Tips on Maintaining and Repairing a Pressure Washer

A pressure washer is quite a sophisticated machine and will require varying degrees of maintenance depending on the type of pressure washer (some call it a power washer). A gas-powered pressure washer will obviously require more regular maintenance. This is because a gas engine needs to be serviced at regular intervals. An electric pressure washer won’t require the same level of service.

I’m not going to be covering engine service and repairs in this article because this is not specific to a pressure washer. There are plenty of how to guides for engine repairs and maintenance. Your owner’s manual will usually provide you with the relevant information pertaining to regular service and troubleshooting for the engine fitted to your power washer.

Regardless of the type of power washer that you’re using, there are a few procedures that need to be carried out from time to time and repairs will sometimes be necessary. Most importantly, prevention is always better than cure. So we’ll start with some tips on how to prevent problems from occurring when using your pressure washer.

Preventative Pressure Washer Maintenance

A pressure washer uses a piston or plunger pump. This can be an axial cam pump or a triplex pump. Both these types of pumps use pistons to force the water into a chamber which is then directed by means of a valve to the outlet manifold.
The main difference between a triplex pump and an axial cam pump is that a triplex pump is that a triplex pump always uses three pistons in a triplex format. This means that each piston increase the pressure produced by the previous one. This gives the pump a very smooth pressure and flow, without any pulsing. An axial cam pump can often use three pistons but this not imperative. Triplex pumps usually have better valves, seals and cams, making them heavier duty machines. Though most of the commercially available pressure washers that we use at home make use of axial cam pumps.
Also make sure that the hose connection to your power washer is properly secured as it can suck air into the system. If your pressure washer has connectors that screw on, be sure not to damage the thread. If you feel resistance when starting to screw the fitting into position, the thread is not properly aligned and this will strip (cross-thread) the fitting. So if you feel that you’re turning too hard on the fitting, stop immediately, turn the fitting back out and start over.
Dirt in the water can also damage the components inside the pressure washer. Some power washers have a mesh filter at the water inlet. Though many don’t. Generally, your municipal water supply is clean and free of harmful particles, but you can’t always be sure. If you know that the water in your area isn’t that great, or just want to be sure, you can fit an inline water filter to the water supply. These are not expensive and easy to install. You don’t need a very fine filter, a regular mesh filter will do just fine.
It’s very likely that you’ll be using detergent with your pressure washer. You need to remember that harsh detergents (like engine cleaners) can harm the seals inside the pump and other components fitted to your pressure washer. It’s always best to use the detergent recommended by your power washer manufacturer. Though any dishwashing liquid is fine, these are mild detergents.
Your unloader valve or pressure regulator controls the pressure supplied from the pump to your high-pressure outlet. This is usually a handle that you turn in or out to control the pressure. This is a spring-loaded valve and rust can sometimes buildup inside it. To keep the regulator functioning properly, I recommended turning it all the way out to its minimum pressure and the back in to the full pressure setting periodically. This will free up any corrosion residue that may collect inside the pressure regulator.

These are all simple and easy procedures to follow. Taking the time to do these few things will help prevent a lot of headaches moving forward and will prolong the life of your power washer.

