C35A2 Engine

Honda C35A2 3.5 V6: Experiences, problems, fuel consumption and buying used

Key points (TL;DR)

• Exceptional refinement: This is an engine built for comfortable cruising, it runs extremely smoothly and quietly.
• Reliability: With regular maintenance, this engine is almost indestructible (“bulletproof”).
• Fuel consumption: Be prepared for high fuel consumption, especially in city driving (often over 15 l/100 km).
• Maintenance: Requires quality parts, and the major service is more expensive due to the V6 configuration.
• Gearbox: It almost exclusively comes with an automatic transmission which is reliable, but slow by today’s standards.
• LPG: It works very well on LPG, with mandatory valve clearance checks.

Contents

• Introduction and applications
• Technical specifications
• Reliability and maintenance
• Specific parts and costs
• Fuel consumption and performance
• Additional options and modifications (LPG & tuning)
• Transmission
• Buying used and conclusion

Introduction and applications

The C35A2 engine is the heart of Honda’s most luxurious sedan of the 1990s – the third-generation Honda Legend (KA9 chassis). It is an engine designed in an era when engineers had the final say, not accountants. This is a classic naturally aspirated V6 mounted longitudinally, intended to compete with German premium brands. Although the Honda Legend is front-wheel drive (which is unusual for this class and this engine layout), the C35A2 provides a driving feel very close to rear-wheel-drive cars thanks to its specific weight distribution.

This powerplant was not built for racing, but for devouring miles in absolute silence. It’s important to note that this is an evolution of the C-series engines (like in the first Honda NSX), but tuned for maximum comfort and torque at low rpm.

Technical specifications

Characteristic	Value
Displacement	3474 cc (3.5 L)
Configuration	V6, 90-degree angle
Power	151 kW (205 hp) at 5200 rpm
Torque	297 Nm at 2800 rpm
Engine code	C35A2
Injection type	Multipoint (indirect)
Induction	Naturally aspirated (no turbo)
Valves	24 valves (SOHC – single camshaft per head)

Reliability and maintenance

Timing belt or chain?

The Honda C35A2 uses a timing belt. This is a key maintenance item. Since this is a V6 engine, replacement is more complex and more expensive than on inline four-cylinders. If the belt snaps, the engine will suffer catastrophic damage (pistons hitting valves). It is recommended to replace it only as a complete kit together with tensioners, idler pulleys and the water pump.

Most common issues

This engine is considered extremely reliable, but age takes its toll:

• Valve cover gaskets and crankshaft seals: Oil leaks are the most common issue. Over time, the rubber hardens and the engine starts to “sweat”. This is not an expensive repair, but it is labor-intensive.
• EGR valve: It can get clogged with soot, which leads to rough running or the “Check Engine” light coming on. Cleaning usually solves the problem.
• Main fuel pump relay: A well-known Honda weak point from that era. If the car cranks but won’t start (especially when the cabin is hot), the problem is most likely cracked solder joints in the relay.
• Camshaft position sensor: It can fail, causing the engine to stall or preventing it from starting.

Service intervals and oil

The major service should be done every 100,000 km or every 6 to 7 years (whichever comes first). Do not risk running an old belt.

The engine takes approximately 4.6 liters of oil (with filter). Honda recommends 5W-30 or 10W-40 (semi-synthetic or synthetic) for this engine. Given the mileage these engines have nowadays, 10W-40 is often a better choice for older units.

Oil consumption: A healthy C35A2 should not consume significant amounts of oil. Consumption up to 0.5 liters per 10,000 km is acceptable. If it uses more, the usual culprits are valve stem seals (causing bluish smoke on cold start) or leaks from gaskets.

Spark plugs

The recommended replacement interval depends on the type of spark plug you use. If you use standard copper plugs, they should be replaced every 30–40,000 km. However, the recommendation for this engine is iridium spark plugs (NGK or Denso), which are replaced every 100,000 km. Since access to the rear bank of cylinders is a bit more difficult, iridium plugs save both time and the mechanic’s hands.

Specific parts and costs

Fuel injection system and injectors

The engine uses classic indirect fuel injection. The petrol injectors are extremely durable and rarely cause problems. They are not as sensitive to fuel quality as modern direct injectors. Ultrasonic cleaning at high mileage (over 300,000 km) can restore smooth running and slightly reduce fuel consumption.

