Reasons Why Oil Leakage From New VTM42 Pump Shaft Seal

Some weeks ago, we received customer complaints that a brand-new unused VTM42 steering pump had oil leakage after installation, and the oil pressure could not be established normally. We requires the customer to send this VTM42 pump back to our technical department for quality cause analysis:

1, What we found after the VTM42 pump dismantling

After dismantling the faulty VTM42 pump, it was found that the reason of the oil leakage from the bearing was that the shaft seal near the bearing was washed out due to some kind of high pressure, and the damage of shaft seal is shown as follows:

2, Possible reason of the shaft seal damage

As we can see from the above picture, the shaft seal is washed out from the pump housing to the bearing side. The shaft seal is normally under low pressure, and the shaft seal is flushed out by some abnormal high-pressure air or oil.Our engineers thought that this area was the oil inlet, and there would be no high-pressure oil. The only possibility is high-pressure air.

The high-pressure air is mainly due to the presence of air in the oil inlet pipeline, and the air is compressed in a short time when the pump was started, and then the high-pressure air can only overflow from the shaft seal to relieve pressure. We can verify this from the state of the shaft oil seal turned out, to the bearing side!

3, Solution

The presence of air in the inlet line is a scary affair and can often cause unexpected, sometimes catastrophic damage to hydraulic pumps. As we all know, oil is incompressible, but air can. The sudden depressurization of compressed air in a low-pressure area usually results in an explosion, squeak or pressure instability.

So,when we install a new pump in a hydraulic system, it is important to drain all the air in the inlet line. The method is to tighten all the screws of the oil inlet, loosen the screws of the oil outlet, open the fuel tank valve, and then not tighten all the oil outlet screws until you see fresh oil coming out of the oil outlet. In this way, all the air in the inlet line is drained out.

We extend our customers one year warranty since export date. Want to buy high quality replacement Vickers VTM42 hydraulic pumps, contact Super Hydraulics to find the best solution for your hydraulic system!