There are no unequivocally good or bad motors in the world. They would never be in demand. But big problems – limited service life, frequent breakdowns, expensive repairs – are common.
And the problem is not that the manufacturers knowingly produce bad engines. It is in the expectations of the owners. If a sports car driver understands that the engine will not work long under serious loads, the long haul driver expects trouble-free mileage of almost a million kilometers.
Engineer Kirill Yurovsky made a rating of the most unreliable engines, which you should avoid when buying a car. We will also find out why this happens and who is to blame.
Who is to blame for the poor quality of engines
Automakers are constantly upgrading engines to eliminate flaws identified during operation. And if the engines on new cars will show themselves in about five years. How an engine in a used car will behave is unknown. And even the famous brands misfire.
So why does this happen? Here are a few reasons:
- Exaggerated demands on well-known manufacturers. Car owners are used to the fact that foreign manufacturers show excellent quality in comparison with the Russian brands. Therefore, any breakdown is perceived critically.
- The high cost of repair work. The cost of replacing parts for some engines is comparable to the cost of an overhaul of a domestic engine.
- Exhaustion of the engine life. Cars used in cabs or car sharing are often sold after a long period of use or after serious problems have arisen. These problems are often hidden from the buyer.
At the same time, you should not forget about regular maintenance, and then the engine will work for a long time.
Diesel, gasoline – which is worse?
Diesel engines are powerful, reliable, economical and affordable in service against the background of the frequent breakdowns of gasoline engines. But even among them there are “bad” motors, which have problems up to 100 thousand km of run.
Gasoline units are the most common for passenger cars. And this is caused not by high performance qualities, but by the fact that it is necessary to create (design) less pressure to burn the mixture, to produce less costs. Such motors are produced in various modifications – injector, turbocharged, atmospheric, four-stroke and other models. Which, on the one hand, expands the possibilities of choice, but on the other hand – makes it even more complicated. After all, each model has its own disadvantages and advantages.
Top Bad Engines
The opinion of a bad or reliable engine is formed on the basis of accumulated information on the most frequent failures of the same engines. No one will say, never buy this family, but these models show excellent quality. After all, 1,000 of them can serve their intended service life without any complaints, and 10 of them will fail in a year or two.
When compiling the list of bad motors, we relied on the opinions of auto experts. We do not aim to denigrate the famous companies, but we want to highlight the frequently occurring problems.
N47D20
The diesel engines that were installed in BMW and Mini vehicles between 2007 and 2017 fall into the risk zone. In particular, BMW series 1-4, Mini Cooper, X1, X3, X5 and other models with engines from 1.6 to 2 liters.
Negative features include:
- Loudness. Roaring and rattling are constant components. And even if someone likes this sound, most of them are annoyed.
- Timing chain stretching. A short run of 60-80 thousand km – and the chain is stretched. To change it you need to remove the engine. But it is extra cost.
- Weak manifold flaps. With time they crumble and break, at the same time damaging cylinders. Therefore, it is necessary to constantly monitor them.
- Nozzles. Their service life does not reach even up to 100 thousand kilometers.
Although excellent power with low fuel consumption is noted, but this saving does not always cover the cost of repairs. Therefore, it is necessary to constantly diagnose the engine.
N46B20
This is an inline four, which is characterized by power of 143 hp and a displacement of 2 liters. It is installed on BMW series 1, 3, X1, X3, Z4. Its disadvantages include:
- High oil consumption – up to 1 liter per 1 thousand km after 70-90 thousand km of run. It occurs due to caking of piston rings, application of low-quality oil scraper caps (must be replaced after 50 ths km).
- Loss of engine dynamics. Timing chain loses proper tension because of plastic chain tensioners.
- Vibration at idle. Caused by low traction and jumping revs due to failure of Vanos system.
Also after 50 thou km it is necessary to change plugs and valve cover gasket, vacuum pump fails. Noise may be produced after 100k km.
N63B44
Turbocharged engine with a volume of 4.4 liters, V8 configuration, which produces 405 horsepower. It can be found in BMW 5, 6, 7 series, X5 and X6 cars.
