When to Replace Your Bobcat Hydraulic Filter

The hydraulic filter on a Bobcat removes contaminants from the hydraulic fluid before they can damage the pump, cylinders, and control valves. Bobcat's service manual recommends replacing the hydraulic filter every 500 hours of operation for most skid steers and compact track loaders. Warning signs of a clogged filter include slow hydraulic response, jerky bucket movements, and an unusual whining noise from the pump.

Key Points

• Replacement interval: Every 500 hours of operation (or sooner in dusty or high-debris environments)
• Warning signs: Sluggish hydraulic response, jerky movements, pump whine, overheating fluid
• Common part numbers: 6661248 (older models), 7012303 (M-series), varies by model
• Skill level: Easy to moderate (basic hand tools, 30-60 minutes)

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 hydraulic filter traps metal particles, dirt, rubber fragments, and other contaminants that circulate through the system during normal operation.

Without effective filtration, these 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
• Hydraulic motors: Drive motors lose torque as internal clearances increase from wear

According to Bobcat's maintenance documentation, the hydraulic system operates 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 have slightly different intervals depending on the model. Always verify the interval in your specific machine's operator manual.

Conditions that warrant more frequent changes:

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

From our experience serving equipment owners across North America, the most common mistake is stretching the hydraulic filter interval to match the engine oil filter schedule. The hydraulic system processes far more fluid volume per hour than the engine oil system, 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 in the filter media. 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: Hydraulic functions become inconsistent or jerky rather than smooth
3. Pump whine or cavitation noise: A high-pitched whine from the hydraulic pump area indicates the pump is struggling to pull fluid through a restricted filter
4. Overheating hydraulic fluid: Restricted flow causes the fluid to work harder, generating excess heat. Check the hydraulic temperature gauge if equipped
5. Bypass valve activation: Most Bobcat hydraulic filters have a bypass valve that opens when the filter is completely blocked, allowing unfiltered oil to circulate to protect the pump. At this point, the filter is providing zero protection

If you notice any of these symptoms, replace the hydraulic 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. Here is the progression of damage:

• Stage 1: Filter media saturates with contaminants. Flow restriction increases. Hydraulic functions slow down
• Stage 2: Bypass valve opens, allowing unfiltered oil to circulate. Contaminants reach all hydraulic components
• Stage 3: Accelerated wear on pump gears or pistons. Internal leakage increases, reducing system pressure and efficiency
• Stage 4: Pump failure. Replacement cost for a Bobcat hydraulic pump can exceed 10-20 times the cost of routine filter changes over the same period

A hydraulic pump failure often sends metal debris throughout the entire system, contaminating every hose, valve, cylinder, and motor. A full system flush and multiple component replacements may be required.

Where Is the Hydraulic Filter Located on a Bobcat?

On most Bobcat skid steer loaders and compact track loaders, the hydraulic filter is located inside the engine compartment, typically on the right side of the machine near the hydraulic reservoir. Access is through the rear engine compartment door or the side panels.

Common locations by machine type:

• Skid steers (S-series): Right side of engine compartment, mounted to the hydraulic reservoir or on a bracket nearby
• Compact track loaders (T-series): Similar location to skid steers, accessible through the rear door
• Mini excavators (E-series): Typically under a side access panel near the hydraulic tank. Location varies more on excavators than loaders

Your operator's manual includes a diagram showing the exact filter location for your model. Some Bobcat machines have both a suction filter (on the pump inlet) and a return line filter (on the line returning fluid to the reservoir).

What Are Common Bobcat Hydraulic Filter Part Numbers?

Bobcat uses different hydraulic filter specifications depending on the machine series, engine platform, and hydraulic system design. Here are some of the most commonly ordered hydraulic filter OEM numbers based on our catalog data:

OEM Part Number	Filter Type	Common Models
6661248	Return line filter	753, 763, 773, 863, 873 (older models)
7012303	Hydraulic filter	S550, S570, S590, T550, T590
7253841	Hydraulic filter	S650, S770, T650, T770, T870
6692337	Suction strainer	Multiple skid steer and CTL models

These numbers represent common references. Your specific model and serial number determine the exact filter required. Browse our Bobcat parts collection 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 30-60 minutes depending on filter accessibility.

