These Are The Worst Engines Of All Time

This one is personal for me. My big diesel ambulance is powered by Ford’s totally shitty 6-liter powerstroke. A couple of years ago, I experienced clogged EGR issues, and it’s cost me a few thousand dollars to rectify. When they’re running right, they are pretty decent, but they’re apt to leave you stranded if you look at them wrong.

There are ways to keep them happy, but they really don’t like it when you add more boost.

Here’s another Blue Oval special. The 2.0, 2.3, and 2.5-liter Lima, Ohio-built four-cylinder engines were about as uninspiring as they come. These engines powered everything from base model Mustangs and Pintos to Ranger pickups and Aerostar vans. It was used from 1974 to 1997, and made as little as 89 horsepower. The later turbocharged-and-intercooled versions in the Mustang SVO squeaked out 205 horses, but are definitely the exception that proves the rule.

The PRV can be OK if meticulously maintained, but they’re worth avoiding because of durability issues. I’ve also heard they’re a pain in the ass to work on. Especially when fitted to the rear-engine DeLorean. To cap it all off, they sound terrible and don’t make enough power to be fun.

Or maybe it’s the best engine of all time?

When the Chevrolet Corvette Z06 was introduced for the 2016 model year with a 650-horsepower supercharged V8, the world was totally hyped for it. Unfortunately, it quickly proved itself incapable of shedding heat quickly enough, and the track-focused car couldn’t do more than a couple of laps at a time. Once the cooling issues were sorted, the engine proved itself quite worthy, but the cooling engineering really let it down.

Perhaps one of the best driving cars of all time, Porsche’s new-for-2014 GT3 was let down by an engineering mistake which would allow connecting rod bolts to fail and the 3.8-liter engines to catastrophically fail. Thankfully Porsche owned up to the issue and had all of the engines replaced under warranty with better ones.

The notoriously bad 1981 introduction of Cadillac’s L62 engine with cylinder deactivation technology doesn’t have any champions. You’d be hard pressed to find a single person out there willing to say anything nice about this terrible engine. It was designed to shut off two or four cylinders when not under load in order to save fuel, and while it was 15 percent more fuel efficient than engines without this tech, the tradeoff in horrific drivability and hesitation weren’t worth it. Thankfully cylinder deactivation has come a long way in the last four decades.

Look, I actually kind of like the Iron Duke, because it’s solid as a damn rock. Much like Ford’s Lima 2.3, it was used for decades and still powers hundreds of thousands (maybe millions) of Americans on their daily commutes. It was introduced as a response to the oil crisis in the 1970s and was quickly pushed into production. It is about as under-stressed as an engine can be, making just 85 horsepower from 2.5-liters. It sounds terrible, and it’s just plain slow, but it’ll get you to your destination.

Here’s another terrible engine I have a lot of experience with. The 2-liter “pancake” Type 4 engine made by Volkswagen in the 1970s is a truly uninspiring hunk of shit. This aircooled monster made just 88 horsepower in 1976, and probably even less now. It revs to a whopping 4,300 RPM, and sounds like a Harley shovelhead got shoved in a garbage disposal. And that’s before you begin to talk about the dumb early Bosch fuel injection system that uses a points distributor and activates the injectors with a four-pointed trigger wheel. I absolutely adore the car as a whole, but the engine is a boat anchor.

The Cosworth-engineered dual-overhead cam engine for the Chevrolet Vega was a triumph when it was new but quickly developed a reputation for poor reliability, worse longevity, and low survival rates. The blocks were cast with a high silicon content, which isn’t unheard of, but it wasn’t developed well enough, and the bores wore out quickly. These engines can be rebuilt with steel sleeves to solve much of the issue, but that’s not ideal.

I will admit that I’m a sucker for a Mazda RX-8. They’re attractive cars with exceptional sporty handling, and typically amazing Mazda shifters. The Renesis was named “international engine of the year” in 2003, but history hasn’t been as kind.

The engine housings tend to be of a lower quality when compared to earlier RX-7 rotaries, and they can warp with mileage. The apex seals used in the Renesis are thinner and of a poorer quality than those in the earlier 13B. It was designed to be quieter and more emissions compliant than previous Mazda Wankels, but they’re more fragile and they’re way too thirsty for the modern driver.

The naturally-aspirated 2.5-liter version of Subaru’s venerable EJ engine is the one that kicked off all of the Subaru head gasket jokes. In addition to the gasket failures, these engines were fitted with poor quality hypereutectic pistons and didn’t have very good oil passages for the rod bearings. Bad all around.

When it’s working well it’s a decent engine, but these are prone to overheating and cylinder head stud failure. Often the overheating causes the cylinder head studs to fail, but not always. The studs were spec’d with too thin a thread on them, which is a problem. All of this leads to catastrophic cylinder head gasket failure. They also leak oil fairly often.

The 1ZZ engine is a wonderfully buzzy high-rev screamer of an engine, but it’s probably the least reliable engine Toyota ever built. These engines, particularly in the zippy sports car MR-Spyder, would burn oil at a tremendous rate, gumming up the catalytic converter and rendering both the engine and the cat useless. Toyota revised the piston design in later years, aiding, but not totally fixing the issue.

The N63 is widely regarded as the least reliable BMW engine, which is really saying something. Early models from 2008 to 2013 would suffer from high oil consumption, turbocharger failures, and leaky valve stem seals, likely all related. There were also the coolant leaks, carbon buildup issues, timing chain failures, and fuel injector failures. It’s an expensive engine to maintain, requiring frequent oil changes, spark plug replacements, and coolant flushes to stay running right. Hot V turbos are really hot, and really finicky.

Nearly 1.7 million vehicles fitted with the Theta II engine, both 2-liter and 2.4-liter varieties, were recalled for early catastrophic seizing failure. The problem has been blamed on a mechanical deburring process in the manufacturing facility meant to remove machining debris from the crankshaft. Pieces of metal interfere with the oil flow through the connecting rod bearings. The engines that didn’t fail were overly noisy. It was a quality control issue that cost Hyundai and Kia billions. Yikes.