2AZ-FE Oil Consumption Fix - How to Repair the Engine?

From its efficient fuel injectors to its improved camshaft profile, there are several reasons to love Toyota's 2AZ-FE engine. But like all impressive things, the engine has a few drawbacks, a common one being its proneness to excessive oil consumption. 

Key features and my opinion about the engine

• Production years:2000-2019
• Average lifespan of 2AZ-FE:210,000-240,000 miles
• Fuel supply type:port injection
• Power range:145-170 hp
• Fuel efficiency:average
• Engine block material:aluminum
• Engine reliability score:high
• The most common problems:weak head bolts up to 2006, heavy oil consumption, weak timing chain, problems with phaser

2AZ-FE and Excessive Oil Consumption - Causes

Toyota's 2AZ-FE is an injector-based engine which means it has a large vacuum that promotes excessive oil flow through the piston rings. Call it a design flaw, if you like, but the extra gap in the piston rings is almost always the cause of excessive oil consumption in 2AZ-FE engines. 

Many people may assume that this oil consumption is simply a result of the vehicle's age but several other uncommon factors can contribute to this problem.

One of them is improper maintenance. If your vehicle is poorly maintained, the engine oil may become dirty and contaminated, which makes it break down faster than normal. Not regularly replacing the oil filter can also cause this part to become clogged and ineffective, leading to increased oil consumption.

Another factor that can contribute to oil consumption in cars is driving habits. If a vehicle is frequently driven aggressively or at high speeds, it may use more oil than normal. Also, vehicles driven in stop-and-go traffic or idled may consume more oil than normal.

A faulty oil pump can cause increased oil consumption in Toyota cars since the oil pump is responsible for circulating oil throughout the engine, and if faulty, can cause the engine to consume more oil than usual. The reason for this ranges from a variety of issues, such as a faulty oil pump seal or a worn-out oil pump impeller.

How to Fix 2AZ-FE Oil Consumption

Your engine oil using more fuel than usual is always bad news, so what should you do? There are a few potential fixes you can try, and we'll discuss some of them: 

• Worn piston rings

Piston rings help seal the combustion chamber and prevent oil from interfering with the combustion process. Over time, these rings can become worn and oil passes through, leading to increased consumption.

To fix this problem, you will need to replace the piston rings. This repair is often challenging, so it is best to leave it to a trained mechanic. However, if you are experienced with engine repair, you can purchase a piston ring replacement kit and follow the instructions provided to replace the rings yourself. We'll also briefly outline the repair steps later in this article.

• Faulty PCV

Another potential cause of 2AZ-FE oil consumption is a faulty PCV (positive crankcase ventilation) valve. The PCV valve is responsible for regulating the pressure inside the crankcase, and a faulty valve can cause excess oil to be drawn into the combustion chamber. 

Fixing this problem often requires replacing the PCV valve. This is a relatively simple repair that can be done at home. Again, if you're unsure of how to proceed, have a mechanic handle it for you.

• Gasket seals

Consider checking the condition of your engine's gasket seals. These seals prevent oil from leaking out of the engine. If they are damaged or worn, they can allow oil to leak out, leading to decreased oil levels and increased consumption. You will need to replace the gasket seals to fix this problem.  

• Apply oil additives 

Lastly, consider using a high-quality oil additive, such as a compression restorer, to help seal any leaks or worn parts. This can help reduce oil consumption and improve your engine's overall performance.

Preventing 2AZ-FE Oil Consumption

If you have had to deal with excessive oil consumption, then you know how expensive fixing it can be. You also end up being frustrated as you may find yourself constantly topping off your oil levels. However, there are some steps you can take to prevent this issue and keep your engine performing optimally.

• Regularly check your oil levels and change your oil on time. The 2AZ-FE engine has a recommended oil change interval of every 5,000 miles or 6 months, whichever comes first.
• Use the correct type of oil for your engine. The 2AZ-FE engine requires 5W-30 oil, so be sure to use this specific type. Consult your owner's manual or dealership to determine the recommended oil type and grade.
• Avoid overfilling your engine with oil. Too much oil can cause it to leak or burn off, leading to decreased levels and potential engine damage. Always check your oil levels with a dipstick and fill to the appropriate level.
• Be mindful of short trips and excessive idling. The 2AZ-FE engine is designed for longer trips and can consume more oil on short trips or when idling for extended periods.
• Keep an eye on your engine's performance and watch for any unusual symptoms. Excessive oil consumption can be a sign of a bigger problem, such as a faulty piston ring or valve seal. If you notice any strange noises or decreased engine performance, have your vehicle checked by a mechanic.

By following these tips and regularly maintaining your vehicle, you can prevent excessive oil consumption that affects the smooth running of your 2AZ-FE engine.

Testing for Oil Consumption Level

Apart from looking out for symptoms like blue smoke or low compression, carrying out an engine oil consumption test can help you diagnose excessive oil consumption. 

Here are a few ways to go about that: 

• Check the oil level regularly

One of the easiest and most effective ways to monitor oil consumption is to regularly check the oil level using the dipstick. This should be done when the engine is cold and the vehicle is parked on level ground. If the oil level is consistently low, it may be a sign of excessive consumption.

• Use a consumption test

A more accurate method for testing oil consumption is to use a consumption test. This involves adding a certain amount of oil to the engine and then driving the vehicle for a specific time. The oil level is then checked again and the amount of oil consumed can be calculated.

• Check for external leaks

Excessive oil consumption can sometimes be caused by external leaks. To check for these, look for oil stains on the ground under the vehicle or any other visible signs of oil leakage.

• Consult with a mechanic

If you suspect excessive oil consumption but cannot find good proof, consult with a qualified mechanic. The professional can perform a more thorough inspection and diagnose any potential underlying issues.

Taking these steps can help ensure that any excessive oil consumption in a 2AZ-FE engine is detected and addressed before it causes further problems. Regular maintenance and monitoring can help extend the life of the engine and prevent costly repairs down the road.

Repairing the Piston Rings

If your car's oil level was more than 1 quart low after 1,200 miles during the consumption test, you should find the following repair procedure helpful: 

• Place the engine assembly on a stand after removing it.
• Remove the cylinder head and assembly.
• Find the connecting rods and remove the pistons.
• Inspect the piston pin, connecting rod, and bearings to know the replacement part numbers. This will also help you know if the parts can be reused.
• Install the new piston rings and assemble the engine following the reverse order in which you disassembled it.
• Install the engine assembly following the instructions in the repair manual.
• Test drive the car to be sure it is operating normally again.

There are several other procedures to adhere to while replacing the pistons and ring, all of which might be confusing for an inexperienced person. You will be better off leaving the entire process in the hands of a trusted mechanic.

Conclusion

Your 2AZ-FE engine isn't perfect but by identifying the root cause and following the proper steps, you can fix problems with oil consumption and prevent them from reoccurring. Regularly check and maintain your engine to ensure it is running at its optimal performance and to avoid any costly repairs in the future.