Cat Pressure Washer Pump Troubleshooting

Problems tend to follow us wherever we go. So possibilities are high that if you are using a Cat pressure washer you might face troubleshooting one day or another. It’s almost an inevitable thing. But how to get rid of this problem?  Well, let’s find out. 

There can be many reasons for troubleshooting. Some of which are given below. 

  • Low pressure
  • Water leak
  • Oil leak
  • Pulsation
  • Running rough
  • Knocking Noise
  • Premature seal failure

Cat Pressure Washer Pump Troubleshooting

Low Pressure

Multiple reasons could cause low pressure. For example,

Cat Pressure Washer Pump Troubleshooting

1: Worn Nozzle –

 A worn nozzle causes low pressure because of lesser resistance in water flow. A pump is used to generate flow, not pressure. And because the nozzle gets to wear our orifice increases hence less resistance can be seen. 

Solution: Replace the nozzle with a right sized orifice

2: Faulty Unloader –

The unloader is a pressure control valve and it is mainly used to set and maintain the system pressure. A horizontal internal piston helps the flow to move properly or return to the source. A worn or stuck piston could be the reason behind extra bypass flow or low system pressure.


The unloader needs to be kept apart first. Then the valve assembly position should be inspected. If there is any evidence of lack of movement or wear, repair and clean it.

Replace the internal piston if the problem persists. 

3: Worn Seal –

Over time, the seal wears off because of the reciprocating movement of the plunger. Fluid moves to the low-pressure side when that happens to cause lower flow and lower system pressure.

Solution: Replace the seals. Follow the recommendations of preventive maintenance. The pressure gauge may fail because of pressure spikes (over-pressurization). Faulty reading will lead to misinterpreting the system condition. 


Certain things cause pulsation on the pump. Some common reasons for pulsation are :

Rapidly opening & closing the unloader valve in the pump can cause pulsation in the machine. If contaminants and wreckage tuck into the valve it can cause pulsation. Kinks or Blockages in the hose can create pulsation problems. If the washer is not used regularly, pulsation problems can appear. Plugged nozzles can also cause pulsation problems.

Solution :

There’s nothing to panic about pulsation. We’ve found some easy solutions to deal with pulsation. 

1.Clean the unloader valve once a month.

2.Don’t open the pipe or valves too often. Rapidly opening & closing the valves can loosen the Kink.

3.If the valve gets clogged, dirty water can get through the pipe. Try to clean the pipe with detergent suction & vinegar.

 Running Rough

 If high pressure seals the worn, water keeps getting inside the high-pressure chamber and starts to run rough. Unruly water entering the pump of the cat water pressure can cause running rough problems. Pony leakage in the pump can hatch running rough. Entrapped air in the washer pipe propagates this type of problem.

Solution :

1.Reconnoiter the valve of the machine.

2.Clean out the debris of the pump.

3.Maintain the filtration system or replace the valves. 

4.Make sure the water is getting to the pump, not in the high-pressure chamber before starting the engine. 

Knocking Noise 

 Sometimes we hear a clunk in the pipe that’s nothing but a shockwave. When the pipes striking each or adjoining frameworks this sound may occur. Loose pipes can also start knocking noise. Fast-acting valves, worn stop valves generate this problem. The clogged air chamber is also a root to knocking noise. 

Solution :

1.Check the filtration system if there are any obstacles in the water flow.

2.Secure the pipe straps. You can increase the number of pipes for a better flow of water.

3.Don’t mix different materials to harden the pipe.

4.Remove and relocate each valve after cleaning.

Water Leak 

Following are the reasons behind water leaks. 

The main purpose of the seal is to maintain separation between two areas. The internal and the external area of the pump. A worn-up seal can let the liquids leak in those areas. 

Solution: Replace the seals. Check the pump datasheet to find the necessary information needed on how to replace the seal. 

Another reason behind a leak is cracked or crazed plungers. Thermal shocks or pressure spikes are the reason behind this. This can be a big issue as a cracked or craze plunger affects the performance of the pump.  It also affects flow and pressure. And when this happens it allows the liquids to flow past the seals and which causes a leak. 

Solution: Replace the plungers. Also, have a look at the seals if the cracked plungers damaged any of them or not. 

