L20A

Nissan L20A engine: Experiences, issues, fuel consumption and used-car buying tips

• Legendary durability: Old-school inline six-cylinder petrol engine known for its smooth operation and indestructible block.
• Maintenance: Timing is chain-driven, which reduces costs, and mechanical parts are not expensive (Depends on the market).
• Fuel supply: Uses a carburetor, which today requires specific specialist knowledge for proper adjustment.
• Fuel consumption: Very high in city driving; the engine is quite thirsty compared to modern units.
• Performance: With only 97 hp, the engine is rather “lazy” in heavier bodies such as the Nissan Laurel.
• LPG: Handles installation of a classic venturi LPG system very well.
• Buying used: The biggest problem today is finding specific carburetor parts and body panels for the car it’s installed in.

Contents

• Introduction: Get to know an old-school classic
• Technical specifications
• Reliability and maintenance
• Specific parts and costs
• Fuel consumption and performance
• Additional options and modifications
• Gearbox and drivetrain
• Buying used and conclusion

Introduction: Get to know an old-school classic

When talking about engines that marked the Japanese automotive industry of the seventies and early eighties, Nissan’s L-series is unavoidable. The L20A engine is an inline six-cylinder that was installed in cult models such as the Nissan Laurel (HLC230), Skyline and Fairlady. It is known primarily for its silky-smooth operation and overengineered construction, which gives it incredible longevity. Although its 97 hp won’t break any records, this unit set durability standards in its time and today represents a real treat for classic car enthusiasts.

Technical specifications

Reliability and maintenance

Does this engine have a timing belt or chain?

The Nissan L20A uses a timing chain (double-row chain) to drive the camshaft. This was one of the best technical solutions of that era, ensuring high reliability and freeing drivers from the frequent timing failures typical of belt-driven engines.

At what mileage is a major service required?

Since the engine has a chain, a classic “major service” is not done at 60,000 or 80,000 km intervals. Replacement of the chain, sprockets and guides is recommended only when the chain becomes audible (rattling at cold start), which in practice usually happens between 200,000 and 300,000 km. Regular maintenance comes down to minor servicing – oil and filter changes and occasional valve clearance adjustment, since this engine does not have hydraulic lifters.

What are the most common failures on this engine?

The block and crankshaft themselves are virtually indestructible, but due to the engine’s age, the surrounding peripherals cause headaches. The most common issues include a misadjusted carburetor, which makes the engine run unevenly, misfire or stall. Symptoms also include black smoke from the exhaust due to an overly rich mixture. Problems with the distributor are also frequent (on older versions, the contact points lose their gap) as well as arcing and failure of the spark plug wires. On high-mileage examples, valve stem seals tend to harden and fail, so the engine starts to burn blue oil smoke on cold start.

How many liters of oil does this engine take and which grade is recommended?

The engine holds approximately 4.5 to 5 liters of oil including the filter. Given the clearances in these older engine designs, fully synthetic oils are too thin. A quality mineral or semi-synthetic oil of 15W-40 or 10W-40 grade is recommended.

Does it consume oil between services?

Yes, for engines of this generation it is completely normal to consume a certain amount of oil. Consumption of 0.3 to 0.6 liters per 1,000 km is considered acceptable, depending on the condition of the piston rings and valve stem seals. If consumption exceeds 1 liter, it is time for more serious work on the cylinder head or a partial overhaul.

Spark plugs and ignition

Since this is a petrol engine, spark plugs need to be replaced every 20,000 to 30,000 km. Standard copper spark plugs are used and they are quite inexpensive (Depends on the market). If the engine uses contact points (condenser and points in the distributor), their gap should be checked and adjusted (or replaced) with every spark plug change to keep ignition timing precise.

Specific parts and costs

Does the engine have a dual-mass flywheel?

No. This model uses a classic solid flywheel. Dual-mass flywheel technology was not used on petrol engines of this type at the time. This significantly reduces drivetrain maintenance costs.

Fuel system

The L20A engine does not use modern injectors; instead, fuel supply is handled by a carburetor. The problem lies in the fact that, due to age and fuel contamination, the jets and internal passages in the carburetor clog, and the diaphragms crack. The cost of refurbishment is not particularly high in terms of parts, but finding a mechanic who knows how to properly tune a multi-barrel carburetor has become a real challenge (Depends on the market).

