The Worst Engines of All Time

Since the inception of the automobile, there have been so many different engines. Some of them were marvelous of engineering, and others a nightmare. As engines progress, they tend to get more complex and when they have a problem, resolving the problem can be very difficult. An engine problem can vary from a simple repair to requiring the engine to come fully out of the car and have either a major service or a replacement.
This list comprises engines that have inherent flaws, are unreliable and some because they were recalled for defects.

19. Chrysler 2.7 V6

Various Chrysler models from 1998 to 2007 had the LH engine, produced in 2.7 liter and 3.2 liter variants. Some years after purchase, several customers started to complain about the engine, because of a large amount of sludge buildup within the crankcase. Turns out that a poorly designed water pump allowed coolant to leak into the crankcase, turning the oil into a gel and blocking oil passages. That could lead to a complete engine break down.

18. Hyundai Theta II

Nearly 1.7 million cars equipped with the Theta II engine were recalled to factory. The problem was that pieces of metal, resultant from a deburring process to remove machining debris from the crankshaft, interfered with the oil flow through the connecting rod bearings.

17. BMW N63

The N63 is one of the least reliable BMW engines. This engine suffered from various component failures, like: high oil consumption, turbocharger failures, leaky valve stem seals, coolant leaks, carbon buildup issues, timing chain failures, and fuel injector failures. The N63 is an expensive engine to maintain.

16. Yugo 55

The Yugo 55 1.1 liter carbureted engine had one of the worst reliability ratings in history. The timing belt needed to be replaced every 40,000 miles to reduce the risk of it snapping and destroying the engine.

15. Toyota 1ZZ-FE

The 1ZZ engine is probably the least reliable engine Toyota ever built. This engine burned a lot of oil, clogging up the catalytic converter and making both the engine and the cat useless.

14. Cadillac Northstar

The Cadillac Northstar engine had a problem of cylinder head gasket failure. This was due to overheating and cylinder head stud failure.

13. Subaru EJ25

The EJ naturally-aspirated 2.5-liter were fitted with poor quality pistons and didn’t have very good oil passages for the rod bearings. Additionally, it had head gasket failures.

12. Jaguar V12

The Jaguar V12 engine had heating problems. The ignition and fuel systems were in close proximity to one another, which would cause them to fail over time. The electric system was also too close to the engine, causing it to unravel and fry from the heat.

11. Mazda Renesis

The engine housings and apex seals of the Mazda Renesis are low quality, which makes them to fail. This engine is fragile and way too thirsty.

10. Chevrolet Cosworth Vega Z09

The Cosworth-engineered dual-overhead camshaft engine had poor reliability, worse longevity, and low survival rates. The blocks were cast with a high silicon content that wore out quickly.

9. The Iron Duke

This engine gets on this list just because of how underpowered it is. A 2.5 liter that produces just 85 HP.

8. Oldsmobile Diesel

This diesel engine was based on an Oldsmobile gasoline 350 V8. The problem with this engine was blown head gaskets, due to heads that were secured by the same 10-bolt pattern as the gasoline version, which proved insufficient as the bolts began to stretch from the high compression required for diesel combustion.

7. Porsche MA1.75

The 2014 Porsche 911 GT3 engine had an engineering fault. The connecting rod bolts failed, making the 3.8-liter engine to break down. Fortunately, Porsche had all the engines replaced under warranty.

6. Early GM LT4 Supercharged

The Chevrolet Corvette Z06 engine was incapable of shedding heat quickly enough, and the track-focused car couldn’t do more than a couple of laps at a time.

5. Ford 1.0-liter EcoBoost

The Ford 1.0-liter EcoBoost is a small 3-cylinder engine. However, the problem is not its size but the oily parts inside it. The oil pump is driven by a belt exposed to the engine oil causing bits of rubber to get into the oil, clog the pickup tube, and starve the engine of oil.

4. GM 3.6 High Feature Engine

The 2.8 and 3.6 liter variants of this widely used engine platform sometimes developed a serious issue in year model cars from 2007 to 2010 in particular. The main problem with this engine is the timing chain, that if left unchecked, engine misfires may occur and metal shavings will show up in the oil.

3. Nissan 1.5/1.8

Unlike many Japanese engines, the Nissan 1.5/1.8 are not reliable. Due to their wear-prone piston rings, these engines' oil consumption rate exceeds 1 l/1000 km, and sometimes even 1.5 l/1000 km, and with such a little oil sump, engine failure can be simply a matter of time.

2. Volkswagen 1.4/1.6 FSI

This Volkswagen engine equipped various VW Group models. These engines had terrible durability from the start of production. The main issues were carbon deposits in the intake system and valves, faulty and expensive sensors, and timing chains.

1. Cadillac V8-6-4

The infamous Cadillac L62 engine with cylinder deactivation technology was a horrible engine. The engine was designed to shut off two or four cylinders when not under load in order to save fuel. On the other hand, the horrific drivability and hesitation weren’t worth it.