How To Change the Komatsu Hydraulic Filter (1000 Hour Service)

  • Written by Arsalan
Heavy duty mechanic at a construction site sitting on top of a large Komatsu excavator

If you’re working on Komatsu excavators, then you know the importance of keeping them in top condition through preventative maintenance. That’s why a 1000-hour service is necessary to keep your machine running smoothly and safely.

Part 1 of our 1000-hour Komatsu excavator service series explained how to drain the engine oil as well as replace the oil filter and fuel filter. Then in part 2, we completed changing the excavator engine oil and checking coolant levels.

In part 3, we’ll be focusing on how to change hydraulic filters – an essential part of your excavator maintenance routine. The Komatsu hydraulic filter location is on the top, so for this section of the 1000-hour service you’ll be on top of the excavator.

Prefer to see a video tutorial instead?

Change the Hydraulic Filter

Before working on the Komatsu hydraulic filter, make sure there isn’t any pressure in the hydraulic tank by loosening the tank cap. This will relieve any pressure in the tank.


Heavy equipment mechanic loosens the tank cap for the hydraulic system on a Komatsu PC200LC excavator

Now remove the bolts and open the hydraulic filter cover.


Arrow points to the Komatsu hydraulic filter location on top of the excavator

You’ll notice a large spring for the bypass which gets set on top of the filter. Take it out and set it aside.

Next, remove the bypass valve. This bypass is a crucial part of the hydraulic system. It’s designed to relieve any pressure build-up (which can cause premature wear or worse).


TIP: Remove the tank cap to make the hydraulic oil level drop faster so the bypass valve is easier to access.

Now remove the screen inside the bypass valve. The screen is a cylinder made up of two layers of mesh meant to catch smaller particles and prevent them from getting into the hydraulic pump.


Heavy equipment technician inspecting the bypass filter screen on top of an excavator

You’ll finally be able to change the hydraulic filter now. Take out the old hydraulic filter and place it in a bucket or pan to avoid spilling excess oil everywhere. Put the new Komatsu hydraulic filter in. It should be easy to tell if you’ve put it in correctly because it sits around a little tube/ spigot.

Insert the screen, bypass valve, and spring.

Before you finish we recommend you change the o-ring. Worn-out o-rings let the moisture in, and if water gets into your hydraulic oil it can degrade the oil and cause problems for your machine.


Arrow points to the hydraulic cover o-ring

With the change of the hydraulic filter complete, you can close up the filter cover. Tighten the bolts of the filter cover in a cross pattern. This will help it go down evenly and prevent deflection which can warp the plate. Now you can snug the bolts.

Don’t screw the tank cap back on just yet.

Change the Foam Breather Filter

On the tank cap is a little piece of foam for the vent. This is the foam breather filter.

Replace the old foam breather filter with a new one. Just make sure it doesn’t get twisted or stuck in the spring when you’re slipping it on.


Comparison of old versus new foam breather filters for the hydraulic tank cap

While the excavator is running, pressure builds up inside and air wants to come out. But as the machine cools, the air gets drawn in — along with any dust or debris. The foam breather filter prevents those particles from being drawn into the hydraulic tank.

Refill the Swing Gearbox Oil

The capacity of our Komatsu excavator is around 7.1 liters. We used a pail pump to pump 30-weight oil back into the swing gearbox.

Keep the dipstick out of the tube while you’re pumping oil. Allowing air in will minimize oil spillage as you pump.


Oil comes back up the tube as a heavy-duty mechanic demonstrates why you shouldn’t leave the oil dipstick in while pumping oil

The hydraulic oil must be filled up to the mark. Double-check the dipstick and make sure the oil is filled up to the required level.


HD mechanic Shawn showing the hydraulic oil dip stick level

End Notes

Regularly replacing your hydraulic filter and refilling the hydraulic oil at least once every 1000 hours is a must if you want to keep your excavator running properly. By keeping up with your regular service intervals and following our simple instructions, your Komatsu excavator will be running smoothly for years to come.

Next up we’ll tell you how to do a final drive oil change and replace the cabin air filter in part 4 of our 1000-hour Komatsu excavator service.

Visit the FortisHD blog for more tips, tutorials, and guides about heavy equipment

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