Buying a Used Engine

GENERAL INFORMATION

Be careful when buying a used diesel. Diesel engines run for a long time, but this does not mean you should not inspect all the traditionally worn areas. On some engines it is very easy to disguise both the length of service and the wear. When assessing the condition of such an engine there is a risk of being misled if you do not know diesels well.

As with gasoline engines, diesel exhaust should be smoke-free. In addition, smoke should not come out of the oil filler neck opening on a warm engine. Since diesel engines are noisier than gasoline engines, you must distinguish normal operating noise from knocking caused by worn pistons, connecting rods, camshaft, etc. If you have doubts about the condition of the engine, contact professionals for assistance.

Turbodiesels are very popular because turbocharging suits the characteristics of the diesel well. Turbochargers operate at low boost pressure and at low engine speeds, which gives them a longer service life than turbochargers on gasoline engines. Turbodiesels are ideally suited to tractors and multi-ton trucks.

However, diesel engines have difficulty meeting the demands of automatic transmissions because of the flat torque curve. Few manufacturers are concerned with this problem. Among them are Citroen, Mercedes, Peugeot and, more recently, Opel, but even they use automatic transmissions only in mid-size vehicles.

Due to their growing popularity, diesels are no longer regarded as the poor relation, and in terms of their finish they fully match their gasoline counterparts.

When buying, pay attention to the residual value of a diesel. Diesel vehicles once gave impetus to growth in vehicle sales in Germany, but the peak of sales was reached four years ago and since then there has been a gradual decline, so make sure you do not overpay for the privilege of owning a diesel vehicle.

Check the mileage. Diesel vehicles are bought for their potentially high reliability and possibly high mileage, especially when purchased new. But this does not mean you should not pay attention to the odometer. Indeed, many dealers do not like to deal with vehicles whose mileage exceeds 80,000 km and adjust the price accordingly, or simply roll back the odometer. A mileage of 160,000 km is quite natural for a well-maintained diesel engine, but think twice if the odometer shows 320,000 km or, especially, if it is a former taxi with such mileage.

Apart from the engine, most diesel vehicles are identical in design to their gasoline counterparts. The same applies to suspensions and brakes, but take parts prices into account. For example, exhaust systems last a long time but differ from those of gasoline engines. If you are used to buying parts from salvage yards, keep in mind that gasoline engine parts may look similar and fit in size. However, the diesel engine block differs from a gasoline engine block and in most cases cannot be used as a replacement. Transmission and clutch gear ratios also differ.