a short description of
The K7M and K4M engines with the same working volume of 1.6 liters were developed by Renault with a view to budget cars.
In 1995, the Dacia factory in Romania started production of a simpler eight-valve K7M engine. The 16-valve K4M hit the conveyor belts in Turkey and Spain in 1999. And since 2013, it has been assembled here at AVTOVAZ.
The cylinder block is made of cast iron, the block head is made of aluminum. The pallet for increasing the rigidity of the structure is made of aluminum alloy and is bolted to the block without gasket.
Camshaft drive – belt, without devices for adjusting the phases. On the K7M the valves require adjustment and the K4M uses hydraulic valve lifters. The propulsion system is divided fuel injection.
K7M engine: many solutions look archaic.
1. Insufficient Power
Even if you compare it with peers. For example, the eight-valve K7M engine produces 87 horsepower, and the Volkswagen AKL series engine of the same volume (installed on the Volkswagen Golf IV and Skoda Octavia I) produces 100 horsepower.
At the turn of the century, the sixteen-valve K4M produced an acceptable (against the background of competitors) power of 102 horsepower. But emerging new models are already equipped with units with more advanced performance. For example, the 1.6-litre G4FC engine for Kia and Hyundai models develops 123 hp.
Cars equipped with these engines cannot boast of dynamic acceleration or high maximum speed. This is also apparent from the external speed characteristic – the graph of the distribution of power and torque depending on the crankshaft speed. It makes no sense to run the engine above 5000 rpm. There is a lot of noise, but the car does not accelerate anymore.
2. High fuel consumption
One of the reasons is the “short” gears in the boxes these engines are aggregated with. With this setting, a weak engine can dynamically accelerate the car. But this does not contribute to fuel consumption at all.
The K4M engine has no phase shifters (either on the intake or exhaust camshafts), which improve power characteristics and increase efficiency.
Both engines normally only run on gasoline with an octane rating of AI-95 and above. I had an eight-valve Renault Logan, now I drive an editorial Largus with a K4M engine. I tried to fill the 92nd petrol (and from a brand gas station) in both cars. The engines began to explode – it was necessary to hastily add high-octane fuel to the tank.
3. Attention to the timing drive:
Both engines (like most modern units) are plug-in. When the belt breaks, the pistons and valves collide. Therefore, the rules for replacing belts must be strictly observed.
The situation is aggravated by the fact that the timing belt also drives the coolant pump. Therefore, a malfunction of the “pump” (for example, caused by low-quality coolant) or a malfunction of the tensioner can lead to a broken belt and expensive engine repairs.
There are cases when the drive failed because snow got under the timing belt cover. And the belt suffered from oil coming through a leaking crankshaft oil seal.
4. Malfunctions in the engine management system
Most often, the ignition coils of the K7M engine fail due to cracks in the housing filled with compound. On Renault Duster crossovers, the coils have burned out because of moisture.
On both engines, the idle speed controls break.
The crankshaft position sensors proved unreliable. Although their failures were often caused by the mistakes of the soldiers who changed the claws.
There have been cases of engine temperature sensor failure, even during the warranty period.
5. Faults in the cooling system
The thermostat on these motors has the simplest design. Nevertheless, sometimes the resource does not exceed 20-30 thousand kilometers.
For example, the fourth is already installed on the Largus editorial office. Although the mileage has not yet reached 150 thousand km. In addition, frequent replacement of the thermostat leads to deformation of the plastic housing. So it is better to replace it with a metal one.
- There should always be a first aid kit and a fire extinguisher in the car. And on long trips, a tow rope is not superfluous.
- “Driving” can also be read on Viber.
The K7M and K4M units will operate 300,000 km or more without overhaul. However, they also have complaints.
Source: Z R
