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5 Most Unreliable Engines Toyota Ever Made (5 From Honda)

Aug 20, 2023Aug 20, 2023

When it comes to reliable engines, even Toyota and Honda, two of the most dependable automakers, have fallen short on occasion.

When it comes to reliable cars, Japanese automakers – led by Toyota and Honda – are second to none. After all, Toyota and Honda are among the 10 most reliable car brands that sell the most reliable cars and engines. That reputation has earned the two brands customer loyalty that’s unmatched in terms of unit sales per year. Today, Toyota and Honda are by far two of the most popular Japanese brands in the world.

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However, that doesn’t mean there haven’t been bad eggs in the Toyota and Honda lineups over the years. The two brands have an equal share of unreliable engines that failed to hit the mark. Not that these engines had poor build quality. Instead, their reliability issues stemmed from other problems like blown head gaskets, excess oil consumption, oil dilution, and more. Here are the most unreliable engines from Toyota and Honda.

Rarely does Toyota produce unreliable engines, but the 3VZ-E is one of the worst Japanese engines, infamous for its set of reliability problems. Introduced in 1988, the 3.0-liter V6 engine found its way under the hood of the 4Runner and the Toyota Pickup, where it made a paltry 150 hp and 180 lb-ft of torque.

Power aside, the 3VZ-E has the worst reputation for durability. While the engine’s cast iron block does offer solid strength, the combination with an aluminum cylinder head causes serious head gasket issues. After all, leaking head gaskets is one of the most reported problems with this engine. This led to Toyota extending warranty coverage for head gaskets to eight years or 100,000 miles. Other problems include failing timing belts that need replacing every 80,000-100,000 miles, burnt exhaust valves, and failing starter contacts.

The 1.5-liter turbo Earth Dreams is one of the worst modern engines. Equipped with a host of technologies, this engine has proved an absolute nightmare for owners who must cope with problems such as diluted oil, excess gas odors in the cabin, and the sensation that you’re driving a washing machine.

The engine, featuring Honda’s Earth Dreams Technology, uses GDI (gasoline direct injection) to improve fuel economy and increase horsepower. Like other GDI motors, injectors feed gas into the engine via a high-pressure fuel pump, meaning that some fuel blows by the piston rings and makes its way into the crankcase, mixing with the engine oil. This compromises the oil’s viscosity and cuts down its lubricating benefits, resulting in long-term damage to the engine components. Although Honda tried passing it off as a problem only during cold climates or driving for short trips, the Japanese automaker eventually extended the engine warranty to cover the inevitable engine breakdowns caused by oil dilution.

Produced from 1986 to 1992, the 7M-GTE is highly popular for its use in the Mk3 Toyota Supra. However, the engine doesn’t have the same reputation as the legendary 2JZ that succeeded it. While you may be tempted to think it’s because of its underwhelming power and performance, that’s not the case. The 7M-GTE had a poor reputation for reliability, caused by a factory defect.

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During development, Toyota intended to use a head gasket containing asbestos, but shortly before the 7M-GTE’s launch, there was a ban on asbestos products in the automotive industry. Lacking enough time for research and development, Toyota resolved to use an asbestos-free head gasket that crumbled under stress. This resulted in failing head gaskets that caused oil and coolants to mix, causing rod bearing failures.

The 3.5-liter J35Z8 is a member of Honda’s J-Series V6 engine family that powered several cars, including the Accord, Pilot, and Odyssey. One of the most common complaints with the J35Z8 engine is its tendency to burn excessive oil. The problem was so severe that owners sued Honda for the problem.

The lawsuit claimed that over 1.5 million cars that burned oil excessively required frequent spark plug replacements, and the Japanese automaker hid it from customers. Honda initially denied this allegation, despite issuing a TSB (Technical Service Bulletin) in 2013 that acknowledged the problem. But two years later, Honda agreed to settle the class-action suit. Part of the settlement included an extended powertrain warranty for eight years from the time of purchase for the affected models.

Toyota introduced the 1ZZ-FE in 1998 and remained in production until 2008. The naturally aspirated inline-four engine had lackluster power, producing 120-130 hp and 122-126 lb-ft of torque, but the most concerning issue with the engine was its reliability problems.

