More about diesel

Are modern diesel engines less reliable than their ancestors?

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There are a lot of good things about modern diesel engines.

New diesel engines use the common rail diesel system.
Put simply this is a high pressure system which results in better fuel usage.

common rail diesel

The setup

Common rail diesel engines have been developed to meet stricter emissions regulations brought in in the USA and Europe.

Another modification in new diesel engines is the addition of a Diesel Particulate Filter.
The aim of this filter is to remove or reduce the tiny diesel particulates from the exhaust which would otherwise go into the atmosphere.

‘Old’ diesel engines used diesel high in sulphur.

This high-sulphur fuel was good for engine protection (good lubrication) but a disaster for the environment.
It added to acid-rain and breathing problems.

diesel causes acid rain
Sulfur has been reduced in diesel fuel (probably adding to the cost) but reducing environmental impact.


Modern diesel engines are machined to much closer tolerances and have better lubricating systems.
Today’s diesel engine has an expected lifespan of  a quarter of a million miles or more.


Earlier diesel engines needed recon at 100k miles.
New oils and better quality control have helped to push reliability much further in today’s common rail diesel engine.
Parts are machined to much closer tolerances (less variation)  and electronic control means better timing and better control.

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