Buying a Secondhand Diesel?

Buying a Secondhand Diesel?

Carry out this diesel check before you do

Here are my 5 free guides on how to buy a used car

The popularity of diesels continues to rise. With falling fuel prices you can actually buy a litre of diesel for less than that of petrol. It hasn’t been like that for many years and car drivers have rarely had it so good.

Buying a diesel motor is great for two main reasons.

  1. You usually get better economy
  2. You can often resell the car easier when it’s a diesel

Clearly it’s going to depend on the car type in question, but diesel engine cars do tend to sell easier than petrol.

But there’s a car check that you need to carry out on a used diesel car before you buy it. It’s one that almost nobody knows about unless you’re a mechanic or have experienced the problem before.

diesel engine won't start image

The Cold Start – Warm Start Check

Does the car start exactly the same when it’s hot and cold?

This is very important because a diesel engine is completely different at varying temperatures. When a diesel engine warms up the components expand and the engine begins working in an entirely different way. But despite this…

A cold diesel engine should start within 2 seconds of turning the key

A hot diesel engine should start within 2 seconds of turning the key

Otherwise problems ensue.

If the car isn’t starting well when stone cold you should immediately walk away from the vehicle.

But, you may find a used diesel that doesn’t start very well when hot. So after you’ve gone for your test drive, switch off the engine, wait 30 seconds and restart the car. Does it immediately start?

Pay particular attention to German diesel engines, especially Volkswagens, Audi’s, and Skoda’s. Also, the Spanish manufacture SEAT’s are also known to have warm start problems.

If the car doesn’t start well when warm I would not buy it. There are a number of reasons why the car won’t start. These range from starter motor problems, worn glow plugs, dirty fuel filters and others.

Frustratingly, you can have a diagnostic from a specialist and still not find the fault. Often the error codes do not match the actual issue, but flag up some other engine component that’s not working optimally.

Whatever you decide to do just remember that it’s going to cost a fair bit of money to repair and replace. You may have to go through a process of elimination, until you find which part is causing the issue. Once you buy a new part and fit it to the car you can’t return it and get your money back. So workshops will generally start with the cheapest items, replace them and test the fault.

I remember owning a 2009 Skoda Octavia diesel. We spent over £700 trying to fix the issue. Eventually we found that the starter motor was at fault, but the diagnostic read glow plugs and fuel filter issues.

If you find yourself out on the road and your diesel car suddenly won’t start, try letting it cool off for half an hour before trying to restart the vehicle. It might just work!

Always be vigilant and remember that once you own a used car you are usually the one that’s liable.

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