Here’s a quick heads up from the team at Wrong Fuel Emergency with regards to a few cases that we have attended recently that we thought were worth mentioning. They concern motorists who have called us for assistance after having bought cars second hand from traders or privately via auto trade publications. We received a call from a mechanic associate of ours who was having trouble diagnosing a fault with a VW Golf that had been brought to him by a client. The Golf was running noisily under acceleration and was more difficult to start when warm, than from cold. These symptoms started alarm bells ringing with one of our expert engineers who had seen similar symptoms many times with a variety of vehicles, all of which had been running for some time with the wrong fuel in the tank. The vehicle owners in these cases, had filled up their vehicles with an amount of the wrong fuel and had then been informed that it would be fine to just top up with the correct fuel and run their vehicles until the contaminated fuel had all been used up. This is a common but very bad piece of advice and one that many motorists give or follow through lack of knowledge of modern vehicle fuel systems.
Our mechanic associate asked for the Wrong Fuel Emergency team’s advice on the best way to solve the problem with the VW Golf. We suggested in the first instance that a complete fuel drain and fuel system flush should be carried out. We also suggested that the fuel filter should be replaced as this is a simple and cheap job for a good mechanic to perform on a diesel VW Golf. In this particular instance, the car was OK following these steps and despite its wrong fuel trauma it started and ran fine when cold or warm. We think the new owner may have had a lucky escape.
The second case we encountered was a similar scenario but the vehicle in question was a nearly new BMW 420 diesel. The symptoms with this vehicle were similar but far worse than the Golf. Our engineer thought the car had probably been running with a far greater quantity of petrol in the tank. The fuel drain and flush carried out helped a little but our mechanic friend ended up having to replace the fuel filter, fuel pump and diesel injectors to get the vehicle running properly. As you may imagine, with a premium motor like a BMW, the repair cost ran into thousands of pounds and the motorist concerned was not particularly pleased at having been sold a nearly new car with this problem. The car was purchased from a dealer who attempted to refute the claims until our expert stepped in and helped the motorist get his money back.
The long and the short of it is, when buying a second hand diesel car, ask about the history and whether it has ever had the wrong fuel put into it. Also, make sure you get to start and run the car from warm as well as a cold start. If the car displays either of the symptoms referred to above, the noisy acceleration or the increased difficulty in starting when warm, then leave it well alone or at least ask for an expert opinion and bear in mind potential repair costs.