A triplex pump that gets looked after runs for thousands of hours. One that does not usually dies from something preventable, and in our experience it is nearly always one of five things.

1. Never let it run dry

Plunger seals are lubricated by the water going through them. Run the pump without water and they overheat and glaze, and that happens in well under a minute with no warning noise.

The startup order that prevents it:

1. Open the water supply fully.
2. Hold the trigger open with no nozzle installed and let water flow through until the stream is steady and free of bubbles. You are purging air.
3. Start the motor or engine.
4. Run at low pressure for a minute, then fit the nozzle.

Most people do this in the opposite order. That order is where a lot of seal kits come from.

2. Do not idle in bypass

With the trigger closed, the unloader recirculates water back through the pump. It has nowhere to lose heat, so it warms up continuously. Two minutes is about the limit. Past that you are cooking the seals.

The rule is simple: if you are putting the gun down for more than a minute or two, shut the machine off. Restarting is free. Seals are not.

This is worse on small direct-drive pumps, where there is less water and less metal to absorb the heat, and worse again on hot water systems where the water is already at 185°F.

3. Protect the inlet

Cavitation is water vapor bubbles forming in the pump and collapsing against metal and ceramic. It happens when the inlet cannot supply what the pump is trying to draw. It pits valve seats and cracks ceramic plungers, and it does that damage while the pump still appears to be working.

What prevents it:

• Full-bore supply hose, kept short
• Tap fully open, no kinks anywhere in the run
• Inlet filter checked and cleaned on a schedule, not when you remember
• Flooded suction, meaning a supply tank above the pump rather than below it
• No air leaks at inlet fittings

The warning sign is a rattling or knocking sound from the pump, or a pulsing jet at the gun. If you hear it, stop and fix the supply. Do not work through it.

While you are at it: grit is the other inlet problem. A torn or missing screen lets sand into the valves, where it holds them off their seats and scores plungers.

4. Oil, and reading what it tells you

Use pump crankcase oil, not motor oil. Pump oil is non-detergent for a reason: detergent oils hold water in suspension, and in a pump crankcase you want water to separate out where you can see it rather than emulsify invisibly.

On intervals, check your manual rather than a generic number, because the industrial pumps and the small direct-drive pumps are not on the same schedule. What is consistent is the break-in change: most AR pumps want their first oil change early, around 50 hours, because break-in puts metal into the oil. After that it is typically a few hundred hours.

If the machine runs seasonally and never reaches the interval, change it annually anyway. Oil absorbs moisture sitting still.

The oil is also your diagnostic. Look at it through the sight glass before every start:

Milky oil is the one people get wrong. Changing the oil and carrying on just gets you milky oil again in a week, and meanwhile water is in your bearings.

5. Winterize properly

Water expands about nine percent when it freezes, and a pump head is a sealed cavity with nowhere for that to go. Brass cracks and ceramic plungers shatter. You find out in the spring.

Draining is not sufficient on its own, because water stays in the valve pockets and behind the seals however you tip it. Feed pump saver into the inlet and run the pump until you see it come out the discharge. That is your confirmation. Then cap the ports so the film does not dry out over the winter.

Do not use automotive antifreeze. Ethylene glycol is toxic and whatever is in the pump in October comes out of the nozzle in April. Propylene glycol RV antifreeze is the acceptable substitute if pump saver is not available.

Triplex pump parts

Use pump-specific seals, valves and oil rather than generic substitutes. The seal compounds are matched to temperature and chemistry, and a generic o-ring that looks identical may not be. Keep a seal kit on the shelf if the machine is on a schedule you cannot miss.

The five habits, in short

1. Water first, nozzle last
2. Shut it off instead of idling
3. Clean filter, short hose, tap wide open
4. Look at the oil before every start
5. Pump saver before the first freeze

Browse pressure washer pumps, or send us your model number and we will point you at the right seal kit and oil. Contact us here.