Pressure Washer FAQs
Frequently asked questions about pressure washers and pressure washing.
Use the subjects in the table below to jump to the category you are interested in or simply browse at will.
Q: What's the difference between the Pump brands – Comet and CAT?
A: CAT are branded as 'The Pump with 9 lives' however both American CAT and Italian Comet pumps are tough, durable pumps suitable for commercial use.
Q: How do the components connect?
A: Different manufacturers use different coupling systems for ease of use with their own accessories. Kärcher use a click and twist system, whereas Comet use a BSP threaded system. All NorthStar accessories are interchangeable with all NorthStar pressure washers.
Q: Can I use my electric pressure washer on an extension lead?
A: For smaller consumer models this should be fine, however some models need a 15amp supply - in those cases make sure it is run from ring main (not a spur) and avoid using extension leads.
Q: Can I extend the hose and what happens to pressure if I do?
A: It is not recommended as this will reduce the performance of your pressure washer, however, it is possible! You would lose 14.7PSI (1BAR) for every 10m extension. Make sure the coupling system doesn't allow for further drops in pressure. Quick couplers used on the NorthStar range mean you can use either a 15m extension OR 2x7.5m extensions without a further drop in pressure.
Q: How can I increase the pressure?
A: Depending on the make and model you may be able to fit a turbo nozzle which could double the pressure - check our Nozzles category for various types.
Q: Can I run my pressure washer on red diesel?
A: Yes, as long as it is a diesel pressure washer. However it will require more frequent cleaning as a result.
Q: What does Oil Alert mean?
A: Oil alert is a system installed on some fuelled engine pressure washers, to alert you if the oil pressure is low and prevent damage to the engine or pump. It is commonly found on Honda engines.
Q: I want to use for trade use - do you offer spares or service backup?
A: Northern Tool UK carries a full range of spares for NorthStar and Comet pressure washers. The smaller consumer models are generally not user serviceable, but parts may be obtained direct from the manufacturer. Northern Tool UK has a range of service protection plans which can be taken out when your washer is purchsed. Click here to view the terms and conditions.
Q: What do the different nozzles do?
A: Different nozzles control the shape of the spray so a 0°nozzle will produce a strong column of water, whereas a 40°nozzle will produce a wide fan or broad triangle shape of about 40°, 15° will produce a smaller fan shape and so on.
Q: What do I need to get the machine working out of the box?
A: Electric models usually plug in and go. Fuel driven engines will need the correct fuel, oil in the pump and oil in the engine. Hot pressure washers need diesel fuel AND an electrical connection.
Q: What is the warranty period?
A: It depends on how it is being used. Small consumer models will generally include a 12months consumer warranty. Engine powered pressure washers with a Honda GC engine usually come with 1 year consumer use and/or 90day commercial use. Those with a Honda GX engine usually come with 2 years consumer use and/or 1 years commercial use warranty (but only against manufacturer defects, not seals and perishable parts). Consumables and accessories are typically covered by 90 day warranty, or 30 days for seals.
Q: What is the difference between a Honda GC and Honda GX engine?
A: Honda GC engines (with the black engine cover) are for consumer and light commercial use. Honda GX engines (with the red engine cover)are for use in commercial up to industrial applications. Also see the note above on warranty.
Q: What is meant by a 'geared' pressure washer?
A: If the pump is geared, it means it can change up and run more quietly (at lower revs) whilst producing the same amount of pressure. Although some people like this feature it does add another element which could potentially fail over time.
Q: Can I adjust the pressure of my pressure washer?
A: Yes, although it does vary according to the manufacturer. With NorthStar pressure washers you can increase the pressure with different pressure nozzles. Changing these increases the pressure without adding to the wear and tear of the pump. Some models can also be increased by use of the Unloader knob, however this adds to the strain on the engine and pump and is not recommended.
Q: What is a recoil start?
A: Any engine started with a pull cord, is called recoil start. Some pressure washers offer electric start, but generally the larger commercial and industrial models.
Q: Can I feed my pressure washer from a barrel or tank?
A: Most pressure washers require mains pressure, however some can use a water butt or barrel together with a gravity feed kit. If your mains pressure (usually 12LPM) is lower than the flow rate of your pressure washer then you may need to use a gravity feed kit to prevent the water reservoir running dry and damaging your pump.
Q: What do I need to feed my pressure washer from a barrel or tank?
A: Most pressure washers require mains pressure water, however some can be run from a water barrel or butt, by using a gravity feed kit.
Q: Are assembly and usage instructions included?
A: Yes. You should also find them on the Northern Tool UK website along with the images and description of the pressure washer.
Q: Can I syphon water using a pressure washer?
A: Pressure washers DO NOT suck, so if you wish to use them to syphon water then you will need a syphon kit. CALL CUSTOMER SERVICES on 0845 605 2266 for more info.
Q: Is it safe to store pressure washers with the fuel still in them?
A: No. If you are storing your pressure washer for more than a few days then you should remove the fuel and store it in a safe container as unleaded fuel can become sludgy over time. In winter you must ensure there is no water left in the pump and hoses because if it freezes it could damage the seals, split hoses or even crack the engine.
Q: Do my nozzles need cleaning, and how do I do it?
A: Nozzles are fairly hard wearing and made of stainless steel so they probably won't need cleaning. If they do, debris can be blown free using an airline or you could use an Ultrasonic Cleaning Tank.
Q: When do I change the oil?
A: First oil change: 15-20 hours or after 3 months, whichever comes first. Following oil changes should be every 200 hours or at least once a year. The oil should be changed,regardless of time, if it is milky-looking or if the level is low. (The sight glass is on the side of the pump.) If the unit is being used frequently or commercially, you will want to change the oil more often. It is imperative that the oil is clean and water-free at all times.