Oil Leak

Multiple reasons can cause oil leaks. Following are some of them and how to solve this problem. 

1. Worn crankcase oil seals – 

Crankcase usually has three crankcase oil seals. Each plunger rods have one and two crankshaft oil seals. The crankshaft of the drive-end operates in oil but not under pressure though. And as time passes by the seals can wear off resulting in an oil leak.

Solution: Inspect the seal thoroughly and replace it. Follow the given recommendations accordingly to complete the process. 

2. Loose drain plug – 

Drive-ends contain either a drain plug or a drain cap. These drain plugs can get damaged due to system vibration. Other reasons also damage the drain plug. Cross-threading the plug or not applying enough torque for a tight seal could also be the reason behind damaging the plug and leaking oil. 

Solution: Inspect the drain plug to find damage. If damage is found replace it or tighten it accordingly. 

3. Loose/damaged oil sight gauge –

The pump drive-ends have an oil sight gauge which helps to monitor the oil level. If it’s loose or damaged it can result in an oil leak. So regular maintenance is advised. Also, the oil level shouldn’t reach below the red dot in the gauge to maintain a proper oil level. 

Solution: Regular inspection is needed. If found damaged then replace it. Tighten it up if the gauge is loose. 

4. Overfilled oil level – 

The pump datasheet contains information about the right amount of oil volume for different pump models. So do check it to maintain the right oil level. The normal oil volume usually fills up one-half of the crankcase. But if the oil overflows it can move through the vented filler cap and build up pressure. 

Solution: Maintain the right proportion of oil volume. To stop oil from exiting through the filler caps vent port, turn the filler cap slightly. 

Premature Seal Failure

Various reasons are guilty of premature seal failures. They are stated below. 

1. Running the pump dry – 

Water is used as a lubricant to maintain temperature and prevent excessive heat. But if a pump runs dry it creates a large amount of heat between plungers and the seals. So it is highly recommended to never run a pump dry as the consequences could be catastrophic. 

Solution: Always keep in mind that water is getting into the pump before starting the engine.  Replace all the worn-up seals. Regularly check the incoming line if it’s facing any kind of obstacles or restrictions. 

2. Overheating caused by excessive bypass – 

When you are running the pump without washing or spraying water into it automatically goes to bypass mode. And once it’s in by-pass mode and water goes to the pump inlet it can create massive heat in a really short period.  This state is sometimes called a “heat rise” and due to this heat pump seals could get severely damaged. 

Solution: Replace the seals and don’t run the pump for more than 3 to 5 minutes when it’s in by-pass mode. Also when that happens adding accessories like a thermal valve or a throttle controller to protect the pump.

3. Excessive water temperature –

Pumps have a maximum level of temperature limit in which they can operate properly. Any more than that then it’ll be damaged due to excessive heat and seals would wear at a dramatic speed. 

Solution: Reduce water temperature in the inlet. If this is not possible then replace the seals with high heat-absorbing capability. Check the datasheet to find which seal options are available for your pump. 

4. Excessive inlet pressure – 

If the water pressure is too much inside the inlet it can create restrictions between seals and plungers. The more the seals squeeze the plungers the more it’ll wear off quickly. 

Solution: An inlet regulator can be used to decrease inlet pressure. It is also advised to install a pressure gauge to keep a track of inlet pressure. 

5. Abrasives in water supply – 

Water that contains abrasion is very hard on seals which causes the seals to damage highly. 

Solution: Add a useful inlet filter so the abrasives are filtered out to a certain amount when it’s not dangerous anymore. 

6. Scored or cracked plungers – 

A very concentric and smooth finish is given while manufacturing plungers. Scored or cracked plungers produce a surface that is irregular and results in seals to wear up quickly. In extreme situations, seals could get completely teared up. 

Solution: Inspect or replace the plungers if necessary. They can be replaced either individually or as a set. Also, check on the seals as they can be greatly damaged by scored or cracked plungers. 

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So, in conclusion, it can be said that no machinery operates accurately all the time. Now and then a little bit of maintenance is mandatory. And by taking the steps mentioned above if a cat pressure washer faces troubleshooting issues they can be solved easily,  quickly, and effectively. 

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