Porsche 968, Known Issues and Common Problems
Overview
The Porsche 968 is a well-engineered, robustly built sports car. It was the culmination of nearly two decades of development of the transaxle platform, and by 1992 Porsche had resolved most of the issues that plagued the earlier 924 and early 944 models. The 968 benefits from lessons learned across thousands of 944s, and it shows.
That said, these are now 30+ year old cars, and even the best engineering cannot prevent age-related deterioration. The 968 has a handful of well-known weak points, several of which are inherited from the 944 platform and one, the VarioCam system, that is unique to the 968. Understanding these issues before you buy, and maintaining them properly after, is the difference between a rewarding ownership experience and an expensive headache.
The golden rule with the 968 is the same as with the 944: the timing belt must be replaced on schedule, without exception. Everything else is manageable. A broken timing belt is terminal.
1. Timing Belt Failure
Severity: Critical
What happens: The timing belt breaks, the pistons collide with the valves, and the engine is destroyed. Bent valves, damaged pistons, scored cylinder bores, and often cracked cylinder head. The engine is scrap.
Why it happens: The 3.0-litre M44/43-44 engine is an interference design, meaning the pistons and valves occupy the same space at different times. The toothed rubber timing belt keeps them synchronised. The belt degrades with age and use, rubber hardens, teeth crack, and the belt eventually fails. Heat cycling, oil contamination from leaking seals, and incorrect tension all accelerate failure.
Symptoms: None. The belt fails without warning. By the time you hear anything, it’s already too late.
Fix cost: The fix is prevention. A timing belt replacement (belt, tensioner, idler rollers, water pump, and balance shaft belt) costs $2,000-3,500 at a specialist. An engine rebuild after belt failure costs $10,000-20,000, if the block survives at all.
The rule: Replace every 5 years or 60,000 km, whichever comes first. No exceptions, no extensions, no “it looks fine.” If you don’t know when the belt was last changed, change it immediately.
2. VarioCam Tensioner Failure
Severity: Serious
What happens: The hydraulic chain tensioner that controls the timing chain between the exhaust camshaft and the intake camshaft loses tension. The chain becomes slack, causing the intake cam timing to become erratic. In severe cases, the chain can jump a tooth, significantly altering cam timing and causing the engine to run poorly or not at all.
Why it happens: The VarioCam system is unique to the 968 (within the transaxle family). It uses a hydraulic tensioner fed by engine oil pressure to maintain correct tension on the short timing chain that connects the two camshafts. The tensioner’s internal check valve can fail, allowing oil to drain back from the tensioner when the engine is off. On restart, the tensioner takes a moment to re-pressurise, and during that window the chain is slack.
Symptoms: A metallic rattling or chattering noise from the top of the engine on cold start, typically lasting 2-10 seconds before oil pressure builds and the tensioner takes up the slack. The noise is most noticeable on the first start of the day. As the problem worsens, the rattle persists longer and may be accompanied by rough idle, reduced low-rpm torque, and occasionally a check engine light.
Fix cost: $1,500-3,000 including parts and labour. The repair involves removing the cam cover, replacing the chain tensioner (and usually the chain itself while access is available), and resetting the cam timing.
3. Balance Shaft Belt Failure
Severity: Serious
What happens: The toothed belt that drives the twin balance shafts breaks. The balance shafts seize or spin out of phase, causing severe engine vibration. In the worst case, a seized balance shaft can crack the engine block.
Why it happens: The balance shaft belt is a separate toothed rubber belt that runs off the crankshaft. It degrades at the same rate as the timing belt but is sometimes overlooked during servicing. Some workshops replace the timing belt but skip the balance shaft belt to save cost, this is false economy.
Symptoms: If the belt breaks while the engine is running, you’ll feel immediate and severe vibration. The engine will sound rough and out of balance. If caught immediately (by stopping the engine), the damage may be limited to a replacement belt. If the engine continues to run with a broken belt, internal damage is likely.
Fix cost: $300-600 for the belt alone (usually done during timing belt service for minimal additional cost). If the balance shaft seizes and damages the block, repair can exceed $5,000.
4. Dashboard Cracking
Severity: Cosmetic (but expensive)
What happens: The dashboard surface develops cracks, typically starting around the windscreen defroster vents and spreading across the top surface. In severe cases, the entire dashboard surface crazes into a network of deep cracks.
