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The Toyota Water Pump Issue And Overheating

Hi there, I’m Saul Reisman here at Saul’s Autotek, and today we’re going to talk to you a little bit about overheating concerns, and the number one reason that we see them come into our leading Denver auto repair shop in Greenwood Village.

In Colorado, we see very strong heating and cooling cycles with vehicles. As a result, overheats are a very, very common issue. Even in the wintertime when we might not think they’re a big deal, driving in the mountains can easily put enough strain on it for a vehicle to show its weakest points. Most Toyota vehicles, unfortunately, will see water pump failure during their life. We don’t know what the correlation is, but all Toyota vehicles that we service here have commonality for water pump failures, whether it’s the 1ZZ-FE, the 2ZZ-FE or even the more modern V6s and V8s, we seem to see a pretty common problem with these Toyota water pumps.

Now, a water pump’s a pretty basic design, so we kept this last one off this Toyota Sienna, ( We are the top Denver experts in repairing the Toyota Sienna) we just serviced so we can figure out what the most common issue is, why they fail and how we can best prepare you for it. What we found is that the water pump, which in this case is belt-driven, uses an external drive from the belt in order to actually rotate the pulley inside it. On the front of the pump itself, there would be mounted these four bolts a pulley, which is driven by the rubber serpentine belt for the vehicle, and that allows this to rotate. When this rotates, it, in turn, spins the impeller inside the water pump housing, which then allows it to circulate water through the coolant jackets.

Unfortunately, the most common issue that we’ve seen is that the water pumps themselves actually don’t lose efficiency or degrade, but the bearing in the middle of this pump where it rotates, begins to fail. In the case of this water pump, it gave us a pretty fantastic failure, and we’re happy to be able to show it to you. Most of these water pumps when they come in, are perfectly vein-driven, and the speed of one side matches the other. This one was completely sheared apart. It had actually corroded the center of it and had broken off the center of the bearing itself, so even though this bearing was spinning externally being driven by the belt, and everything from the outside of it looked perfectly normal, this impeller was not spinning whatsoever, and can just freewheel with no rotation. So even though the outside of this pump could be spinning to it, the inside wasn’t actually circulating coolant through the vehicle.

Now, the downside of this failure is there’s nothing visible from the outside of the vehicle. So, if it’s something that you just saw your temp gauge going up, or you saw the steam under the hood so you know it’s overheating, and you look through it, you might not see the problem. It’s even possible that a mechanic that’s just doing a quick visual once-over might not see this issue at all, might see that the vehicle’s full of coolant, everything looks good, the pump’s spinning, and not see the problem.

At Saul’s Autotek, we try and go above and beyond from the diagnostic standpoint, to make sure you get the right diagnostic every time, the first time.

In this case, we use an infrared temperature thermometer to measure the temperature going into and out of the pump, through these coolant jackets, while the engine’s running. That way, we can measure the temperature differential across that drop, do a volumetric efficiency integral with calculus to determine is it actually dropping the temperature the amount that it should for the volume of coolant and the speed of this impeller turning in. We were able to see immediately that the temperature drop was minimal. There’s no way this impeller was doing its job, and the vehicle had a failed water pump. So without ripping it apart, without tearing it to pieces, and with simply two or three basic tools, we were able to confirm this water pump failure, diagnose it accurately, get the repair done and get the owner on their way.

If you’ve got a concern about yours, or if you’ve got a Toyota that’s seen water pump failure issues, come and see us here at Saul’s Autotek. We’d be happy to keep you cool too.

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About the Author

Picture of Saul Reisman

Saul Reisman

Saul Reisman has been helping the residents of the Centennial State with their automotive needs for over ten years now. He finished his Associate Degree in Physics at the Community College of Denver. Saul is an active member of the Specialty Equipment Market Association and a board member of the Young Executives Network. He undergoes constant educational training through GMC, MOPAR, Ford, Snap-On, Borg-Warner, and Ozark Automotive, with an emphasis on diagnosis, repair, and improvement.

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