Komatsu PC200-6 Seal Kit: Complete Guide to Choosing the Right Kit

The Komatsu PC200-6 is a classic excavator model with a large installed base. As the machine ages, the boom, arm, and bucket cylinders may develop oil seepage, leakage, weak operation, or cylinder drift. In many cases, it is not necessary to replace the entire hydraulic cylinder. As long as the piston rod, cylinder barrel, and guide components are in good condition,Choosing the correct Komatsu PC200-6 Seal Kit is important for preventing leaks, premature seal failure, and unnecessary repairs.

However, the PC200-6 does not use only one type of repair kit. Before ordering, you must confirm the cylinder position, cylinder part number, and specific dimensions.

一. Common PC200-6 Seal Kit

Seal Kit Type	Name	Main Purpose
Main Hydraulic Pump	Hydraulic Pump Seal Kit	Repair the main hydraulic pump and replace internal seals, O-rings, etc.
Hydraulic Pump Regulator	Pump Regulator Seal Kit	Repair the hydraulic pump regulator and servo mechanism
Pilot Pump	Pilot Pump Seal Kit	Repair the pilot gear pump and related sealing components
Main Control Valve	Main Control Valve Seal Kit	Repair O-rings, backup rings, and seals inside the main control valve
Center Joint	Center Joint Seal Kit	Address internal and external leakage in the center joint
Swing Motor	Swing Motor Seal Kit	Repair the internal sealing system of the swing motor
Travel Motor	Travel Motor Seal Kit	Repair internal seals in the left and right travel motors
Boom Cylinder	Boom Cylinder Seal Kit	Repair the hydraulic cylinder that controls boom raising and lowering
Arm Cylinder	Arm Cylinder Seal Kit	Repair the hydraulic cylinder that controls arm extension and retraction
Bucket Cylinder	Bucket Cylinder Seal Kit	Repair the hydraulic cylinder that controls bucket curling and dumping
Pilot Valve	Pilot Valve Seal Kit	Repair the pilot control valve and internal seals

1. Hydraulic Pump Seal kit

The main hydraulic pump is a very important component of the PC200-6 hydraulic system.

As operating hours increase, the hydraulic pump may develop the following problems:

1. Slower operating speed
2. Insufficient hydraulic pressure
3. Oil leakage from the pump body
4. Abnormal noise
5. Excessive oil temperature
6. Poor coordination during combined operations

2. Control Valve Seal kit

The Main Control Valve controls hydraulic functions such as the boom, arm, bucket, swing, and travel. After long-term operation, aging O-rings, backup rings, and seals inside the valve body may cause:

1. Increased internal leakage
2. Weak operation
3. Abnormal operation of an individual function
4. Poor coordination during combined operations
5. External oil seepage from the valve body

3. Center Joint Seal kit

The center joint transfers hydraulic oil to the left and right travel systems on the lower structure while the upper structure rotates continuously. If the internal seals are worn, common symptoms include:

1. Weak travel on one side
2. Different travel speeds on the left and right sides
3. Machine veering while traveling
4. External oil leakage
5. Internal oil cross-leakage

4. Swing Motor Seal kit

The swing motor drives the excavator upper structure to rotate. If there is weak swing performance, oil leakage, or abnormal noise, the internal motor components should be inspected further rather than replacing only the seals.

5. Travel Motor Seal kit

The PC200-6 has one travel drive system on each side. The Travel Motor Seal Kit is mainly used to address:

1. Travel motor oil leakage
2. Aging internal seals
3. Hydraulic oil entering the reduction gear mechanism
4. Abnormal travel pressure

If the gears, bearings, or pistons are also severely worn, replacing only the Seal Kit may not solve the problem.

6. Boom / Arm / Bucket Cylinder Seal Kits

The Boom Cylinder Seal Kit is used for the boom cylinder and controls boom raising and lowering.

The Arm Cylinder Seal Kit is used for the arm cylinder and controls arm extension and retraction.

The Bucket Cylinder Seal Kit is used for the bucket cylinder and controls bucket digging and dumping.

The Seal kits for these three cylinders are not interchangeable. In addition, this model is available with 6D95 and 6D102 engines, so you need to accurately identify which engine model your machine uses.

Therefore, when confirming a Seal kit, the following order of priority is recommended:

① Part Number
② Component Model / Nameplate
③ Machine Serial Number
④ Machine Model
⑤ Dimensions / Photos

Providing the component nameplate or the original part number is usually the most accurate method.