Excess oil consumption was the main problem affecting the 1ZZ-FE engine, caused by the piston and piston ring design flaws. Toyota used small pistons, and the larger piston rings did nothing to improve the situation. The piston rings would wear down over time, allowing excess oil to leak through the rings. Toyota acknowledged the problem, fixed it in 2005, and gave a six-year or 100,000-mile warranty. This means pre-2006 models still have this problem. Other common issues with the 1ZZ-FE include failing timing chain tensioner and Engine Control Module.

Production of the D-Series engine kick-started in 1984 with the D15, followed by the D16 two years later. It powered several Honda cars, including the Integra, Civic, Del Sol, CRX, and HRV. Although the D16 inline-four engine is highly popular among tuners, earlier versions were less desirable due to various problems.

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Common issues with the D16 engine include oil leaks and engine misfires. Rough idle is another highly reported issue, usually caused by a faulty throttle body, dirty idle control valve, or faulty oxygen sensor. The engine also suffered from worn exhaust manifolds and crankshaft issues.

Introduced in 2007, the 2ZR-FE is yet another problem-plagued Toyota engine that replaced the 1ZZ-FE. It is a common engine in the Prius, Corolla, Scion, and Matrix. Like its predecessor, the 2ZR-FE inline-four engine had an appetite for oil consumption, especially in the 2008-2010 Corolla models.

The oil consumption issue originated from faulty piston rings that allowed oil to leak into the combustion chamber and burn alongside the normal air/fuel mixture. People who had cars with the 2ZR-FE engine also reported a failing coolant pump when the engine clocked about 30,000 miles. Toyota acknowledged the problem and covered it in most factory warranties. Post-2007 engines also had a problem with the valvematic system, which was caused by dirt entering the intake manifold.

The R18 inline-four engine came to life following the release of the eighth-generation Honda Civic in 2005. It wasn’t long before the Civic developed a bad name due to a casting problem that caused the engine block to crack, allowing coolant to seep out and causing the engine to overheat.

Hundreds of complaints rolled out regarding cracked engine blocks, which cost owners up to $7,000 in repairs and labor costs. Junkyards became overloaded, with many Honda owners discarding their cars due to blown engines. Although Honda sent warranty extension letters in 2014, these warranties have since expired, leaving unlucky owners with cracked engine blocks. This problem affected the 2006–2009 Civics, which is why you should avoid them like the plague.

Produced from 1993-2007, the 1MZ-FE replaced the 3VZ-FE engine and powered several models such as the Camry, Highlander, Avalon, and other Lexus models. Oil leaks and engine sludge build-up are common issues in the 1MZ-FE engine, which eventually led to its downfall.

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Engine sludge build-up was so prevalent in several models that it became the subject of class-action lawsuits and recalls. A bad knock sensor is another common occurrence in the 1MZ-FE, which Toyota addressed by replacing it altogether in the 3MZ-FE. Lastly, several owners reported issues with their EGR (Exhaust Gas Recirculation) that caused poor gas mileage and extreme gas odors inside and outside their cars.

Based on the F20 motor, the F22B is a member of the Honda F-family and the first F-Series engine to receive Honda’s revolutionary VTEC technology. Back then, the engine powered several models, including the Accord, Prelude, Odyssey, and Shuttle.

The F22B is also one of the most unreliable Honda engines, plagued with several problems. Firstly, the engine suffered from oil leaks caused by faulty oil seals and worn gaskets, especially in the 1994-1998 Honda Shuttle models. Transmission issues are another common issue, including delayed shifting, slipping gears, and complete transmission failure. Lastly, engine misfires are a prevalent problem in the F22B, in addition to worn-out crankshafts at around 100,000 miles.

Sources: Tuning Pro, Car Complaints, Honda Problems, and Toyota Owners Club

Dennis Kariuki is a tech enthusiast who writes for Previously, he wrote for .He likes covering the marriage between technology and cars. Besides that, he is big f1 fan. After working tirelessly through the week, you can be sure that on Sundays he is most likely enjoying and following motorsports events.

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