Where Is the Hydraulic Filter on a Bobcat? All Locations

The main hydraulic filter on most Bobcat skid steer and compact track loaders sits in the rear engine compartment, reached through the tailgate. Many machines also carry a second filter that owners miss: M-Series loaders hide a hydraulic charge filter under the cab, and several models add case drain filters. Locations by model are below.

Key Points

• Main filter location: Rear engine compartment on most loaders, behind the seat with the cab raised on older K-Series machines
• The one people miss: M-Series loaders have a separate charge filter under the cab; several models carry case drain filters too
• Replacement interval: Every 500 hours of operation, sooner in dusty or high-debris work
• Part numbers: Vary by series and serial number. Common references include 6661248, 6692337, 6686926, and 7024037

Where Is the Hydraulic Filter on a Bobcat?

On most current and recent Bobcat loaders, the main hydraulic fluid filter is in the rear engine compartment. Open the tailgate and look near the hydraulic reservoir, usually on the right side of the machine.

On M-Series loaders there is a second filter in a place many owners never look: the hydraulic charge filter mounts under the operator cab. Reaching it means tilting the cab forward, which is a normal service procedure. Remove the two nuts at the front corners of the cab, lift with the handrails until the cab locks upright, and the filter is in front of you. Bobcat publishes separate service videos for the fluid filter and the charge filter on these machines because they are two different jobs.

On older K-Series and G-Series machines such as the S185, S250, and S300, the main spin-on filter is behind the seat area and is reached with the cab raised. Mini excavators keep the filter under a side access panel near the hydraulic tank, and the position varies more between excavator models than it does on loaders.

Which Filter Location Applies to My Model?

These are the models owners ask about most, with the locations that apply to most machines in each series. Production changes happen within a series, so confirm against your serial number before ordering.

Model	Main hydraulic filter	Also check
S650, T650	Rear engine compartment	Charge filter under the cab (tilt cab forward)
T770, T870	Rear engine compartment	Charge filter under the cab (tilt cab forward)
S550, S570, S590, T550, T590	Rear engine compartment	Charge filter under the cab (tilt cab forward)
T66 and other R2-Series	Rear engine compartment	Case drain filter serving the drive motors
S300, S250	Spin-on behind the seat, cab raised	Two case drain assemblies: one under the seat area, one behind the left rear panel
S185 and similar K-Series	Behind the seat area, cab raised	Case drain filters in the drive circuit
T190, T300	Engine compartment area	Case drain filters in the drive circuit
Legacy 700-Series (743 to 773, 863)	Engine compartment	Case drain filter element on many machines

Why Does My Bobcat Have More Than One Hydraulic Filter?

This is the detail that causes the most trouble. A Bobcat can carry two, three, or more hydraulic filters depending on the series, and servicing only the obvious one in the tailgate leaves the rest in place well past their capacity.

• Main fluid filter: The primary return filter near the reservoir. This is the one most people find and change
• Charge filter: On M-Series machines, a separate filter under the cab protects the hydrostatic charge circuit that drives the machine
• Case drain filters: Many track loaders and some skid steers filter the drive motor case drain lines. The S300 carries two separate case drain assemblies in two different locations
• Suction strainer: A coarse screen at the pump inlet, cleaned rather than replaced on most machines

If your machine drives weakly on one side, or a drive motor has failed before, the case drain filters deserve attention. A plugged case drain filter raises pressure inside the drive motor case, and the motor shaft seal is usually what gives way first.

What Does the Hydraulic Filter Do on a Bobcat?

The hydraulic system is the muscle behind every Bobcat function: lifting, tilting, driving, and auxiliary attachments all run on pressurized hydraulic fluid. The filter traps metal particles, dirt, rubber fragments, and other contaminants that circulate through the system during normal operation.

Without effective filtration, contaminants cause accelerated wear on precision components:

• Hydraulic pump: Internal gear or piston surfaces score and lose efficiency
• Control valves: Contaminants cause spool valves to stick or leak internally
• Cylinders: Particles scratch cylinder walls and damage rod seals, leading to external leaks
• Drive motors: Motors lose torque as internal clearances increase from wear

Bobcat hydraulic systems operate at pressures exceeding 3,000 PSI. At those pressures, even microscopic particles act like sandpaper against precision-machined surfaces.

How Often Should I Replace My Bobcat Hydraulic Filter?

Bobcat recommends hydraulic filter replacement every 500 hours of operation for most skid steer loaders and compact track loaders. Mini excavators may differ by model. Always verify the interval in your machine's operator manual, and remember the interval applies to every hydraulic filter on the machine, not just the one in the tailgate.

