CAT 314E Engine Oil Change & Other Routine Maintenance Tasks – Part 2

Written by Luis Montes Updated On  April 30, 2025

In the first part of this step-by-step guide series, we changed the engine oil and filter on a CAT 314E.

Part 2 will cover how to check and replace several hydraulic filters, including the suction screen, return, pilot, and case drain filters.

On the Tekamo HD YouTube channel, you can watch an expert heavy equipment mechanic demonstrate the process.

If you don’t have the time to perform the service yourself or want to enroll in a preventative maintenance program for your heavy equipment, contact Tekamo HD to schedule a heavy-duty mechanic.

Change the Hydraulic Oil Return Filter

Positive pressure will build up inside the tank, mainly due to the temperature. So, the first thing to do is vent the hydraulic tank. Otherwise, when you undo the filter, excessive oil will spill out.

To reach the fill cap and hydraulic tank lids, you must remove a cover from the top of the machine. Not all makes and models have a top cover. For example, the Komatsu PC200LC Excavator has no cover, whereas the John Deere 17G has a side and a top cover.

Remove the fill cap to vent the hydraulic tank.

Before doing the main filter, Keith checked the suction screen. It’s a metal screen that protects the pump from large contaminants. Take it out and look for debris. If so, clean it off before reinstalling it.

Set the suction screen on the bottom pipe of the tank (since it’s below the oil level, you’ll have to feel for it) and push it slightly to reattach.

Put the cap back on, ensuring that the cap nipple aligns with the top of the suction screen rod. It will align the rod and keep the suction screen in place. Almost all makes and models share the same design.

Let’s move on to the hydraulic return filter.

Remove the bolts from the hydraulic return filter cover. You’ll find a lid with a handle and a snap ring that holds it in place. Most CAT models have that design. A spring holds the return filter on machines like the John Deere 85G and the Komatsu PC200LC.

Remove the snap ring and pull the filter out.

Have a bucket or a drain pan at hand to put the filter in, as it will drip a lot of oil.

Don’t worry if the filter you’re installing isn’t exactly like the old one. It’ll be fine as long as the lengths and diameters match. In our case, we had to take the handle from the old filter to the new one.

The return filter design varies from one brand to another. Hitachi and John Deere have a built-in handle on their filters. Others, like the Komatsu PC200LC hydraulic filter, don’t have a handle.

Slide the new filter into the canister. There’s a small pipe at the bottom of the tank, similar to the suction screen. Wiggle and turn the filter to make sure it sits all the way down.

The handle slots into the cap, so when you put the handle back, ensure it aligns correctly with the bolt holes. Reinstall the snap ring and bolt down the return filter and suction screen lids.

Start tightening the bolts by hand and finish in a cross pattern with the tool of your preference. The cross pattern evenly distributes the tightening force to the lids, especially the one for the suction screen, which is spring-loaded.

Finish by reinstalling the fill cap and the top cover.

The Ko-ken sockets have one of the shallowest profiles in the industry without compromising strength.

Visit Fortis HD to purchase from a wide array of Ko-ken products, including chrome, impact, and bit sockets.

Change the Pilot and Case Drain Filters

Not all makes and models have a case drain filter. The CAT 314E excavator has a pilot and case drain filters. Both are in the right-side compartment.

Before removing the filters, place a drain pan underneath to catch the oil that comes out as you loosen them. Since we previously vented the tank, a small drain pan will be enough. Turn the filters clockwise to loosen them.

There are different pliers you can use to pull the filters out. In this case, we used a strap wrench and a ratchet.

The Mueller-Kueps Universal Strap Wrench is perfect for oil filters and dehydrator cartridges with a maximum diameter of 7 inches (180 mm).

Available at Fortis HD!

If you plan on using aftermarket filters, as we did, double-check the lengths, seal diameter, and threads against the OEM specifications to ensure they are compatible and safe to use. Also, ensure the old seals are not left in the housing (as it happened to us). Otherwise, you’ll have problems due to the double gasket.

Before installing the new filters, lube the seals with a thin oil film (you can use some of the old oil) to help the rubber slide instead of binding as you tighten the filters.

Hand-tightening the filters is more than enough. As mentioned in the previous post, we don’t recommend using tools to tighten spin-on fitters. In our article “Why You Should Not Use A Tool To Tighten Up A Spin On Oil Filter,” Keith explains the reasons.

Next Up

Our next post will cover how to adjust the track tension properly on the CAT 314E excavator.