Toyota AZ Engine Family – What You Need to Know

Categories: Cylinder Head Tips

The Toyota AZ engine family is a series of straight-4 piston engines which use an aluminum engine block that’s made with aluminum DOHC cylinder heads and cast iron cylinder liners. The technology used in this series of engines is very impressive, which is why they were used for many years in Toyota vehicles. The AZ was the replacement for the previous S engine and was succeeded by the AR engine. Today, we’re going to take a look at the various engines in the Toyota AZ engine family and the differences and key features of each of these engines.


1AZ-FE Engine Overview

When the AZ series first came to replace the S Series in 2000, the first displacement engine in the range was the 2.0-liter 1AZ-FE engine. It was a very advanced engine for that time and uses an aluminum cylinder block and cast iron liners. The engine is balanced with eight counterweights and uses a forged steel crankshaft, which is attached with five bearings. Adding balancing shafts between the first two bearings was a big development in the engine building process and aimed to reduce the engine vibration. In addition, helical gears were made from polymeric material to reduce the noise given off by the engine. A common concern with this engine was the cylinder head bolt threads wearing out and a high level of vibration when on an idle rpm level. That being said, this engine is typically reliable for about 200,000 miles.


1AZ-FSE Engine Overview

The 1AZ-FSE is a modified version of the above engine and is a direct fuel injection engine that uses the company’s D-4 direct injection system. It has a compression ratio of 10.5:1 and offers up to 148 hp at 5700 rpm. These two engines in the series offer high efficiency and fuel economy, as well as lower noise and vibration levels when compared to previous options from the company. The lightweight design and compactness of the engine means it’s ideal for a variety of applications.


2AZ-FE Engine Overview

This engine was also produced from the year 2000 and is a 2.4-liter inline-four engine which offers a larger displacement version of the two engines we’ve shared above. The aim of this engine was to replace the 5s engine that was previously used within the company. Similar to the 1AZ-FE, this engine has an aluminum cylinder block with sleeves, but it offers a larger cylinder bore with bigger pistons. A timing chain is used for the camshaft rotation, and there are no hydraulic lifters present in the design.

About every 60,000 miles, users of this engine will need to adjust the valve clearance. While the engine is considered reliable, it does have a high oil consumption level when compared to other similar engines. This high oil usage is due to issues with the piston rings in the design within the North American market.


2AZ-FSE Engine Overview

This modified version of the engine we detailed above uses the Toyota D4 direct fuel injection system. The compression ratio is 11.0:1, which is much higher than other options on the market and helps to offer 161 hp (120 kW) at 5800 rpm and 170 lb ft of torque at 3800 rpm. One concern with this collection of engines is the cylinder head bolt threads, which often wear out within the back three bolts. You may notice coolant leakage at the back of the engine, which is a good indication that there is an issue in this area. The cylinder block was redesigned in 2007, which stopped these leakage issues and reduced reports of overheating.


2AZ-FXE Engine Overview

This 2.4-liter engine uses an Atkinson cycle. While it has the same bore and stroke as the engines we’ve shared above, the pistons and camshafts were designed especially for this engine model and it was intended for use within hybrid vehicles. Cars that used this engine included the Toyota Camry Hybrid AHV40, Estima Hybrid and Lexus HS 250h. It offers an impressive 147 hp at 6,000 rpm and 138 lb ft of torque at 4,400 rpm. One thing to keep in mind with this group of engines is that the cylinder block isn’t rebuildable. That means if you do experience damage to the cylinder block, then you will have to replace it instead of having the option to repair it. Many of the issues within this group are similar to those of the 1AZ-FE engine series, but you’ll find that it’s still a very reliable engine option which offers drivers about 180,000 to 200,000 miles of use.



The 3AZ-FSXE is an analogue version of the 2AZ-FXE for the Chinese market which is used within the Camry 40 Hybrid CHN. When reading the numbers and letters within this engine family, the first digit refers to the generation of the engine, so this is the third generation within the engine family. The F refers to the economy narrow-angle DOHC and the E is the multi point fuel injection. Toyota Camrys typically get between 200,000 and 300,000 miles of use, showing how resilient and well-manufactured this engine is. This vehicle also had a good miles per gallon (MPG) rating which is why it’s one of the companies top sellers and continues to be redesigned to meet the needs of today’s market.


AZ Engine Family | Concluding Thoughts

The Toyota AZ engine family was an incredibly popular and innovative addition to the company’s engine range and the market in general. The technology used in these engines paved the way for today’s modern engines, and many of the additions to the engines were considered ground-breaking at the time. These engines typically last 200,000 miles when well-maintained, but you’ll want to make sure you are aware of some of the common problems to avoid these or fix issues as they occur. Toyota has been a market leader for many years within the industry due to the company’s willingness to continue to develop new technology and build engines that will be reliable for drivers around the world.


Toyota Cylinder Heads from Clearwater Cylinder

If you are the owner of a Toyota, then please call us so we can help you select the right cylinder heads for your specific vehicle. Clearwater Cylinder Head offers both refurbished and new Toyota cylinder heads for sale. The casting number on your Toyota engine or existing cylinder head will help us to select compatible heads for your Toyota.