost levels. Even at stock power, a 25+ year old fuel pump has reduced output compared to new. Fuel delivery degrades gradually, so the problem develops slowly. For stock cars, a new OEM-spec fuel pump restores original fuel delivery ($150-300). For modified cars, an upgraded fuel pump is essential. Common choices: Walbro 255lph ($100-150) for builds up to ~450 hp, Walbro 450lph or AEM 340lph for builds up to ~650 hp, and dual fuel pump setups for big-power builds. Any fuel pump change should be followed by a fuel pressure check at the rail under full load.

Supra (A80)

Supra (A80) known problems