A Bobcat T650 tilt cylinder seal kit includes all the hydraulic seals, O-rings, and backup rings needed to rebuild the tilt (bucket) cylinder on your compact track loader. If your T650 is leaking hydraulic fluid at the cylinder rod, drifting under load, or losing bucket hold, a seal kit is the fix and is far more cost-effective than replacing the entire cylinder. This guide covers what is included in the kit, how to verify fitment for your serial number, and how to replace the seals yourself.
TL;DR - Quick Facts
- What it does: Restores hydraulic pressure in the tilt cylinder by replacing worn internal and external seals
- Signs of failure: Hydraulic oil leaking at the cylinder rod, bucket drift, sluggish tilt response
- Replacement part: Verify OEM cross-reference using your serial number. Seal kits vary by production run
- Difficulty: Moderate. Requires basic hydraulic knowledge and standard shop tools
- Installation time required: 2-4 hours depending on cylinder accessibility and experience
What Does the Tilt Cylinder Seal Kit Do on a Bobcat T650?
The tilt cylinder on a Bobcat T650 controls the bucket curl, tilting the bucket forward to dump material and back to scoop. The seal kit contains all the seals and O-rings inside the cylinder that keep hydraulic oil pressurized and prevent leaks. These seals create a barrier between the high-pressure and low-pressure sides of the piston, allowing the cylinder to extend and retract with force.
- Piston seals: Maintain pressure on both sides of the piston inside the cylinder bore
- Rod seals: Prevent external leakage where the cylinder rod exits the housing
- Wiper seals (dust seals): Keep dirt and debris from entering the cylinder
- O-rings and backup rings: Provide secondary sealing at connection points
When any of these seals wear out, the cylinder loses its ability to hold pressure, which directly impacts bucket control and machine productivity.
How Do I Know If My T650 Tilt Cylinder Seals Are Failing?
Seal failure usually develops gradually, giving you time to plan a repair before it becomes a major issue. Here are the symptoms to watch for:
- Visible oil leaks. Hydraulic fluid weeping or dripping around the rod end of the tilt cylinder is the clearest sign of rod seal failure.
- Bucket drift. The bucket slowly drops or curls forward when held in position, indicating internal bypass past the piston seals.
- Sluggish tilt response. The bucket moves slower than normal or feels "soft" when curling.
- Hydraulic fluid loss. You're topping off hydraulic fluid more often than usual.
- Unusual cylinder noise. Hissing or chattering during tilt operation can indicate air entering through worn seals.
- Contaminated hydraulic fluid. If wiper seals fail, dirt enters the cylinder and contaminates the entire hydraulic system.
If you notice external leaks combined with bucket drift, that is a strong indicator that multiple seals in the kit need replacement, not just the leaking one.
What Causes Tilt Cylinder Seal Failure on the T650?
Understanding what causes seal wear helps you prevent premature failure after installing a new kit. The most common causes include:
- Normal wear. Seals are consumable components. High-hour machines will eventually need new seals regardless of maintenance.
- Contaminated hydraulic fluid. Dirt, water, or metal particles in the fluid act as abrasives that accelerate seal wear.
- Overheating. Operating at sustained high hydraulic temperatures degrades seal material faster.
- Side loading. Prying, lifting off-center, or working at extreme angles puts uneven stress on the cylinder rod and seals.
- Scored cylinder rod. A damaged or pitted rod surface chews through rod seals quickly, even new ones.
- Clogged hydraulic filter. A restricted filter causes pressure spikes and higher operating temperatures.
Before installing a new seal kit, inspect the cylinder rod and bore for scoring or pitting. If the rod is damaged, new seals will fail prematurely. The rod needs to be re-chromed or the cylinder replaced.
Which Bobcat Models Use a Similar Tilt Cylinder Seal Kit?