Turbo, DPF, AdBlue, EGR

• Turbo: None. The engine is naturally aspirated, which means fewer potential failures (no turbocharger rebuilds).
• DPF / AdBlue: None. This is an old-school petrol engine, with emissions systems limited to catalytic converters.
• EGR valve: It does have one. As mentioned, it tends to get dirty, but it is easy to clean.

Dual-mass flywheel

Since the Honda Legend with this engine came with an automatic transmission in 99% of cases, it does not have a dual-mass flywheel. The automatic transmission uses a torque converter (hydraulic torque converter).

Parts prices: Consumables (filters, spark plugs, brake pads) are not expensive (depends on the market). However, specific engine parts (sensors, engine mounts which are hydraulic and active) can be very expensive and harder to source because the model is relatively rare.

Fuel consumption and performance

City and highway driving

Let’s be honest – this is a heavy sedan with a V6 engine and an old automatic gearbox.
City driving: Expect fuel consumption between 14 and 18 l/100 km. In heavy winter traffic, it can go even higher.
Open road: This is where the engine shines. Consumption drops to 9 to 11 l/100 km.
Motorway: At 130 km/h, the engine spins at relatively low revs (around 2500–2800 rpm), is inaudible in the cabin and uses about 10–11 liters.

Is the engine “lazy”?

With 205 hp and almost 300 Nm of torque, the engine is not weak, but the car is heavy and well insulated. Acceleration is linear and “gentlemanly”. You don’t get that “kick in the back” like with turbo diesels, but rather a constant, strong pull all the way to the redline. It is more than adequate for overtaking, provided you press the accelerator all the way (kick-down).

Additional options and modifications

LPG conversion

YES. This engine is an ideal candidate for LPG. The intake manifold is metal, and the injection is indirect. With a quality sequential LPG system, running costs become much more acceptable.
Important note: Honda engines require mechanical valve adjustment. On petrol this is done less frequently, but if you run on LPG, make sure to check valve clearances every 30,000–40,000 km to prevent the valves from “sinking” into their seats and losing compression.

ECU remap (Stage 1)

On naturally aspirated petrol engines, remapping is generally a waste of money. You might gain 5–8 hp and slightly better throttle response, but you won’t notice a significant difference in performance. It’s better to invest that money in proper maintenance.

Transmission

The C35A2 engine in the Legend KA9 comes with a 4-speed automatic transmission. It is a classic Honda automatic which is very robust.

Transmission issues and maintenance

• Most common issues: The gearbox can become harsh when shifting if the oil is not changed regularly. The solenoids inside the transmission can get dirty.
• Maintenance: The transmission fluid (ATF) should be changed every 40,000 to 60,000 km. Use only genuine Honda fluid (ATF-Z1 or the newer DW-1) or top-quality equivalents that meet that specification. Do not use universal ATF without checking compatibility.
• Clutch replacement: Since this is an automatic, there is no clutch disc and pressure plate. A full transmission rebuild (if it comes to that) is very expensive (depends on the market), often more than the car is worth.

Buying used and conclusion

What to check before buying?

1. Cold start: The engine should start immediately and idle smoothly. Any rattling may indicate the need for valve adjustment.
2. Exhaust smoke: Blue smoke at startup = valve stem seals. Blue smoke under throttle = piston rings (engine needs a rebuild).
3. Transmission: It should shift gears imperceptibly, without jolts when shifting from P to D or R. Check the color of the transmission fluid on the dipstick – it should be red or light pink, never black or smelling burnt.
4. Oil leaks: Inspect the engine from underneath, especially the joint between engine and transmission.
5. Vibrations: Engine mounts are expensive. If the car shakes at idle while in “D”, the mounts are probably worn out.

Conclusion

The Honda C35A2 is an engine from the “golden era” of Japanese engineering. It is intended for drivers who want top-notch comfort, silence and exclusivity at the cost of high fuel consumption. It is not for those looking for a sports car or cheap city driving. If you find a well-maintained example and install LPG, you’ll get a “land yacht” whose comfort rivals that of much more expensive modern cars.