How to test the engine of used construction equipment such as excavators or wheel loaders

First of all, I want to say that most of the big used equipment suppliers are not thieves. But as the Germans say: “The Exception confirms the Rule.” And what is better than waiting for a good engine? Better to know.

When you arrive on site and go to inspect a used wheel loader, excavator, bulldozer, or any other construction machine with a combustion engine, we recommend the following procedure:

• Before turning the key, check to see if the engine is cold. If it is already warm, this may be a sign of starting problems with a cold engine (compression).
• Check the condition of the oil. New oil along with old fuel and air filters and no other service performed is a bad sign.
• Now open the cooler reservoir and look at the quality of the coolant. There should be no pure water and the coolant should be more or less clear. It should not smell like diesel and should not contain oil.
• Keep the cooler reservoir open and start the engine. Look at the smoke when starting. Some gray or black smoke should disappear after max. 30 seconds.
• Look inside the cooler reservoir or put your hand in the opening. There should be no pressure. Now you can close it.

Now is the time to check the so-called Blow-By. When an engine is running, a certain amount of pressure from combustion bypasses the pistons and piston rings and finds its way into the crankcase. Therefore, there is a vent line and it is accessible with most engines. (With some modern engines, this hose returns to the air inlet channel to return gas to the engine.)

To check the Blow-By, open the oil filler cap and place your hand. It is difficult to describe the level of Blow-By allowed. However, to give yourself a feeling: Blow your hand through your nose. If the level of engine wear is normal, it should be less. The engine must idle! The oil filler cap should not be covered with gray debris. This would be a sign that you are spilling the engine oil.

You can now perform other tests on the machine, such as a lockout test or a cycle time test. This will warm the engine to operating temperature. Run the engine at operating speed and observe the smoke. Some black smoke is normal under load. More black smoke is produced when the fuel is not completely burned. Blue smoke indicates that fuel is mixing with oil somewhere before burning. Unburned fuel entering the exhaust stream is responsible for white smoke.

After running the engine for 20 minutes, you can watch it again. Take a flash light and watch for leaks.

If you are unsure whether you can perform these tests, do not have time to travel, or simply want to hand this job over to the experts, call a company like MEVAS to have a machine inspected. The author of this article runs a used equipment appraisal business and has many years of equipment inspection experience.