Why it happens: The dashboard is made of a vinyl-covered foam composite that degrades under UV exposure and heat. Australian cars are particularly susceptible due to high UV levels. The foam substrate shrinks as it dries out, the vinyl surface cannot accommodate the movement, and it cracks. Cars that have spent their lives garaged fare better, but even garaged cars will eventually crack.
Symptoms: Visible cracks on the dashboard surface, usually starting as fine lines and progressing to deep fissures.
Fix cost: A professional dashboard restoration (removing, re-skinning, and refitting) costs $2,000-4,000. A replacement dashboard from Porsche (if available) is $3,000-5,000+. Dashboard caps or covers are available for $200-500 and cover the problem cosmetically but do not fix it.
5. Clutch Replacement Expense
Severity: Moderate (but financially significant)
What happens: The clutch wears out, as all clutches eventually do. The issue with the 968 is not that the clutch fails prematurely, it’s that replacing it is extraordinarily labour-intensive.
Why it happens: The 968’s transaxle layout means the gearbox is at the rear of the car, connected to the engine by the torque tube. To replace the clutch, the torque tube must be separated from the engine and the gearbox. This is a full-day job for an experienced technician. The clutch itself is a standard wear item, but the labour to access it is 5-8 hours.
Symptoms: Clutch slip under hard acceleration (especially in higher gears), juddering on take-off, difficulty engaging gears, and a high biting point.
Fix cost: $2,500-4,000 for a complete clutch kit (pressure plate, disc, release bearing, pilot bearing) plus labour. Given the labour involved in accessing the clutch, it makes sense to replace the rear main seal, torque tube bearing, and any other items that are accessible only with the torque tube removed.
6. DME Relay Failure
Severity: Moderate
What happens: The engine cranks but will not start. No fuel delivery, no spark. The car is completely dead from an ignition perspective.
Why it happens: The DME (Digital Motor Electronics) relay is a standard Bosch relay that controls power to the fuel pump, the engine management ECU, and the fuel injectors. The relay’s internal solder joints crack from thermal cycling, and the contacts corrode. This is the same relay and the same failure mode as the 944.
Symptoms: Intermittent no-start conditions that may resolve if you tap the relay or wait and try again. Eventually, the relay fails permanently and the car will not start at all. No fuel pump prime (the brief whirring sound from the rear of the car when you turn the ignition on) is a strong indicator.
Fix cost: $40-60 for a new relay. Five minutes to install. The relay is in the fuse box area on the driver’s side. Every 968 owner should carry a spare relay in the glovebox.
7. Oil Leaks
Severity: Moderate
What happens: Oil weeps or drips from various gasket surfaces on the engine. The most common leak points are the cam cover gaskets, the balance shaft cover gasket, the oil cooler seals, and the rear main seal.
Why it happens: Gaskets and seals degrade with age and heat cycling. The 3.0-litre engine runs warm, and 30+ years of thermal cycling hardens rubber and compresses gaskets. The cam covers are aluminium and can develop slight warping over time, compromising the gasket seal.
Symptoms: Visible oil on the engine exterior. The cam cover leak shows as oil running down the sides of the cylinder head. The balance shaft cover leak shows as oil at the front of the engine below the timing belt cover. The rear main seal weeps oil onto the torque tube bellhousing.
Fix cost: Cam cover gaskets: $200-400 (straightforward job). Balance shaft cover gasket: $300-600 (often done during timing belt service). Rear main seal: $2,000-4,000 (requires torque tube removal).
8. Cooling System Degradation
Severity: Moderate to Serious
What happens: Coolant leaks from the thermostat housing, radiator, or coolant hoses. In the worst case, overheating damages the cylinder head.
Why it happens: The thermostat housing on the 968 is a plastic component that becomes brittle with age and heat cycling. It cracks, leaking coolant. The radiator core degrades from the inside out, and aluminium radiators develop pinhole leaks at solder joints. Rubber coolant hoses harden and crack.
Symptoms: Coolant loss (check the coolant level regularly), visible coolant on the ground under the car, a sweet smell in the cabin from the heater core, or an overheating gauge reading. A cracked thermostat housing may leak slowly when the engine is cold and more aggressively when hot and pressurised.
Fix cost: Thermostat housing replacement: $300-600. Radiator replacement: $600-1,200 (aftermarket) or $1,500-2,500 (OEM). Full cooling system refresh (thermostat, housing, hoses, radiator, water pump): $2,000-4,000.