Bobcat uses similar tilt cylinder designs across several compact track loaders and skid steers. However, seal kits are not always interchangeable. Dimensions and seal profiles vary by model, serial number range, and cylinder bore size.
| Model | Type | Notes |
|---|---|---|
| T650 | Compact Track Loader | Primary application. Verify by serial number |
| S650 | Skid Steer | Wheeled counterpart to T650. May share cylinder design |
| T630 | Compact Track Loader | Similar frame size. Check cylinder bore dimensions |
| T770 | Compact Track Loader | Larger machine with different cylinder specs likely |
| S630 | Skid Steer | May share tilt cylinder with T630 |
Always verify fitment using your machine's serial number. Bobcat changed cylinder specifications across production runs, so even the same model can require different seal kits depending on build date. If you are unsure, email sales@partsonline.com with your model and serial number for verification.
How Do I Find the Right Seal Kit Part Number for My T650?
Getting the correct seal kit requires matching to your specific cylinder, not just your machine model. Here is how to identify the right part:
- Locate your serial number. It is found on the machine's ID plate, usually inside the cab on the left side or on the frame near the engine compartment.
- Identify the cylinder. The T650 has separate lift and tilt cylinders. Make sure you are ordering for the tilt (bucket) cylinder, not the lift (boom) cylinder.
- Check cylinder dimensions. Measure the cylinder bore diameter and rod diameter if possible. Common T650 tilt cylinder bores range from 2" to 3".
- Cross-reference OEM part numbers. Look for a tag or stamp on the cylinder itself. Bobcat cylinders often have a part number stamped on the barrel.
- Contact us for help. Email sales@partsonline.com with your serial number and we will confirm the correct seal kit.
Aftermarket seal kits cross-reference directly to OEM part numbers, so once you have the OEM number, finding the right aftermarket replacement is straightforward. Browse our Bobcat parts collection to search by part number.
How Do I Replace the Tilt Cylinder Seals on a Bobcat T650?
This is a general overview of the seal replacement process. Consult your T650 service manual for torque specifications and detailed procedures specific to your serial number range.
- Park on level ground. Lower the bucket flat to the ground. Shut off the engine and relieve hydraulic pressure by cycling the tilt controls several times with the engine off.
- Disconnect hydraulic lines. Cap or plug all open ports and lines immediately to prevent contamination. Have rags and a drain pan ready for residual fluid.
- Remove the cylinder. Remove the pin retaining hardware at both the rod end and base end. Slide the pins out and remove the cylinder from the machine.
- Disassemble the cylinder. Remove the gland nut (cylinder head) using the appropriate wrench. Pull the rod and piston assembly out of the barrel.
- Remove old seals. Carefully remove all old seals, O-rings, and backup rings from the piston and gland. Clean all surfaces thoroughly.
- Inspect components. Check the rod for scoring, the bore for scratches, and the piston for wear. Any damage here will cause new seals to fail.
- Install new seals. Install all seals from the kit in the correct orientation. Use hydraulic oil to lubricate seals during installation. Do not use sharp tools that could nick the seals.
- Reassemble and reinstall. Slide the piston assembly back into the bore, reinstall the gland, reconnect lines, and bleed the cylinder.
Safety warning: Hydraulic systems operate at extremely high pressures. Never work on hydraulic components while the system is pressurized. Wear safety glasses and gloves. Consult a certified mechanic if you are not experienced with hydraulic cylinder repair.
What Tools Do I Need to Replace T650 Tilt Cylinder Seals?
Most of the tools required are standard shop equipment. Here is what you will need:
- Socket set and wrenches for removing pin retaining hardware and hydraulic fittings
- Spanner wrench or gland nut wrench specific to the cylinder gland size. Some shops use a strap wrench
- Seal pick set for removing old O-rings and seals without damaging groove surfaces
- Brass drift or soft mallet for driving pins and tapping the piston assembly
- Clean rags and solvent for cleaning all cylinder components before reassembly
- Hydraulic oil for lubricating seals during installation
- Drain pan to catch hydraulic fluid during disassembly
- Torque wrench for reassembling the gland to the correct specification
A hydraulic press can be helpful for installing tight-fitting seals onto the piston, but most T650 tilt cylinder seals can be installed by hand with proper lubrication.
How Long Does It Take to Replace the Seal Kit?
