If you have a pressure washer business you will eventually need to change out or repair the pump. There are a few things you should know to make such change outs easy. You may also need to study up on preventative maintenance so that you do not have to worry about pump failure. Your pressure washer probably has one of two different pumps if it is industrial grade. Either a Cat Pump or a General pump; both are industry standards. General is the leader in the industry for sales and many prefer Cat as it sucks better from plastic water tanks.
Your pump is powered by two parallel belts connected to your engine. You should make sure not to starve your pump from water. When the water tank is empty turn off the engine. Starving a pump will burn it out in about thirty-five minutes. The manufacturer says five to ten minutes, but that's not life threatening. Your pump has a safety feature whereby when you are not spraying the water, it will automatically by pass into the tank provided there is enough water for the complete loop. Thank you. We also thought it was one of our great ideas. You should change the oil in the pump every month. Make sure your pressure washer rig is on level ground and fill the pump to the red dot on the center of the eyeglass. Over filling is a really bad idea.
On your pump you will notice six large bolts. Inside of the holes are check valves with springs. After 300-500 hours you should change them. You can do this yourself. The valve kits are .000. It's very easy:
Unscrew bolts
Remove old valve
Replace valve
Make sure to seat the valve evenly
Screw the bolt back in by hand
Make sure the O-ring on the bolt is snug
Tighten with wrench pretty tight
Inspecting The Pump
If you drain the oil and it's got bubbles in it or has turned white, then you have a blown seal and water is getting into the oil because: It overheated due to water starvation; The casing cracked because of vibration; You forgot to change the oil, dummy (0 mistake and one lost day's work if you can get the parts that fast).
Check to see if the belts are tight. If not tighten them. Look for water drips. A slow drip on the exit side of the pump could cost you as much as 150 PSI at the nozzle. A fast drip (two to three drops per second) could be a 250-300 PSI loss at the nozzle. A steady drip stream might be a 500 plus PSI loss. When you see water leaking, fix the leak ASAP. Be sure to use ample Teflon tape when re-tightening fittings. This will stop future leaks, prevent rust and make fittings easy to separate in the future.
A hole in a hose or leak on the inlet side of the pump causes air to get in. The pump will act as if it's starving for water. It might even pulsate. When the water level in your tank reaches a point below the leak in the hose, air will replace the water and you'll get zero pressure. That makes it very hard to wash anything.
Low pressure in the pump can be caused by a number of things; these are by far the most common, but this is not a complete list, generally if you go thru this list the problem will be solved, check the easiest things first such as water supply:
Faulty pressure gauge (Replace)
Out of water (Fill up tank)
Old or worn out tip at gun nozzle (Replace)
Incorrect tip (Remove and replace)
Belt slippage (Tighten belt)
Hose leaks (Fix leaks)
Faulty unloader (Replace)
Mis-adjusted unloader (Re-adjust)
Worn packing in pump (Take it to dealer)
Inline filter clogged with dirt (Clean it)
Obstruction in spray nozzle tip (Remove it)
Chemical metering valve sucking air (Turn it off)
Slow engine rpm (Check engine)
If you have a pulsating issue at the gun or the machine is Fluctuating pressure, this is a completely different problem than low pressure. You should check for: Worn piston packing (Call dealer). Pump sucking air (Fix hole), Blockage in valve (Remove, check valves and take out blockage). If it is fluctuating and very noisy or if your pump is only noisy check for:
Air in suction line (Check water supply and connections)
Broken or weak inlet or discharge valve springs (Call dealer)
Excessive matter in valves (Check and clean if necessary)
Worn bearings (Check and replace. If necessary, call dealer)
Vibrations from mounting (Tighten it. If unable, call dealer)
If you find the presence of water in the pump oil, it could be caused by: Blown pump head seals, High humidity in air (Change oil more often) or Piston packing worn then call your dealer. If water or oil drips from the bottom of the pump this could be a number of things such as Piston packing worn, the O-ring plunger retainer is worn, Oil seal worn, Pump head seal shot or Crack in pump head. If any of these call the dealer and see if they have the parts in stock, you may be able to fix it yourself if you feel confident, if not you will need to leave your machines with the dealer for repairs.
Pump lubrication should be done every three months or 500 hours, which ever comes first. Use SAE 40 weight oil or equivalent for Cat pumps. Use 20/30 weight non-detergent oil for General pumps. It should be hydraulic oil with anti-wear and rust inhibitor additives. The oil level should be checked by looking in the window on the side of the pump. Only fill oil half way to the red dot.
As a pressure washing contractor you must understand how to maintain and repair your equipment, think about it.