Common Problems Associated with Pressure Washers

As with any device that handles water, leaks are a common cause of problems. Very often you may have a water leak at the inlet or outlet connector. If your pressure washer has regular screw on water fittings, it is often the washer that may have worn down. It’s really easy to remove the washer, take it your hardware store and get a replacement washer. It’s just as easy to replace.
Quick connect fittings are not as easy to diagnose or repair. Though there are a few simple procedures to follow. Dirt in the fitting is the most common reason why leaks occur. So the first step is to rinse the fitting with clean water, do this several times to be sure. Usually a quick clean of the fitting will stop the leak.
Another issue that can cause a quick connector to leak can be a twisted or damaged “O” ring. These are cheap and easy to find. Though “O” rings come in all sorts of sizes. The diameter or thickness of an “O” ring can’t be accurately determined with the eye – the differences can be really small. So you’ll always need to remove the “O” ring and take it to the store as a sample.
A female fitting will have an “O” ring seated into a groove running along the inner wall of the fitting. With a male fitting, the “O” ring is usually visible - seated into a groove on the outer wall. To remove the “O” ring, you simply work it lose with a blunt-tipped screwdriver or similar item. When replacing an “O” ring, never use a sharp tool. Try to use your fingers. If this is not possible, use a plastic lever. Lubricate the “O” ring with a mild liquid detergent before fitting it. This will prevent it from twisting and allow it to fit into position more easily.
If none of the above steps resolve the issue, you’ll probably have to replace the fitting.
Sometimes your pressure washer won’t switch on and this could be for a number of reasons. First, you’ll need to start with the basics, as you would with any electrical appliance. Is the pressure washer plugged in? Does the power outlet have power? The circuit breaker may have tripped. Is your extension cord in good working order? Is the on/off switch in the on position?
If the answer to all the above questions is yes, then it’s likely that one of the pressure washer’s built-in protection mechanisms is preventing it from starting.
Your pressure washer is most probably fitted with GFCI protection to prevent accidental electrocution. This may be automatic, in which case it will reset itself when the situation is safe. You may have to reset manually. Firstly, you need to find the cause of the problem. GFCI protection will interrupt the power supply if a power leakage to ground is detected. This can often be because the electrical components are immersed in water or an electrical cable is damaged, exposing the copper wire. Check that the machine is dry, though you might not always be able to see if water has seeped inside the outer casing. To makes sure, you can always use a leaf blower or hair dryer and blow air into every opening on the power washer.
Inspect all electric cables to ensure that they are not damaged. Now try resetting the GFCI protection. If this doesn’t work, you should take the pressure washer to a certified service agent.
Power washers usually have a run-dry protection sensor. This will prevent the pump from switching on if it doesn’t have water flowing into it. Check that the water supply is on and that there are no blockages in your hosepipe or the water inlet.
Many pressure washers will also have an overheating protection sensor. If the motor or engine gets too hot, the power washer will automatically switch off. If you feel that the area around the engine or motor is particularly hot. Leave the power washer to cool down and try start it again when it’s sufficiently cooled.
A four-stroke gas engine will often have low oil protection and you should check your engine oil level to ensure that the engine has enough oil.

Advanced Pressure Washer Issues

This section of the article is aimed at the more technically minded owner. So you may prefer to have a professional check these issues for you.

If your power washer loses pressure or the pressure is intermittent, you should to check the unloader valve before anything else. Dirt or rust inside the valve can cause it to jam or stick.
To check the valve, you’ll probably have to separate the pump from the motor or engine. The pump will have a flange with four bolts attaching it to the motor. You’ll need to remove these bolts and disconnect any pipes that prevent the pump from being removed. The pump should slide off the shaft quite easily. If you feel a lot of resistance when pulling the pump off, there’s probably rust on the shaft. Try tapping around the flange gently with a hammer whilst twisting and pulling on the pump. This should loosen the rust and allow the pump to come off smoothly. If this doesn’t work, you’ll need to use a pulling tool to remove it or you can try levering around the perimeter of the flange.
If the unloader valve is connected to the outlet pipe, it’s going to be easy to unscrew it. Often the valve is fitted to the pump head assembly and this will mean removing this before you can access the unloader valve. Be careful when removing the pump head bolts because there are springs behind it and an oil reservoir. You’ll want to remove the bolts evenly to prevent the springs from pushing out irregularly.
Once you have the unloader valve freed from the pump, you need to open it. Remove the adjustment handle. It will have a screw or fastening clip at the top. With the handle off, you’ll have 2-3 screws or bolts exposed. These hold the valve assembly together. Loosen these and remember that you’ll have a spring pushing up from the inside. Once open, the spring will drop out and you’ll see the valve mechanism inside the cylinder. You’ll need to use a long nose plier to pull this out. It doesn’t come out very easily because there are “O” rings pressing against the side of the cylinder.
Once you’ve opened the valve, I recommend replacing the “O” rings with new ones. Check for dirt or damage inside the valve. Clean it and replace any damaged items before reassembling the valve. You’ll follow the above procedures in reverse for reassembly.
Another problem that could affect the pressure is the pump valves. You can check these by removing the pump and the pump head assembly as described above. With the head assembly exposed, the valves fall out of their slots quite easily. Check that their springs are working properly and that there’s no dirt in the valves.
Finally, you may have a cracked or broken piston. To change pressure pump pistons is fairly complicated and you’ll have to remove all rubber and plastic seals from the pump head. Do this gently, by levering everything out with a screwdriver. Once the pistons are exposed, you’ll see a bolt at the top of each piston. You need to loosen these and the use a long nose plier to pull the pistons out. There is going to be a good deal of resistance, so work patiently and carefully. A cracked or broken piston needs to be replaced. You can get these from the agents that supply the pump along with ring kit that goes with it. While you have the pump open, I suggest changing all the rings. You don’t want to do all this work again in a hurry.