How To Test The Engine Of Used Construction Equipment Like Excavators Or Wheel Loaders

First of all, I want to say that most of the big used equipment suppliers are not crooks. But as the Germans say: “The exception proves the rule.” And what’s better than hoping an engine is good? It is 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 if the engine is cold. If it has already overheated, this may be a sign of cold engine starting (compression) problems.
• Check the condition of the oil. New oil along with old air and fuel 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 running water and the coolant should be more or less clear. It must not smell of diesel and must not contain oil.
• Keep the coolant reservoir open and start the engine. Look at the smoke at startup. 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 it’s 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 to the crankcase. Therefore, a vent line exists and is accessible with most engines. (With some modern engines, this hose goes back into the air intake channel to return gas to the engine.)

To check 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 you a feel: Blow through your nose into your hand. If the engine wear level is normal, it should be minor. The engine must idle! The oil filler cap must not be covered with gray residue. This would be a sign of engine oil leaking.

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

After running the engine for 20 minutes, you can take a look at it. Take a flashlight and look for leaks.

If you’re not sure you can perform these tests, don’t have time to travel, or just want to leave this job to the experts, call a company like MEVAS to have a machine inspected. The author of this article runs a used equipment appraisal company and has many years of experience inspecting equipment.