Subaru Engine (EZ30R, EZ30D) Service & Repair Manual

Are you looking for a detailed Subaru EZ30 engine repair manual? Our Service & Repair Manual provides all the necessary data for diagnostics, repair and maintenance of the EZ30D (Phase 1) and EZ30R (Phase 2) engines installed on the Subaru Legacy, Outback, Tribeca and B9 Tribeca.

What does the manual include?

✔ Full technical specifications of the EZ30D and EZ30R engines

✔ Cooling, lubrication, fuel and timing system diagrams

✔ Maintenance schedule: oil, spark plug, filter, timing belt and chain replacement

✔ Malfunction diagnostics: error codes, causes and solutions

✔ Engine disassembly and assembly: step-by-step instructions with illustrations

✔ Typical problems: overheating, increased oil consumption, failure of phase regulators

📥 You can download the manual or read the online version on our website.

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1. Engine overheating

Causes:

Air in the cooling system

Clogged radiator

Failure of the thermostat

Breakthrough of the cylinder head gasket (especially for EZ30D)

✅ Solution:

Regularly check the coolant level

Clean the radiators and change the antifreeze according to the regulations

Install a high-quality thermostat

2. Increased oil consumption

Causes:

Worn piston rings

Problems with crankcase ventilation

Leaks through crankshaft seals and valve cover gaskets

✅ Solution:

Use high-quality oil with replacement every 5,000–7,000 km

Monitor the oil level

If consumption is high — decoking or major repairs

3. Problems with AVCS phase regulators (EZ30R)

Symptoms:

Diesel sound when starting

Loss of power and increased fuel consumption

Errors P0011, P0021 (AVCS problems)

✅ Solution:

Use high-quality oil (not thicker than 5W-30/40)

Flush the lubrication system and change the oil regularly

If it fails, replace the phase regulators

4. Complexity of repair and high cost of maintenance

Problems:

Time-consuming process of replacing spark plugs (requires disassembling the intake manifold)

The engine is difficult to repair without experience with boxer engines

Few spare parts, especially for the EZ30D (Phase 1)

✅ Solution:

Have the engine serviced at specialized Subaru services

Use only original or proven analogs of spare parts

Conclusion

The Subaru EZ30 engine is a reliable and powerful engine, but it requires high-quality oil, a serviceable cooling system and regular maintenance. The main problems are related to overheating, oil consumption and phase regulators on the EZ30R. If you monitor the engine's condition, it will last 300,000+ km without any problems.