Conditions that warrant more frequent changes:

• Demolition and concrete breaking: High shock loads generate more metal wear particles
• Dusty environments: Fine dust infiltrates the reservoir through the breather cap
• New machine break-in: The first 100 to 250 hours produce elevated wear particles as new components seat in
• After a hydraulic repair: Any time a line, cylinder, or pump is opened, change the filter afterward to catch debris introduced during the repair

The most common mistake we see is stretching the hydraulic filter interval to match the engine oil schedule. The hydraulic system processes far more fluid volume per hour, and its filter reaches capacity faster.

What Are the Warning Signs of a Clogged Hydraulic Filter?

A hydraulic filter does not fail suddenly. It gradually loses capacity as contaminants accumulate. Watch for these progressive symptoms:

1. Slow hydraulic response: The bucket, boom, or arms move noticeably slower than normal, especially when cold
2. Jerky or uneven movements: Functions become inconsistent rather than smooth
3. Pump whine or cavitation noise: A high-pitched whine from the pump area means the pump is struggling to pull fluid through a restriction
4. Overheating hydraulic fluid: Restricted flow makes the fluid work harder and run hot
5. Bypass valve activation: When the filter is fully blocked, its bypass valve opens and unfiltered oil circulates. The filter is then providing zero protection

If you notice any of these symptoms, replace the filter immediately rather than waiting for the next scheduled interval.

What Happens If I Don't Change the Hydraulic Filter?

Neglecting hydraulic filter changes is one of the most expensive maintenance shortcuts on any Bobcat. The filter saturates, the bypass opens, contaminants reach every component, and wear accelerates from there. The end state is a pump failure that sends metal debris through every hose, valve, cylinder, and motor on the machine, and a full system flush with multiple component replacements to put right.

What Are Common Bobcat Hydraulic Filter Part Numbers?

Bobcat uses different filter specifications depending on the machine series, engine platform, and hydraulic system design. These are commonly ordered OEM references from our catalog, matched to the model groups they serve:

OEM Part Number	Filter Type	Common Models
6661248	Hydraulic oil filter	Legacy loaders and K-Series including S185, S300, T190, T300
6692337	Hydraulic oil filter	A300, A770, S150 through S300, and related models
6686926	Hydraulic filter	M-Series including S650, T650, T770, T870
7024037	Hydraulic filter	S450 through S590, T450 through T590
6661807	Case drain filter element	Legacy 700-Series, 863, S300, T190, T300 group
7334208	Case drain filter	R2-Series including S66, S76, T66, T76

These numbers represent common references, and your serial number determines the exact filter required. Browse our hydraulic filters collection or the full Bobcat parts catalog and search by OEM number to find the right replacement.

How Do I Replace the Hydraulic Filter Step by Step?

Hydraulic filter replacement is a straightforward maintenance task. Allow 30 to 60 minutes depending on filter accessibility.

1. Prepare the machine: Lower all attachments to the ground. Shut off the engine and let the fluid cool. Relieve residual pressure by cycling the control levers several times with the engine off
2. Access the filter: Open the rear door or side panels, or tilt the cab for a charge filter
3. Place a drain pan: Position it under the filter to catch spillage
4. Remove the old filter: Use a filter wrench for spin-on filters. For cartridge styles, remove the housing cap and pull the element
5. Clean the mounting surface: Wipe the base or housing clean and remove any old gasket material
6. Check the O-rings and seals: Cartridge housings seal with O-rings that take a set over time. Replace them with the filter rather than reusing them, because a hardened O-ring is why a fresh filter starts weeping a week later. Our O-rings collection covers the common housing sizes by OEM number
7. Install the new filter: Apply a thin film of clean hydraulic fluid to the gasket. Thread on by hand until the gasket contacts the base, then tighten three quarters to one full turn by hand. Do not overtighten, because overtightening is what makes the next removal a fight
8. Check the fluid level: Top off the reservoir with the specified fluid
9. Start and test: Cycle all functions slowly, check for leaks, and recheck the level after the system circulates

Safety warning: Hydraulic fluid under pressure can penetrate skin and cause serious injury. Always relieve system pressure and allow the fluid to cool before removing any hydraulic component. Consult a certified mechanic if you are unfamiliar with hydraulic service.

How Do I Remove a Stuck Hydraulic Filter Canister?

Seized filter canisters are common enough on these machines that the removal question ranks alongside the location question. The filter was overtightened at the last change, or the gasket was fitted dry and has vulcanized to the base after hundreds of heat cycles.

