What Might Be Wrong With That Diesel Engine

A diesel-powered engine is often chosen when a car or truck needs maximum towing capacity, as a diesel engine usually provides more power versus more speed. A diesel engine also converts heat to power, so it typically runs more efficiently than a petrol engine, which just wastes the heat it produces.

While a diesel engine may be stronger and more efficient overall, it may suffer some of the same problems as a standard petrol engine, and some problems that are unique to diesel engines because of how they're designed. Note a few troubleshooting tips so you know where to start looking when your diesel engine is acting up and what it may need by way of repairs.

Engine cranks, but won't start

Any gasoline engine may refuse to turn over if the fuel pump is bad; this pump takes fuel from the gas tank and delivers it to the engine as needed. When this pump fails, the engine isn't getting petrol and won't start. However, a diesel engine that won't start may be lacking heat; diesel engines use heat to start, versus a spark used by standard petrol engines.

To get this needed heat, diesel engines compress fuel in order to heat it up. If the fuel compressor goes bad, there is no heat and the engine won't start. A diesel engine may also rely on what are called glow plugs. This plug creates a small bit of heat that is also needed to start the engine on very cold days. If the engine cranks but won't start during wintertime, check the glow plug for needed replacement.

Engine starts but won't idle

Any engine may need an adjustment to the timing of the idle so that it doesn't stall. However, a diesel engine may need some continued heat after it starts and before it gets warm, to keep it from stalling. The glow plugs mentioned above may simply be going off too soon, not giving the engine the heat it needs for continuous power. The glow plugs may not need replacing but the controls that monitor the timing of the plugs may need to replaced.

Engine idles rough but clears after warming up

If the engine idles roughly but then seems to be much smoother after it warms up, this usually means there is incorrect or contaminated fuel in the lines. The engine works hard to stay functioning with poor-quality fuel but once that fuel warms up, the engine may be able to more readily convert it to power. Drain the tank and refill it with high-quality fuel and note if this addresses the problem.