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J&W Auto Repair

AUTOMOTIVE: The diesel engine

By Wyatt Nettles, J&W Repair

Diesel engines used to be simple. All you needed was fuel and air. Diesel engines have high compression, which develops heat; heat fires fuel; no spark needed. All the electrical needed was for a starter and lights. Fuel was turned on by pushing a cable and off by pulling. The starter cranked the engine so you had to have batteries and starters.

We use diesels for more power and better economy. But with today’s cost of repairs, you better use them for what they were intended because the repairs will out-cost the fuel savings. But if you are using your vehicle for work, it will pay the difference.

Today’s diesels run low on compression but use turbos to boost compression. Most engines have glow plugs or intake heaters for better starting. Block heaters are still available for help on cold mornings.

With the use of computers, you now have better emission control. They use catalytic converters with sensors to read and control emissions.  With the addition of DEF – Diesel Exhaust Fluid – the exhaust is very clean, but causes a lot more problems. There is a lot more testing and expensive parts when there is a problem with the emissions.

Now to the fuel system on newer trucks. All injectors are managed by the computer. Some engines use a high pressure oil pump to operate injection. Now they use high pressure fuel with direct injection – just a lot more testing and headaches for our technicians.