A chemical injector uses a small spring and ball under the hose barb as a check valve to control the chemical in and water from coming out. The check valve closes when your pump operates at high pressure, preventing water from flowing out of the chemical injector hose barb. A venturi effect (vacuum) opens the check valves when your pump operates at low pressure, drawing in the chemical. Some things that can reduce or prevent the chemical draw are:

• Having too large of a nozzle resulting in low pressure
• Having too long of a discharge hose (usually over 100 ft) creates too much back pressure
• Injector check valve stuck - be sure to clean with fresh water before storing

Pumps mounted to engines/motors for an extended period of time can be difficult to remove. For step by step instructions on removal, review the literature link below.

When the trigger is released on the gun, a check valve inside of the unloader discharge port closes and traps pressure in the hose. The unloader switches to the unloaded position and runs at low pressure until the trigger is squeezed again. .

If a pump has good pressure when the trigger is squeezed, but the engine starts to bog down, or stall when the trigger is released, inspect the check valve inside of the unloader discharge port. If the check valve  is stuck, or worn, it may not seat properly and the unloader will not shift in to the unloaded position. An inexpensive check valve repair kit is usually available for the unloader. Consult the unloader, or pump data sheet (integral unloader) for repair kit information.

Cat Pumps recommends the use of its specially formulated High-Pressure Pump Oil. Cat Pumps custom-blended, High-Pressure Pump Oil is exclusively designed, tested, and proven to maximize the life of Cat Pump products. This special formulated, premium-grade, petroleum-based, ISO 68 hydraulic oil contains an advanced additive package to protect against wear, oxidation, rust, and corrosion.

• Anti-wear additives protect metal to metal drive surfaces, extending drive life
• High oxidative and chemical stability resists deposit formations and provides consistent fluid performance
• Premium anti-corrosion additives offer protection in the most demanding operating environments

Cat Pumps Genuine Crankcase Oil Part Numbers:

• 6100 Case of (12), 21 oz. bottles
• 6105 Case of (2), 2.5 gal. bottles
• 6107 (1) 21 oz. bottle
• 6109 (1) 30 gal. drum

Previously, select recommended alternative oils were acceptable. Some oil manufacturers changed their oil formulas, leading to pump problems. For this reason, Cat Pumps does not recommend the use of any alternative oils.

Each pump has a sight glass; the oil level should be in the middle of the sight glass when the pump is not running.  You can also reference your pumps datasheet which lists the specific amount each pump requires.

Although some synthetic oils may be acceptable, Cat Pumps does not recommend the use of them. We only recommend the use of Cat Pumps brand oil in any Cat Pump. Our special formulated premium grade, petroleum-based, ISO 68 hydraulic oil contains an advanced additive package to protect against wear, oxidation, rust and corrosion.

Forward rotation (towards the manifold) is recommended to allow optimum lubrication of the crosshead area, ensuring exceptional drive end life. If your installation does not allow for forward rotation, reverse rotation is acceptable if the crankcase oil above the red dot in the oil gauge. This assures adequate lubrication.

No, crankcase oil seals typically last the life of the pump and are not considered a wear item such as the water seals in the fluid end of the pump.

Although the oil seals can be removed through the front of the crankcase, Cat Pumps recommends that the drive end be taken apart and the plunger rods be removed so they are not scored during the process.

No special tools are needed. Standard metric tools are required.

We have an online resource to help identify your pump components and accessories by clicking here.

Removal of the pump manifold and measurement of plungers, or cylinders (piston pumps) may be required for complete identification. A stamp number on the end of the crankshaft will be required too. For detailed information on how to identify your pump when the model label is missing, refer to the Pump Identification Reference Bulletin at the link below.

The pump model can sometimes be identified just by sight by one of our Technical Support specialists. Emailing us some pictures of the pump may help point you in the right direction. Contact techsupport@catpumps.com.

No, repairs would need to be sent to an authorized service center or where you purchased the equipment.  A warranty claim would need a return authorization through a service center or authorized distributor.

This topic is covered in our pressure washer troubleshooting section which can be accessed by clicking here.

A chemical injector uses a small spring and ball under the hose barb as a check valve to allow the chemical to pass to the system when there is sufficient pressure drop across the injector assembly. This happens when the discharge spray is reduced, otherwise injection does not take place.  Pressure can be lowered by using an oversize nozzle or by opening a variable pressure wand.

Conditions that prevent the chemical draw include:

• Incorrect nozzle size to create low pressure
• Too long of discharge hose (usually 100 ft or more), creating too much back pressure
• Injector check valve stuck, likely due to debris or poor cleaning

The typical cause of a pump leaking water between the manifold and the body of the pump is water making its way past the low pressure seals. This is usually caused by the low pressure seals being worn. Other reasons could be the damaged seals or a cracked plunger. Low pressure seals and plungers should be inspected and replaced if damaged.

The small O-ring is located in front of the plunger on the plunger retainer bolt.

One seal kit is required per pump.  A typical seal kit contains (3) low pressure seals, (3) high pressure seals, (3) O-rings for the seal case and (3) O-rings for the plunger retainer.

Every pump has a seal kit available; seal kit numbers are item #300 on the pump data sheet.

Loose seals on the plunger are a sign of worn seals. Typical symptoms include water leaks or low system pressure. 

Pressure washer pumps typical do not need any special tools. There is a seal case tool for larger gearbox or belt driven pumps such as the 310, 340 and 350 (5 frame) or 530, 550, (7 frame), etc.

Pressure washer pumps can take either one or two valve kits depending on the valve style.  Pumps with a stacked valve design require one valve kit and pumps with a split valve design require two kits.  This can always be verified by looking at item number #310 on the pump data sheet and checking the chart on the far right for the number required.

Valve kit part numbers are located on the data sheet under item # 310. Be sure to verify the number of kits required before ordering. 

Damage can occur to the springs or spring retainer, but most often damage is found between the valve and seat in the sealing surface between them.

The torque specification for the valve plug can be found on in the service manual for your pump or in Technical Bulletin 74 on the Cat Pumps website.

A valve assembly can be disassembled by pulling it apart, in some cases using a small flat screw driver. Insert the screw driver between the spring retainer (plastic cage) and the valve seat and turn it slightly. The valve should come apart.  The valve assembly easily snaps back together.

Yes. Warm water with a mild detergent will work.