Plan for 2-4 hours for the complete job, from cylinder removal to bleeding the system after reinstallation. Here is a rough breakdown:
- Cylinder removal: 30-60 minutes, depending on accessibility and whether the loader arms are in the way
- Disassembly and seal replacement: 45-90 minutes. Inspection adds time, and stubborn gland nuts can slow you down
- Reassembly and reinstallation: 30-60 minutes. Take your time aligning the cylinder and bleeding air from the circuit
If this is your first time rebuilding a hydraulic cylinder, add extra time for learning the process. The hardest part is usually getting the gland nut off and installing seals without damaging them.
What Are Common Mistakes to Avoid When Replacing Tilt Cylinder Seals?
These are the errors that cause repeat failures and wasted time:
- Skipping the rod inspection. Installing new seals on a scored rod guarantees they will fail again within weeks. Always inspect the rod surface.
- Using sharp tools on seals. Screwdrivers and picks can nick new seals during installation, creating immediate leak paths. Use proper seal installation tools.
- Installing seals dry. Seals need to be lubricated with clean hydraulic oil before installation. Dry seals can twist, pinch, or tear.
- Wrong seal orientation. Some seals are directional. The lip of the seal must face the pressure side. Installing them backwards eliminates their sealing ability.
- Contamination during assembly. Any dirt that gets into the cylinder during reassembly will damage the new seals. Work in the cleanest area possible.
- Not replacing all seals in the kit. Even if only one seal looks worn, replace the entire kit. The other seals are the same age and will fail soon.
- Forgetting to bleed the system. Air trapped in the cylinder causes erratic operation and can damage seals. Cycle the cylinder slowly several times after installation.
Is Aftermarket as Good as OEM for Hydraulic Seal Kits?
Aftermarket hydraulic seal kits are manufactured to meet or exceed OEM specifications using the same seal materials, typically polyurethane, nitrile (NBR), or PTFE depending on the application. The critical factor is dimensional accuracy, and quality aftermarket suppliers machine their seals to the same tolerances as the original equipment.
- Same materials: polyurethane piston seals, nitrile rod seals, PTFE backup rings
- Same dimensions. Bore, rod, and groove dimensions must match exactly or the seal will not function
- Significant cost savings compared to ordering through a Bobcat dealer
- Complete kits that typically include every seal, O-ring, and backup ring in the cylinder, just like OEM kits
Browse our Bobcat T650 parts, and Bobcat Compact Track Loader parts collections for aftermarket seal kits that cross-reference to OEM part numbers.
Frequently Asked Questions
Can I replace just one seal instead of the entire kit?
It is not recommended. If one seal has worn out, the others are the same age and operating under the same conditions. Replace the full kit to avoid tearing the cylinder apart again in a few weeks.
How do I know if my cylinder needs a seal kit or a full replacement?
If the rod is scored, the bore is scratched, or the cylinder barrel is bent, a seal kit alone will not fix it. Seal kits solve leaks caused by worn seals on otherwise good cylinders.
Will a seal kit from a Bobcat S650 fit my T650?
Possibly, since the S650 and T650 share the same frame platform. However, cylinder specifications can vary by serial number range. Verify using your serial number before ordering.
How often should tilt cylinder seals be replaced?
There is no fixed interval. Seals are replaced when they start leaking. Machines in demanding applications or dusty environments may need seal replacement sooner. Regular hydraulic fluid and filter changes extend seal life.
Do I need to drain the entire hydraulic system to replace the seals?
No. You will lose some fluid when disconnecting the lines and removing the cylinder, but you do not need to drain the entire system. Top off the hydraulic tank after reinstallation.
Can I rebuild the cylinder myself or do I need a shop?
If you have basic mechanical skills and a clean workspace, you can rebuild a tilt cylinder yourself. The process is straightforward once you have the right tools. If the cylinder needs re-chroming or bore honing, that requires a machine shop.
How do I verify the correct seal kit for my specific machine?
Email sales@partsonline.com with your Bobcat T650 model and serial number. We will cross-reference the correct seal kit for your tilt cylinder and confirm fitment before you order.
What hydraulic fluid should I use after replacing the seals?
Use the hydraulic fluid specified in your T650 operator's manual. Bobcat typically specifies an ISO VG 46 hydraulic oil or equivalent. Do not mix different fluid types.