二.Common Seal Materials Used in PC200-6 Seal kits

Seal Component	Common Material	Main Function
Rod Seal	PU / TPU Polyurethane	Prevents hydraulic oil from leaking along the piston rod
Piston Seal	PU / PTFE + NBR/FKM	Maintains pressure between the two chambers and prevents internal leakage
Dust Seal	PU / NBR	Prevents mud, sand, and dust from entering the cylinder
O-Ring	NBR / FKM	Static sealing
Backup Ring	PTFE / Nylon	Prevents the O-ring from being extruded under high pressure
Wear Ring	PTFE / Phenolic / Composite	Provides guidance and prevents direct metal-to-metal contact

三. Consider the Working Conditions

For machines operating in mining, quarrying, high-temperature environments, or under long periods of continuous operation, seals with excellent wear resistance and high-temperature resistance should be selected.

四. Avoid Choosing Based on Price Alone

Low-priced seal kits often use ordinary recycled rubber or PU with insufficient hardness; they are only suitable for temporary emergency repairs or situations where a used excavator is being sold.

Compared with repairing the cylinder again after a few months, purchasing a slightly better-quality seal kit is usually more economical.

五. Inspect the Cylinder Before Installation

A new seal kit cannot repair damaged cylinder components. Before installing the seals, check:

1. Whether the piston rod has scratches or chrome-plating damage
2. Whether the cylinder barrel has scratches
3. Whether the guide bushing is excessively worn
4. Whether the seal grooves are damaged
5. Whether the hydraulic oil is contaminated

If the piston rod or cylinder barrel is severely damaged, replacing only the seal kit may result in leakage again shortly after installation.

六. How to Choose the Correct Komatsu PC200-6 Seal Kit?

1.Genuine Komatsu Parts

Advantages: Accurate fitment, stable quality, and reliable service life.

Disadvantages: Higher price, and some models may have limited stock or longer lead times.

2.China-Made Aftermarket Parts

Advantages: High-quality PU, NBR, and PTFE sealing components provide excellent resistance to wear, pressure, oil, and temperature, making the kit suitable for demanding excavator hydraulic cylinder applications.

Disadvantages: The main disadvantage of low-cost China-made PC200-6 cylinder seal kits is inconsistent material quality and dimensional accuracy, which may result in shorter service life, leakage, premature wear, or seal failure under heavy-duty operating conditions.

Item	Genuine / OEM	High-Quality China-Made
Material Consistency	⭐⭐⭐⭐⭐	⭐⭐⭐⭐
Dimensional Accuracy	⭐⭐⭐⭐⭐	⭐⭐⭐⭐
Wear Resistance	⭐⭐⭐⭐⭐	⭐⭐⭐⭐
High-Pressure Extrusion Resistance	⭐⭐⭐⭐⭐	⭐⭐⭐⭐
High-Temperature Resistance	⭐⭐⭐⭐⭐	⭐⭐⭐⭐
Service Life	Long	Medium to Long
Batch Consistency	Very High	Relatively High
Price	$$$$$	$$–$$$
Cost-Performance	Medium	High

FAQs

1. Can the correct Seal kit be confirmed using only the PC200-6 machine model?

It is not recommended. PC200-6 only identifies the machine series and cannot accurately determine the required Seal kit.

2. Are the boom, arm, and bucket cylinder Seal kits for the PC200-6 interchangeable?

Usually not. The three cylinders have different dimensions and sealing structures, so the corresponding Seal kit should be confirmed separately.

3. Are China-made Seal kits always lower quality than genuine parts?

1. No. The quality of China-made aftermarket seals varies greatly.
2. Seal kits made from high-quality PU, NBR, PTFE, and composite materials can meet many PC200-6 repair requirements if dimensions, tolerances, and material quality are consistently controlled.
3. What should really be avoided are extremely low-priced products without stable quality control.

4. Why does the cylinder leak again shortly after replacing the Seal kit?

Possible causes include:

• Incorrect Seal kit model
• Scratched piston rod
• Damaged chrome plating
• Worn guide bushing
• Scored cylinder barrel
• Incorrect seal installation direction
• Contaminated hydraulic oil
• Abnormal system pressure
• Poor seal material quality

Therefore, when leakage occurs, you should not assume that simply replacing the seals will definitely solve the problem.

5. Can I replace only the Seal kit if the piston rod is scratched?

If there are only very slight surface marks, the decision can be made based on the actual condition.

If there are deep scratches, rust, pitting, or chrome-plating peeling:

It is recommended to repair or replace the piston rod first; otherwise, the new Rod Seal may be damaged again very quickly.