Are You In The Market For A Used Diesel? Read This First!

Trying to purchase a used diesel can be a daunting task even after you’ve narrowed down the ideal truck. Shopping at dealerships can be tiresome due to the pushy sales tactics while private party sales have their own challenges.

No matter where or who you end up purchasing from there are some important steps that should be taken to limit the chances of walking into a money pit that someone else may have walked away from. All used vehicles are being sold for a reason and fall into one of three categories: must be sold due to financial reasons, the owner truly wants something new or different, or it has been nothing but problems.


Used trucks can be a sea of bad news. If the vehicle is gone through properly beforehand it can end up being a score.

Working at a diesel repair shop you can see a lot of impressive things and unfortunately a lot of the opposite. The opposite for some is telling a customer that the truck he or she just purchased needs a laundry list of repairs and maintenance which quickly turns the excitement of a new vehicle to frustration and sometimes anger. Here are some tips to help keep you out of that situation.

Seeing this after popping the cap on the radiator could mean there is more to the truck than meets the eyes.

A visual inspection would normally be the first step  in a purchase and you’ll want to make sure the interior and exterior are up to your approval. Once that need is met you’ll want to take it for a test drive.

Before taking it out on the streets and getting everything up to operating temperature you should have a mental checklist to view on the truck. That list should include the basics like fluid condition and levels, inspection of battery cables, are there any leaks present, are all of the lights operational, running the heater and air conditioning, and looking for uneven wear on the tires.

Knowing what some parts are and how they work will make this process a lot easier.

Lastly, find out if all of the emission components are in place. If they have been removed make sure the owner still has them, especially if the truck requires a catalytic converter and diesel particulate filter which can cost a few thousand dollars to replace. Taking just a few minutes here can uncover a lot about a vehicle, sometimes it could be something the owner isn’t even aware of.

This is highly unsafe!

The next step is to drive it to see how it performs, right? Nope, not yet. If possible try to look at a vehicle early in the morning, or at least see how warm the engine is before you start it up. Diesel engines can be difficult to start when cold or not warmed up if there are problems within the fuel injection system, glow plug circuit, or further in the bottom end to name a few.

Hopefully, the engine does not have an uneven crank, does not smoke once started, and does not idle rough. Any of these symptoms could lead to costly repairs. At this point, you can now take it out for a spin. Pay close attention to the tailpipe looking for signs of smoke.

Ideally, there should not be any unless it has larger than stock injectors or high-performance tuning in which case you may see some black smoke on heavy acceleration. While driving it you’ll want to make sure it reaches operating temperature, the transmission does not slip or slam into gear, and of course make sure there are no unusual noises or vibrations. At this point, you’ll probably have a good idea whether or not the truck should soon reside at your home.

Practicing an oil pan reseal, three times!

The last step to take can be inconvenient and will likely have you paying out of pocket before you even own the truck, but can be worth every penny. Look online for a specialized diesel shop close to you or at least close to where the truck is located.

Contact a repair shop or even a dealership to see if they offer a pre-purchase inspection. Most shops will and they don’t take long to complete and for a small fee it can help determine if it’s worth buying or time to keep looking.

A technician familiar with diesel trucks should easily be able to spot common failures that are seen (at least externally), scan and check for any trouble codes that may not be setting a check engine light, and monitor select components of different operating systems. If a truck has problems that you couldn’t spot the technician may see things that could have your credit card maxed out pretty quick.

Bent and cracked lower control arm may have been missed, but a technician will be sure to spot it.

There are plenty of used trucks out there for sale that have been well maintained and not abused which have a lot of life left in them. We have seen several times where a dealer or owner will have repairs performed in good faith for the sale which shows there are good people out there.

On the other hand, We’ve seen some very questionable things over the years from flat out lies about previous repairs performed, repairs so poorly done it makes you use both hands when you scratch your head, and safety items flat out ignored. Don’t let this article scare you away from buying a used diesel, but rather help you be more informed when that time comes. Good luck on the hunt!

About the author

Gary Maschner

Gary Maschner's automotive passion started at a young age and grew over time. Working in a diesel shop, he continually expands his knowledge and wisdom of diesel repair and performance. Gary enjoys driving his heavily modified Duramax, and spending time with family rolling over rocks in his Cherokee XJ through the Arizona backcountry .
Read My Articles

Rolling coal in your inbox.

Build your own custom newsletter with the content you love from Diesel Army, directly to your inbox, absolutely FREE!

Free WordPress Themes

We will safeguard your e-mail and only send content you request.