9. Power Window Regulators
Severity: Minor
What happens: The electric windows become slow, noisy, or stop working entirely. One window typically fails before the other.
Why it happens: The power window regulator mechanism uses plastic guides and a cable system that wear with age. The plastic guides crack, the cables fray, and the electric motor eventually burns out from working against increased friction.
Symptoms: Slow window operation, grinding or clicking noises during window movement, the window moving in jerks rather than smoothly, or complete window failure (usually in the down position, which is particularly inconvenient in the rain).
Fix cost: $300-600 per window for a regulator replacement, including parts and labour. Replacement regulators are available from Porsche and aftermarket suppliers.
10. Gearbox Synchro Wear (2nd Gear)
Severity: Moderate
What happens: Second gear crunches or grinds on downshifts, particularly when the gearbox is cold. Eventually, it grinds on upshifts as well.
Why it happens: Second gear synchromesh takes the most abuse in normal driving. Every downshift from third and every aggressive upshift from first loads the brass synchro ring. The 6-speed Getrag G44 gearbox used in the 968 is robust, but 30+ years of use wears the synchro material. Aggressive driving, missed shifts, and infrequent gearbox oil changes accelerate wear.
Symptoms: A brief crunch or grind when shifting into second, most noticeable when the gearbox is cold. As wear progresses, the crunch becomes more persistent and eventually occurs even with the gearbox at operating temperature. You may find yourself unconsciously double-clutching into second to avoid the crunch.
Fix cost: A gearbox rebuild with new synchro rings costs $3,000-5,000. The gearbox must be removed from the car (rear of the car, the transaxle comes out after disconnecting the torque tube). Some workshops can rebuild the gearbox in-situ, but most prefer to remove it.
11. Torque Tube Bearing Wear
Severity: Moderate
What happens: A vibration or drone develops at highway speeds, typically between 80-120 km/h. The vibration may change character with engine load (present on the overrun, absent under power, or vice versa).
Why it happens: The torque tube contains the driveshaft, which is supported by a centre bearing. This bearing wears with age and mileage, developing play that allows the driveshaft to vibrate. The bearing is a sealed unit that cannot be lubricated in service.
Symptoms: A vibration felt through the floor of the car, most noticeable at 90-110 km/h. The vibration is often described as a “droning” or “humming” that changes with speed rather than engine rpm. It can be confused with tyre vibration or wheel balance issues, but it persists regardless of tyre condition.
Fix cost: $1,500-3,000 for a centre bearing replacement. The torque tube must be removed, which involves separating it from both the engine and the gearbox. Given this labour, it is sensible to replace the clutch, rear main seal, and any other items accessible only with the torque tube removed.
12. ABS Sensor and Module Failures
Severity: Moderate
What happens: The ABS warning light illuminates on the dashboard and the ABS system is disabled. The brakes continue to function normally (without ABS intervention), but the car has no anti-lock capability.
Why it happens: The ABS wheel speed sensors corrode at the sensor tips (the gap between the sensor and the reluctor ring fills with debris or the sensor itself corrodes). The ABS control module, located in the engine bay, can fail due to internal solder joint cracking or capacitor degradation. Corroded wiring connectors at the wheel sensors are also a common cause.
Symptoms: ABS warning light on the dashboard. In some cases, the light illuminates intermittently (particularly over bumps, which momentarily disrupts the sensor signal). A diagnostic scan will show fault codes indicating which sensor or circuit has failed.
Fix cost: ABS wheel speed sensor replacement: $150-300 per sensor (parts and labour). ABS module repair (specialist electronic repair): $500-1,200. ABS module replacement (used, as new modules are discontinued): $800-2,000.
Preventive Maintenance Summary
- Timing belt, balance shaft belt, tensioner, rollers, and water pump every 5 years or 60,000 km. This is the single most important service item.
- VarioCam chain tensioner inspection at every timing belt service. Replace if any cold-start rattle is noted.
- Engine oil and filter every 10,000 km or annually. Use 10W-40 or 15W-40 semi-synthetic oil meeting Porsche specifications. 98 RON fuel only.
- Gearbox and differential oil every 60,000 km.
- Cooling system inspection annually. Replace thermostat housing and hoses at the first sign of cracking. Replace coolant every 3 years.
- Brake fluid every 2 years.
- DME relay replace preventively every 10 years, or carry a spare.
- Inspect for oil leaks at every service. Address cam cover and balance shaft cover leaks promptly before oil contaminates the timing belt.
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