The engine is the most expensive part of a car and probably the hardest to judge. A quick peek in the engine bay is interesting, but what can actually be seen here? Under the bonnet you can find clues that point to the weak and worn out parts of the engine. A weak part may require maintenance, but can also mean very expensive repairs, in which case it is advisable not to buy the car.

Because it is not possible, to write down every weak point from every car made in the last decade. You will find practical information, in this article, that you can use while judging an engine. Do not worry, you do not need an extensive technical education before you are able to do this. Though, it is most important that you use all your senses in addition to this information. You will have to look, feel and listen to the engine.

Under the bonnet

You can check under the bonnet for clues that point out weak parts of the engine. Look carefully at the joints that run horizontally through the engine. Between these joints are the so called "gaskets." These gaskets seal off the joints between the main engine parts. In the figure below you can see the main parts of the engine. The three gaskets from top to bottom are: valve cover gasket (nr.2), head gasket and crankcase gasket (which are both not shown).

When one of these gaskets is worn out, oil will leak through the joint. To prevent the loss of oil, the gasket has to be replaced. Especially the head gasket is expensive to replace, because this one is located in the middle section of the engine. Replacing it is a time consuming job and as always: time is money.