The main disadvantages:
- Increased oil consumption. It occurs due to contamination of the piston grooves. It can appear on motors which have passed only 50 thousand km.
- Hydraulic shock after a long idle time. It occurs because of inadequate injectors.
Also ignition skips may occur due to poor-quality spark plugs.
4D55/4D56
Four-cylinder diesel engine with a capacity of 2.3-2.5 liters, which is designed for Mitsubishi cars. This model has been produced since the 80s and it seemed to be reliable. But the modernization has failed, because of which the capacity has increased, but overpowering of the unit has appeared. In particular, cracks of cylinder head, breakage of timing belt, overheating, fractures of camshaft, cracks in the cylinder block, etc.
Especially, it is necessary to be very careful in regions with cold climate. The engines there often break down to 100 thousand km run. Which is very little for a diesel engine.
M272/M273
The advanced gasoline engines with a capacity of 2.5-3.5 liters, which give up to 316 hp. Fitted on Mercedes V6, V8. The high technical characteristics (powerful traction, fuel efficiency) and advanced solutions for 2004 (all-aluminum, 4 valves, alusyl cylinders) were supposed to provide quality. But in the end…
Familiar problems:
- Timing chain stretching;
- vibration at mileage less than 60k miles;
- Intake manifold failure;
- oil radiator leaking;
- clogged ventilation system;
- burrs in a piston group.
In order to perform repair work it is necessary to completely overhaul the engine.
Over time, the manufacturer recalled cars and fixed the problems, but the impression was spoiled.
EA111
The pursuit of power and efficiency has also failed the manufacturers of gasoline units for Volkswagen, which were installed on the Skoda Rapid, Octavia, Yeti, Fabia and VW Polo, Jetta. Currently, an improved version of the unit is used, which does not have such problems.
The family of motors is known since 2005 and is divided into two types: turbocharged (TSI) and atmospheric (TFSI). But the disadvantages are found in both versions.
On small turbocharged engines (volume of 1.2 liters) the biggest nagging has caused chain failure, which went less than 30 thousand km. As well as problems with the electric turbine control actuator.
For units 1.4 TSI – detonation when using gasoline below 98 mark, the destruction of pistons at high load and contamination of the pump and filters. The engine was not ready to use Russian gasoline, which caused a lot of problems. As always the timing chain failed. Though it covered a mileage of about 100 thousand kilometers, it could break and bend the valves.
The atmospheric units showed the same problem with the timing chain, there were scuffing in the piston group, it was necessary to change crankshaft liners frequently because of the low service life. The main problem of car mechanics was “knocking on the CFNA”.
EP6
The unit from Peugeot-Citroen, which was released in 2005 with the help of the BMW Group. It was produced with the displacement of 1.4-1.6 liters and output of 95-270 hp. It was installed on many Peugeot, Citroen and even BMW Mini Cooper cars. The quality was good and the engines were even awarded the Engine of the Year award.
The appearance of problems depends on timely maintenance. But often the negative factors start manifesting themselves after 100,000 km run. The only exception is the unit EP6 CDTM, which has been adapted for the Russian market. In other cases, it is noted:
- Stretching of the timing chain up to 45 thousand km. There was noise at idle. In subsequent versions it was eliminated.
- Valvetronic malfunctions due to fouling of the valves. Caused by high fuel quality requirements.
- Frost penetration in the crankcase. The problem was eliminated due to additional heating.
But oil starvation became the main problem. Falling oil level caused deterioration of gaskets, seals, failure of oil pump. With maintenance every 5-6 thousand km it was possible to drive long enough. But it is almost impossible to find an engine in good condition on the aftermarket.
EcoBoost
The whole range of 150-240 hp 1,5, 1,6 and 2 liters engines is related to the unreliable ones. These engines are used for Ford cars, also installed on Mazda series 3-6, CX7. They have typical problems for turbocharged units. In particular, pistons melting, problems with the injection system and cracking of cylinder baffles. It is connected with environmental requirements. The stricter they are, the lower is the operational reliability.
