Why Does My Pool Pump Overheat and Shut Off?

The pump is literally the heart of the pool, and like our own hearts, it’s really important to make sure it is always in good working condition. One of the most common problems we run into is overheating, following by the pump shutting off. I had this problem a few years ago, and here’s how I found the problem and fixed it.

Your pump is shutting off as part of its safety mechanism to prevent it from catching fire from overheating. Some causes for overheating are:

  • Your pool pump is running dry.
  • Friction from impeller obstructions or corroded bearings.
  • Lack of airflow.
  • Electrical problems.
  • Bad flow dynamics in pipes.

The good news is that your safety mechanism, which is a thermal disconnect is working. But that doesn’t help us with what’s causing the pump to overheat. Let’s go through each of the potential problems, and find out how we can diagnose and fix each one next.

How Hot Should A Swiming Pool Pump Be?

All swimming pool pumps will generate a fair amount of heat. But the fact that your pump is switching off means that it is running too hot.

A swimming pool pump should be running 115 and 200 degrees Fahrenheit. Anything higher than 200 degrees will start to damage the pump. It should be hot to the touch, but not searing hot. You should be able to touch the pump for at least a few seconds.

Leaving your pump running too hot, even only slightly, can drastically reduce the life span of your pump. If you keep your pool pump running efficiently and at the right temperature, it could last anywhere from 8 to 12 years.

Running Your Pump Dry can Cause Overheating

Leaving your pump running dry for an extended period of time will cause the impeller to turn at a very high speed. The friction from this will cause the impeller and the housing around it to overheat. If there is any water left inside, this will be superheated into steam and melt plastic components in the pump. If the thermal disconnect is working, it will turn the pump off before the damage gets this far, but we still have to fix the problem.

What causes my pump to lose prime and run dry?

  • Air leaks in the line, fittings, skimmer, or hose.
  • The water level is too low and your pump is sucking air through the skimmer.
  • Leaves and debris blocking up the skimmer basket.

Here’s an article I wrote: What Happens If My Pool Pump Runs Dry? It explains in detail the causes and fixes for pumps running dry.

Overheating Caused by Friction

Your swimming pool pump consists of many moving parts, all of them causing friction and eventually some heat. While some heat or normal and managed by the pumps fan and heat sinks, anything too hot to touch for a few seconds could pose a problem.

Friction caused by corroded bearings

The pool pump shaft is held in place by steel bearings. If these bearings start to corrode and fail, they will start to produce a lot of heat. The grease inside the bearings will dry out and rust will start to form. Where there was a free and lubricated movement in the bearing, there is now steel on steel generating heat, made worse by rust particles.

You will be able to tell that the bearings have failed by the type of sound coming from the pump when it is running. The bearings will produce a high pitched squeal. If your pump is making this sound, take it in for a service immediately and tell the repairman that you think it is the bearings.

How to avoid corroded bearings

The main cause of bearing corrosion is leaking water. If you notice your pump leaking even a small amount of water, don’t ignore it! Have your pump services. Fixing a leak is usually cheap and a stitch in time saves nine.

Lack of Airflow Can Cause You Pool Pump to Overheat

Fan obstructed and unable to cool the pump.

This will be obvious and straight forward to fix. On the far end of the pump, there should be a removable cover. First, switch off the pump, then slide this cover off. Make sure that the fan spins freely and there is nothing inside causing an obstruction preventing the fan from cooling the pump.

There is not enough ventilation for the fan to draw cool air.

The pump needs to draw cool air through the fan. If the pump is installed inside a small enclosure, it will simply be recycling the hot air. The pump should be under some sort of cover to protect it from the elements, but it should be very well ventilated.

If there is not enough ventilation, your pump will start to overheat and this will either reduce the service life of the pump and in very bad situations, can damage your pump. To eliminate this problem completely, avoid installing your pump inside any sort of room or other enclosure.

Where should I install my pool pump?

All you really need is cover from sun and rain, with good airflow.

Many professionals install the pump underneath a balcony, under a roof overhang against a wall or erect a simple roof structure over the pump. These all protect the pump and equipment from the elements while providing maximum airflow around the pump.

Bad Flow in Your Pool Lines.

The water going through your system needs to flow smoothly. Water flows best in a straight line, and every time you add a bend, you create extra pressure, and that affects the flow negatively.

Ideally, your lines from and to the pool should be as straight as possible, with only a bend at the skimmer, pump, and return jet. For some reason, this is often overlooked by pool installers.

Too many bends in the line will add a lot of load on your pump as it has to work extra hard to maintain the flow rate. This could drastically increase the pumps operating temperature and can cause the pump to overheat in the same way that an over-revving engine in your car would.

Unfortunately, the only way to fix this problem correctly is to have someone dig up your old lines and reinstall new lines correctly.

Electrical Problems Can Cause Overheating too.

Is the pump wired correctly?

Look at the user manual of your pump. If you have lost it, simply go online and Google the make and model of your pump. Most manufacturers will have an online manual available. look for a wiring diagram and compare it to the wiring of your pump to make sure it was installed correctly.

Is the supply voltage correct?

Make sure the voltage to the motor is within +10% and -10% of the specifications of the motor. If it is above 10% then you will need to call the local power company and explain to them so that they can come out and fix it. If it is lower than 10% then make sure you have the right wire size running from the distribution box to the pump.

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