There are a lot of komatsu pc150lc-6 hydraulic problems and solution operators face in the field. It is vital to understand these tips in order to be successful using this machinery.

komatsu pc150lc-6 Hydraulic pump problem

I am working on a pc150lc-6 Komatsu excavator. The hydraulic pump has been removed, cleaned, and replaced. It was found that the pump still leaked oil into the water. The oil is stored in a large tank behind the main fuel tank. The oil is pumped to the engine as it is needed. I think this is a good idea, because the oil that accumulates in the pump is internal leakage. There is no way to know exactly how much oil has leaked into these pumps without completely disassembling them. I don’t know if this system is used in other brands of excavators?

The solution: send the old pump back to Komatsu for repair and pay a lot of money (approximately $ 5,000). Or buy a new used pump for about half that price. This can be fine if there are not so many other problems with this machine or if this machine does not have high hours. Sometimes things are too good to be true!

komatsu pc150lc-6 Main relief valve problem

This is a common problem with a simple solution.

If your Komatsu PC150LC-6 excavator is needing more throttle to perform the same tasks as previously required, and it has been running at reduced power for several hours, even after you have stopped using the hydraulic controls and shut off the machine, you may have a stuck main relief valve.

It is not commonly known that your relief valve could be stuck in the open position. The relief valve is located in the center of your main control valve on top of your engine. In order to see if this is your problem, remove one of the hoses going into or out of the control valve, and with your thumb or finger, feel for any air that may be leaking past the seal of the main relief valve. If there is air leaking past the seal, this means that your main relief valve has failed and needs to be replaced. If it feels like a solid seal when you close it off with your thumb or finger, then you probably do not have this problem. If you do have this problem, don’t worry about it! It’s an easy fix!

komatsu pc150lc-6 Auxiliary relief valve problem

A Komatsu 150lc-6 excavator with the aux hydraulics not working. The owner was complaining that the machine was slow to respond when the auxiliary button was pressed.

The previous owner had installed a 150 degree thermostat around the oil cooler lines because he said the machine got hot. He also added a bypass valve for the oil cooler.

After talking with him and doing some research on this model of excavator I found that it gets hot normally and it is usually caused by a worn turbocharger. I looked in the radiator fins and they were clean and shiny. The previous owner had done a good job of keeping the radiator clean.

I tested the pressure relief valve on the right side of the hydraulic pump and it worked properly, so I removed it and installed it on my bench. I found that when I pushed down on the plunger, it leaked around the plunger and wouldn’t hold pressure past 200 psi.

Replacing this part fixed his excavator problems, but it wasn’t cheap, so if your Komatsu is like this one, then you need to keep an eye on it.

komatsu pc150lc-6 Pilot fluid pressure low

1. Pilot Pump Suction Filter is clogged

2. Pilot Pump Suction Pipe is bent or has a hole in it

3. Pilot Pump is defective or the internal valves are sticking

The pilot pump suction filter may get dirt in it, which can cause a restriction of flow to the pump. If there is not enough flow to the pilot pump, the pump will cavitate and cannot produce enough pressure to operate any of the controls. The pilot pump suction pipe is normally very flexible and is often routed through other piping. The pipe is sometimes located where it can be damaged by sharp edges. A damaged suction pipe will also cause a restriction of flow to the pilot pump, which can cause a loss of pressure. The pilot pump itself can have internal problems, such as dirt in the valve area, or a sticking valve. This will also reduce the amount of flow to the system and cause low pressure problems. If any of these conditions exist, repair or replace it.

komatsu pc150lc-6 Pilot fluid pressure high

1. Pilot fluid pressure high.

2. low engine oil pressure.

3. engine overheating and blowing coolant out of the overflow tank.

Upon arrival, I removed the left side access panel, main valve section and pilot pump section. There was evidence of a slow coolant leak on top of the pilot pump housing at the O-ring seal between the main valve section and pilot pump section. This O-ring is generally replaced during a 1,000 hour service but this machine only had 200 hours on it and had been serviced at 100 hours by another shop. I removed and replaced the O-ring and also replaced the pilot filter or suction strainer as we call them in heavy equipment repair.

I reinstalled everything and now had a very high pilot fluid pressure reading in the computer screen which showed 2,800 psi when it should have been around 900 psi. I then removed all 4 plugs from the main control valve manifold or simply called the “main control block”. There are 2 sizes of plugs for this job so be careful not to mix up these plugs. The lower plugs are large with a square head and 5/8″

komatsu pc150lc-6 Load sensing circuit malfunction

Detected at power up (initialization)

· The engine speed is less than 400 rpm.

· The engine speed is greater than 1,000 rpm.

Detected during operation

· The engine speed is less than 400 rpm.

· The engine speed is greater than 1,000 rpm.

· More than 10 seconds have passed since the hydraulic pump was started.

· The hydraulic pump pressure is more than 4,100 kPa (41 bar) or less than 200 kPa (2 bar) while the engine speed is more than 300 rpm.

· When the operating device controller detects a load sensing circuit failure, the engine speed drops to 0 when the inching pedal is released, and the travel direction cannot be changed by pressing the travel direction changing switch.

komatsu pc150lc-6 Cylinder malfunction

A customer close to my location came and asked if I could help her with her PC150lc-6 komatsu excavator.

The boom cylinder didn’t work properly and the customer wanted to know if I could repair the cylinder at their site, they had a workshop but they didn’t have the time and tools to do it themselves.

I went there and found that the seal on the end cap was damaged so I replaced that seal first.

I decided to do a complete service on this cylinder as well, to give it a new lease of life.

This Komatsu PC-150LC-6 excavator was made in Japan (before Komatsu bought out Poclain)

After I’ve done the service I tested the boom cylinder, everything worked fine except when in used full power it started leaking oil from under the boom.

So I checked the boom cylinder again for leaks and couldn’t find any leaks or damage anywhere.

After some research I found that this type of hydraulic cylinders can be very sensitive to dirt inside the hydraulic system.

komatsu pc150lc-6 Hydraulic motor malfunctionlinkage problem

Why was the hydraulic motor malfunctioning on this Komatsu PC150LC-6, and how did I fix it? It’s a real puzzler. I’ll show you all the steps I took to diagnose, fix and test the problem.

It had a hydraulic leak that turned out to be from the hydraulic motor. We fixed that, but then the linkage started binding up. We took out the linkage, greased it and put it back together and got it all functional. Then we had another problem with one of the hydraulic hoses to the motor where it was binding up. We replaced that hose, put everything back together again, and now everything is working fine.

This information will be applicable to you all the time when operating your komatsu pc150lc-6 and we hope that you will benefit from this content.