Turbocharger, DPF, EGR and AdBlue

This is a naturally aspirated engine without a turbocharger. Also, as an old petrol engine, it does not have a DPF filter, does not have a modern EGR valve, and does not use AdBlue fluid. The absence of these emissions systems makes it extremely simple and cheap to maintain at a basic level, without the risk of the expensive failures that plague modern cars.

Fuel consumption and performance

What is the real fuel consumption in city driving?

There should be no illusions – this engine is extremely thirsty. In city driving, the heavy body of the Nissan Laurel and the old carbureted fuel system result in real-world consumption of between 12 and 15 liters per 100 km. In winter, with a heavier right foot, that figure can be even higher.

Is this engine “lazy”?

Absolutely. With its 97 hp (71 kW) spread across six cylinders, the focus is on smoothness rather than performance. In a heavy saloon like the Laurel, throttle response is sluggish and acceleration is slow by today’s standards. The engine needs higher revs to extract the most from its modest torque, but it will never pin you to the seat.

Behavior on the highway

On the highway, the engine is extremely quiet and smooth in terms of vibration, thanks to its inline six-cylinder layout. However, due to old gearboxes with short ratios (often 4-speed), at a cruising speed of 130 km/h the engine spins at a relatively high 3,800 to 4,200 rpm (Depends on the gearbox fitted). This significantly increases cabin noise and fuel consumption, so a more pleasant cruise is achieved at around 100–110 km/h.

Additional options and modifications

LPG installation

This is an ideal engine for LPG conversion. Thanks to its simple mechanics and intake manifold, a basic venturi (vacuum) LPG system works perfectly. If installed correctly, there is no risk of backfire. Running on LPG drastically reduces the operating costs of this “thirsty” engine, and the performance loss of about 5–10% is barely noticeable given its already existing “laziness”.

Possibility of “chipping” (Stage 1)

Not possible. The engine does not have an electronic control unit (ECU) managing fuel injection. Everything is completely mechanical. Any power increase has to be done the old-school tuning way: machining the cylinder head, installing a more aggressive camshaft, a freer-flowing exhaust, or fitting twin/triple (e.g. Weber) carburetors. Such modifications are expensive and exceed the usual practical value of the car (Depends on the market).

Gearbox and drivetrain

Types of gearboxes

With the L20A engine, 4- or 5-speed manual gearboxes were fitted, as well as 3-speed automatic gearboxes. The manual gearboxes are extremely robust and durable.

Gearbox failures

On manual gearboxes, after several decades of use, the synchronizers are usually the first to fail, which manifests as grinding when shifting into second or third gear, or difficulty engaging first gear while the vehicle is stationary. As for the 3-speed automatics (often made by Jatco), they are virtually indestructible as long as they have oil, but they suffer from slow shifting and oil leaks at seals and gaskets due to material aging. The vacuum hoses that control the operation of the old automatic can crack, causing the gearbox to “refuse” to shift into a higher gear.

Clutch replacement

Since the model has a solid flywheel, the cost of replacing the clutch kit (pressure plate, disc, release bearing) is not high compared to modern vehicles (Depends on the market). The only issue can be sourcing and ordering the correct kit due to the rarity of the car.

Gearbox maintenance

For the manual gearbox, it is recommended to change the transmission oil (usually 75W-90 or 80W-90 API GL-4) every 60,000 to 80,000 km. For automatics, the oil (ATF Dexron specification) and filter should be changed every 40,000 to 50,000 km to preserve the internal clutch packs.

Buying used and conclusion

What must be checked before buying?

Buying a car with an L20A engine today is not buying a means of transport, but a classic car (oldtimer). When inspecting, focus on the following:

• Timing chain rattle: Ask the seller to keep the engine completely cold. Listen to the front of the engine during the first few seconds after starting. Metallic rattling indicates a stretched chain and worn guides.
• Idle quality: A 6-cylinder engine should run “like a clock”, almost inaudibly and without vibrations in the cabin. If it shakes or surges, the carburetor or ignition system needs an overhaul.
• Exhaust smoke: Blue smoke when revving the engine after a short idle period is a sign of worn valve stem seals or piston rings.
• Cooling system: Check the coolant. These engines were often run on plain water, which causes corrosion in the water passages and overheating issues (blown head gasket).

Who is this engine for?

The Nissan L20A engine is definitely not intended for drivers looking for an economical, everyday city car. Due to its high fuel consumption, sluggish performance and the lack of mechanics familiar with old systems, it is strictly for enthusiasts. It is aimed at collectors and lovers of JDM classics who appreciate the unmatched sound and silky operation of an inline six, and who don’t mind spending weekends adjusting points and the carburetor in the garage.