Common Causes of Diesel Engine Failure

Written By JD Diagnostics & Diesel Repair on Oct 26, 2021

Diesel engine having service performed

It might go without saying, but those of us who love diesel love it a lot. With the days getting shorter and the trails getting muddier, it’s a great time of year for diesel 4x4 enthusiasts. Of course, that notoriously wet Southern BC weather and rugged outdoor conditions are a part of the challenge and the fun of 4x4ing! But, with that being said, nothing will ruin a weekend of off-road fun faster than a dead diesel engine. 

To that end, we’ve compiled a list of some of the most common causes of diesel engine failure. This should be old hat for the more experienced grease-monkeys, but it doesn’t hurt to have a reminder, and for newer enthusiasts, this should provide a good oversight into some things to look for before heading up Vedder Mountain or out to Stave Lake for the day!  

Most Common Cause: Water Contamination 

This is a good place to start considering the kind of weather and trail conditions you’re going to find around Abby. There are a couple of ways that water can get into your fuel system including condensation of water in the fuel tank and loose fuel caps.  

The problem with too much water contamination over a prolonged period of time is that it has the potential to oxidize the system from the inside. As the rusty metal flakes off into the fuel system, the pieces cause abrasion from within and compromise your seals, valves and filters.  

Other Kinds of Impurities

Defective seals, blown head gaskets, and cracked cylinder heads

Water isn’t the only foreign contaminant that can ruin a diesel engine. If an engine has defective seals, blown head gaskets or cracked cylinder heads – all of which constitute serious damage on their own, glycol can make its way from the coolant and into the engine. 


A very small amount of glycol will cause the soot to coagulate and create a dump-out situation. This leads to sludge, blockage of filters, constricted oil flow as well as deposits – all of which are symptomatic of a diesel engine that is on the fritz.  

A layer of soot is perfectly normal in a healthy, well-used diesel engine. It is a byproduct of the combustion process and short of having an engine cleaned, an even layer of soot is nothing to worry about and will be present in all diesel engines that have spent time running.

Irregular concentrations of soot

What is troublesome, and can be a sign of an issue in a diesel engine, is irregular concentrations of soot. This could mean it is time for an oil change or worse. When there is too much soot or even sludge around the rocker boxes, valve covers, oil pan or dead deck it can signal a problem.  

Checking the engine for soot deposits and oil runs is a good idea before taking your vehicle out on the road or up any trails. What you want to see is a nice even smattering or layer of soot – when you notice clean drips or runs that can indicate a problem and we would advise you to take it into your mechanic for a closer look. 

With a little due diligence and some key signals to be mindful of, you can have confidence that your diesel will perform as expected the next time you’re up Sylvester Road or by Harrison Lake!

Diesel Industry Articles

Tips and tricks to keep you rolling in style.

Top Maintenance Tips For Your Ford F-250 Pickup Truck
May 16, 2024

Top Maintenance Tips For Your Ford F-250 Pickup Truck

Keep your Ford F-250 running strong! Learn top maintenance tips like oil changes, tire care, brake checks, filter replacements, and fluid checks. JD Diagnostics & Diesel Repair in Abbotsford, BC keeps your F-250 reliable & ready for anything.

Read Post >
The Impact Of Lift Kits On Truck Performance And Handling
January 23, 2024

The Impact Of Lift Kits On Truck Performance And Handling

Explore the impact of lift kits on truck performance and handling at JD Diagnostics & Diesel Repair in Abbotsford, BC. Learn about the pros, cons, and considerations before opting for a lift kit. Make an informed decision for a truck that aligns with your needs and desires.

Read Post >
Semi truck's air intake system
June 16, 2023

The Benefits Of Upgrading Your Truck's Air Intake System

Upgrading your heavy-duty truck's air intake system can deliver various benefits, such as improved engine performance, fuel efficiency, and longevity. Discover different upgrades available and the technical advantages they offer in this blog.

Read Post >

Get In Touch

Give us a call below to speak with one of our service representatives.


Monday | 8a.m. – 4:30p.m.
Tuesday | 8a.m. – 4:30p.m.
Wednesday | 8a.m. – 4:30p.m.
Thursday | 8a.m. – 4:30p.m.
Friday | 8a.m. – 4:30p.m
Saturday | Closed
Sunday | Closed