Top 46 Diesel Truck Repair Shops in O'Fallon, MO

Symptoms of Diesel Truck Issues

Diesel trucks develop plenty of issues, like combustion issues, fuel efficiency changes, and electrical problems, to name a few. Still, most diesel truck problems come with specific symptoms that can indicate the culprit. Find out more about the common symptoms and causes of truck problems below.

Excessive Exhaust Smoke (Black, Blue, or White)

Cause: Black smoke may indicate a rich fuel mixture; blue smoke suggests burning oil due to worn seals or piston rings; white smoke can signal coolant leaks or incomplete combustion.

Hard Starting or No Start

Cause: A weak battery, faulty glow plugs, or low compression can make diesel engines difficult to start, especially in cold weather.

Loss of Power

Cause: Clogged fuel filters, a failing turbocharger, or air intake restrictions can reduce power output, especially under load.

Rough Idle or Misfires

Cause: Faulty injectors, a failing fuel pump, or poor-quality diesel fuel can disrupt combustion, causing uneven engine operation.

Overheating Engine

Cause: A failing water pump, clogged radiator, or low coolant levels can lead to overheating, which is especially concerning for diesel engines.

Check Engine Light

Cause: Issues such as EGR valve failure, a clogged diesel particulate filter (DPF), or sensor malfunctions can trigger the warning light.

Fuel Contamination

Cause: Water or dirt in the diesel fuel can lead to injector and fuel pump damage, causing performance issues and requiring system cleaning.

Turbocharger Failure

Cause: Excessive oil consumption, poor lubrication, or foreign object damage can cause a loss of boost pressure and reduced engine efficiency.

Unusual Engine Noises (Knocking or Hissing)

Cause: Injector knock, air leaks in the intake system, or exhaust manifold issues can produce unusual sounds during operation.

Excessive Vibrations

Cause: Faulty motor mounts, imbalanced drive shafts, or misaligned components can cause the truck to vibrate abnormally, especially at higher speeds.