1. Prepare the machine: Lower all attachments to the ground. Shut off the engine and allow the hydraulic fluid to cool. Relieve residual hydraulic pressure by cycling the control levers several times with the engine off
2. Access the filter: Open the rear door or side panels to reach the hydraulic filter housing
3. Place a drain pan: Position a drain pan under the filter to catch any fluid that spills during removal
4. Remove the old filter: For spin-on filters, use a filter wrench to unscrew it. For cartridge-style filters, remove the housing cap and pull out the element
5. Clean the mounting surface: Wipe the filter base or housing interior clean. Remove any old gasket material
6. Install the new filter: Apply a thin film of clean hydraulic fluid to the new filter's gasket. Thread on by hand until the gasket contacts the base, then tighten an additional 3/4 to 1 turn by hand. Do not overtighten
7. Check the fluid level: Top off the hydraulic reservoir to the correct level with the specified hydraulic fluid
8. Start and test: Start the engine and cycle all hydraulic functions slowly several times. Check for leaks around the new filter. Recheck the fluid 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 components. Consult a certified mechanic if you are unfamiliar with hydraulic system service.

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. The same filtration standards apply regardless of the brand name on the canister.

When selecting an aftermarket hydraulic filter, verify that it matches these specifications from the OEM:

• Micron rating (typically 10-25 microns depending on filter position)
• Flow capacity rated for your machine's hydraulic 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 aftermarket hydraulic filters cross-referenced to OEM numbers for easy identification.

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 reservoir)	Return line (before fluid enters reservoir)
Purpose	Protects pump from large debris	Catches fine particles from system wear
Micron rating	Coarser (100-150 microns typical)	Finer (10-25 microns typical)
Replacement frequency	Less frequent (often cleaned rather than replaced)	Every 500 hours (standard service item)

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

How Do I Dispose of Used Hydraulic Filters Properly?

Used hydraulic filters contain contaminated oil that should not enter the waste stream. Proper disposal involves:

• Drain the filter: Puncture or invert the filter 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 auto parts stores and recycling centers accept used oil filters. Check your local regulations for specific requirements
• Never dispose in regular trash: Hydraulic oil is a regulated waste in most jurisdictions

Frequently Asked Questions

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

Cross-reference your OEM part number (found on your 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 completely clogged filter forces the bypass valve open, sending unfiltered oil through the pump. Contaminants score internal pump surfaces and accelerate wear. Pump replacement costs significantly more than routine filter changes.

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

Not every time. Bobcat's maintenance schedule typically calls for hydraulic fluid changes every 1,000-2,000 hours, while filter changes are every 500 hours. However, if the fluid appears dark, 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 100-150 microns. The correct rating depends on your specific model's hydraulic system design. Use a filter that matches the OEM specification.

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. Even within the same equipment type, different model generations may use different filters. Always verify by serial number.

How much does a Bobcat hydraulic filter replacement cost?

Aftermarket hydraulic filters typically cost 20-60% less than dealer-sourced OEM filters. The exact price varies by model and filter type. The real cost savings come from preventing pump damage: routine filter changes protect components that cost many times more to replace.

Can I clean and reuse a hydraulic filter?

Spin-on hydraulic filters and disposable cartridge elements should not be cleaned and reused. The filter media traps contaminants internally, and cleaning does not restore full filtration capacity. Suction strainers (wire mesh screens) can be cleaned and reused per the manufacturer's instructions.

What type of hydraulic fluid does my Bobcat use?

Most Bobcat machines use a 10W hydraulic fluid meeting the specifications listed in the operator's manual. Using the wrong viscosity can affect filter performance and system operation. Check your manual for the specific fluid specification and capacity.