Work up through these methods in order:

• Strap wrench: The first tool to reach for. A strap keeps gripping as the canister crushes, where a band-style wrench slips once the shell deforms
• Six point socket on the end nut: Where the canister has a hex, use a six point impact socket, starting gently and working up
• Last resort: Some owners resort to driving the canister around with a hammer and chisel against the shell. It works, but it deforms the shell, risks damaging the base threads, and fills the area with debris right where you are about to expose an open hydraulic port. Cover the port immediately once the filter is off

Prevention costs nothing: oil the gasket, tighten by hand only, and the next change takes two minutes.

What If the Hydraulic Fluid Looks Milky?

Milky or cloudy fluid means water has emulsified into the oil, usually through condensation, a failed cap seal, or pressure washing around the breather. A filter change alone will not fix it, because the filter cannot remove emulsified water. The fluid needs to be changed, and owners who have dealt with it report it often takes more than one fluid and filter change before the system runs clean. If you find milky fluid, plan for fluid, filters, and a check of how the water got in.

What Is the Difference Between Suction and Return Line Filters?

Most Bobcat hydraulic systems use filters in two positions, each serving a different purpose:

Feature	Suction Filter (Strainer)	Return Line Filter
Location	Pump inlet, inside or near the reservoir	Return line, before fluid enters the reservoir
Purpose	Protects the pump from large debris	Catches fine particles from system wear
Micron rating	Coarser, 100 to 150 microns typical	Finer, 10 to 25 microns typical
Replacement frequency	Often cleaned rather than replaced	Every 500 hours as a standard service item

The return line filter is the primary serviceable filter in most Bobcat maintenance schedules. The suction strainer is usually a reusable screen cleaned during major service or fluid changes.

Can I Use an Aftermarket Hydraulic Filter on My Bobcat?

Yes. Aftermarket hydraulic filters are manufactured to meet or exceed OEM filtration specifications, including micron rating, flow capacity, bypass valve pressure, and media quality.

When selecting an aftermarket filter, verify it matches the OEM on these points:

• Micron rating, typically 10 to 25 microns depending on filter position
• Flow capacity rated for your machine's pump output
• Bypass valve cracking pressure
• Physical dimensions: thread size, gasket OD, height

Our Bobcat skid steer parts and Bobcat compact track loader parts collections include hydraulic filters cross-referenced to OEM numbers.

How Do I Dispose of Used Hydraulic Filters Properly?

• Drain the filter: Puncture or invert it and let it drain into a collection container for at least 12 hours
• Collect the oil: Add the drained oil to your used oil recycling container
• Recycle the filter: Many parts stores and recycling centers accept used filters. Check local regulations
• Never dispose in regular trash: Hydraulic oil is a regulated waste in most jurisdictions

Frequently Asked Questions

Why does my Bobcat have two hydraulic filters?

Many Bobcat machines filter more than one circuit. M-Series loaders pair the main fluid filter in the engine compartment with a charge filter under the cab, and several models add case drain filters on the drive motor lines. Each has its own part number and its own service point.

Where is the case drain filter on a Bobcat?

It varies by series. On the S300 there are two assemblies, one under the seat area and one behind the left rear panel. On R2-Series machines like the T66 the case drain filter serves the drive motors. Your parts diagram shows the exact position for your serial number.

How do I know which hydraulic filter fits my specific Bobcat model?

Cross-reference your OEM part number, found on the current filter or in the operator's manual, with aftermarket equivalents. Your serial number confirms the exact specification. Contact sales@partsonline.com with your model and serial number if you need help.

Can a bad hydraulic filter damage my Bobcat's hydraulic pump?

Yes. A fully clogged filter forces the bypass valve open, sending unfiltered oil through the pump. Contaminants score internal surfaces and accelerate wear. Pump replacement costs far more than routine filter changes.

Should I change the hydraulic fluid when I replace the filter?

Not every time. Bobcat schedules typically call for fluid changes every 1,000 to 2,000 hours against filter changes every 500. If the fluid appears dark, milky, smells burned, or contains visible particles, change it regardless of the hour count.

What micron rating should my Bobcat hydraulic filter have?

Return line filters typically range from 10 to 25 microns. Suction strainers use coarser ratings of 100 to 150 microns. Use a filter that matches the OEM specification for its position.

Are Bobcat hydraulic filters the same across skid steers and excavators?

No. Skid steers, compact track loaders, and mini excavators use different hydraulic systems with different filter specifications, and generations differ within each type. Always verify by serial number.

Can I clean and reuse a hydraulic filter?

Spin-on filters and disposable cartridge elements should not be reused, because the media traps contaminants internally and cleaning does not restore capacity. Suction strainers are wire mesh screens and can be cleaned per the manufacturer's instructions.

What type of hydraulic fluid does my Bobcat use?

Most Bobcat machines use a 10W hydraulic fluid meeting the specification in the operator's manual. The wrong viscosity affects filter performance and system operation, so check the manual for the fluid specification and capacity.