Q: What type of oil do I use?
A: Pumps use a 30-weight non-detergent pump oil. The use of motor oil will result in the oil becoming milky white in color. Units with gearboxes on the pump use 80W-90 gear lube oil. Do not confuse the gearbox with the actual pump when refilling or vice-versa.
Petrol-powered pressure washers use an SAE 30W motor oil (10W-30) in the engine. Always consult the engine manual for specific instructions and be careful to put the correct oil in the correct place.
Q: I'm not getting any pressure. What do I need to check?
A: Generally, all pressure washers 1,500 PSI or less use a push/pull type nozzle adjustment. Turning the nozzle sleeve adjusts the spray fan pattern. If the sleeve is pulled back, the unit is in low pressure. If the sleeve is pushed forward, the unit is in high pressure. A quick check of the nozzle holder to make sure the nozzle is in place will help as well. The nozzle looks like an Allen screw with a hole in the middle of it.
For 2000 PSI units and above, use quick-couple nozzles that can be exchanged with each other depending on the application. These nozzles are color-coded for easy use.
Black - low pressure and soap injection.
Red - 0° fan pattern (high pressure).
Yellow - 15° (high pressure).
Green - 25° (high pressure).
White - 40° (high pressure).
The engine must be running at full speed for the pump to operate properly. If the engine is not running at full throttle, the pump will not be able to produce the proper flow of water to give the pump full pressure.
Sometimes the keyway may slip out from the engine shaft and pump sleeve. To check the keyway, remove the four bolts that hold the pump to the engine and slide the pump off. A quick visual inspection will verify if the key is in place.
After a certain amount of use and time the water seals may begin to leak. This is a normal occurrence as the seals are considered a wear item. A seal leak can be confirmed by looking between the pump and the manifold to see if water is dripping down. If so, it is time to replace the seals.
Q: My engine will not start. What do I do?
A: The most frequent cause is trying to use a pressure washer with an oil alert system on an incline - make sure it is on a flat surface first.
Next, check it has been fuelled.
Pumps without a pressure release need to have the trigger pulled while starting the engine. Make sure the throttle, petrol and choke are all on. If all this checks out, inspect the air filter. If this is soaked with oil, replace the filter along with the spark plug. The last thing to check is the oil level. If the engine has a low-oil alert, just add more oil and the engine should start up.
Q: I cannot get any soap injection. What should I do?
A: Make sure the nozzle is correctly adjusted for low pressure.(Push/pull type or black quick-couple nozzle.)
Make sure the soap injector metering valve is turned on.
Make sure that the soap solution is the consistency of water.
Make sure that the low-pressure tip is not clogged.
If the above steps are followed to no avail, remove the high-pressure hose and run the pump/engine with the soap injector turned on to see if it works without the hose. If it does, replace the hose, gun, wand, nozzle and tip, in that order, to determine which item is defective.
Q: How do I protect my pressure washer for winter?
A: Prepare the pressure washer for storage by running a 50/50 mix of water and anti-freeze into the unit. This will keep the internal parts lubricated, protected from rust, and prevents the pump from freezing. Please use environmentally friendly anti-freeze whenever possible using the following procedure:
Mix anti-freeze and water at a 50/50 ratio.
Connect a short piece of garden hose (2-3 feet long) to the water inlet fitting of the pump. Use a funnel to pour the anti-freeze solution down the hose.
Disconnect the high-pressure hose from the pump, if it is still on the pump. Drain it and store it in a warm, safe place.
Pour the anti-freeze solution down the funnel and into the short hose.
Start the machine and let it draw the solution through the pump. This can take up to 2 minutes. Shut the pressure washer down when the solution begins to spray from the pump outlet.
The machine is now ready for storage. Simply flush it out with clean water when you are ready to begin using it in the spring.
Q: My unloader is stuck open. How do I clean it out?
A: follow these steps:
Unscrew the large red cap above the manifold.
Remove the spring and washer that were under the cap.
Unscrew the large brass bolt from the manifold and pull it out.
Clean out the unloader valve in warm, soapy water and inspect for any debris or metal burrs. Remove any foreign materials.
Flush out the cavity the unloader was in by running garden hose water through the pump.
Use a torch to inspect the cavity for any debris and clean it out.
Reassemble the unloader, taking care not to strip the brass threads. Make sure the red knob is screwed down tightly (hand-tightened).
Q: What is the safety release valve?
A: The safety relief valve is the designed weak point in the pressure washer. If the unloader malfunctions, the safety relief valve will open and relieve system pressure safely.
Q: What is the Quick Couple Chemical Injector?
A: One of the most common failures in a pressure washer system is the chemical injector. There is a small orifice in the injector that can become blocked with dried up soap rendering the chemical injector inoperable.
The advantage of the quick-couple injector over the hard-plumbed style is that you can remove the quick-couple injector in seconds with no tools. When it becomes blocked up, simply throw it in a bucket of water overnight and the chemical will dissolve.
The second advantage of a quick-couple chemical injector is the option of removing the chemical injector and boosting pressure by 5 to 10 percent. This is accomplished by removing the small orifice that the chemical injector works with.
Q: Which is best Ceramic or Non-Ceramic Plungers?
A: The plunger is the moving part of a pressure washer pump that travels back and forth between rubber seals to create the flow and pressure of a pressure washing system. The material that is used on all industrial grade pumps is ceramic. This material has excellent properties that allow it to be extremely smooth — extending the life of the seals. Ceramic also does not wear. Non-ceramic plungers will wear and reduce the life of the seals. They are found only on pumps designed for short life.