Myth or reality: Should you wait before turning off a diesel engine?

Moving a car does not always mean that the driver knows how to drive. Getting a car to move from one point to another without crashing is the minimum threshold, but there is also a series of knowledge and actions that complete the manual of a good, code-abiding driver of the road, which coexists harmoniously with the environment and, in addition, be careful with the vehicle.

The care of the car to which we refer is linked to the actions that are carried out when driving and which range from maintaining the correct tire pressure to not driving with the minimum fuel, including the protection of mechanical elements such as the brakes and the clutch. , pressing them when really necessary (do not brake with the clutch in cars with manual transmission). The list is long when it comes to car maintenance.

Among the topics to know to extend the useful life of vehicles is engine maintenance. In this case, gasoline engines require different means of protection compared to diesel engines. However, to implement these actions, ideas arise that may seem closer to popular beliefs than to real facts.

One of these questions, which we have been asked in recent weeks, is whether we should allow time to pass before shutting down a diesel engine. This is an idea that many drivers have and many have shared with people that at the end of a trip, they wait a few minutes before turning off the engine.

To find out this answer, we consulted Francisco Inglés Ñanculeo, professor at the Duoc UC School of Engineering and Natural Resources in Maipú.

According to the expert, taking those seconds is the right thing to do. “Yes, it can be influenced, although many vehicle and truck manufacturers do not give this indication as an engine shutdown process. It should be noted that these are supercharged engines with an air turbocharger, which allows a greater volumetric intake of compressed air into the engine, forcibly filling all cylinders constantly during operation.

The basic reason why it is advisable to let a few minutes pass is that “when you suddenly stop the engine, excessive wear can occur on the rings or bearings, because the oil pump automatically stops, cutting off the lubrication circuit to the turbo and generating wear of the same materials, which adds to the high temperatures to which the turbo itself can be subjected when in constant operation. If you give it some downtime while idling, such as using an electrical accessory called a Turbo Timer, you can compensate for this need for protection, thereby doing two big things: Lowering the rotational speeds of the turbo’s central axis, which when If the engine stops, it does not run for long without lubrication, and secondly, by keeping it idling after removing the ignition key, it can cool or lower its temperature to prevent the oil inside from burning , generating carbon or solid particles which, in the long term, will damage the turbo itself,” explains Inglés Ñanculeo.

Although it may seem obvious that all mechanical elements must be protected, in the specific case of bearings, bushings or bearings, it is “because if these parts wear out, the turbo bushing and the turbo rings The seal will begin to leak oil. towards the intake side of the engine, generating unwanted contamination in the intake with a hydrocarbon which can cause self-detonation and the diesel engine accelerates on its own at high revs, constantly smoking white, as it is excess oil that does it. does not burn 100% and even worse, this oil is responsible for lubricating the entire engine, and if it is not stopped quickly in this situation, the entire engine will melt due to the lack of lubrication that was burned during the combustion”.

In conclusion, when a person goes on a trip with a diesel car, it is advisable to let it idle, at the minimum speed that an engine can run, for about two minutes. This will allow the oil to lubricate the turbo and the rest of the parts to reduce their temperature, thus avoiding complications that would only make us spend money on repairs.

Myth or reality ? Reality.