Should You Replace Thermostat When Replacing Water Pump?

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When a critical component fails in your car, it is important to carefully inspect surrounding components to see if they need to be replaced as well. The water pump circulates coolants across the engine blocks to keep the engine’s operational temperature at the right levels.

Several factors can affect the water pump and cause it to fail, and when this happens, some other components that surround the water pump are at risk – this includes the thermostat. But should you replace thermostat when replacing water pump?

Yes, it’s a great idea to change the thermostat when changing the water pump, because the failed water pump may have damaged the thermostat too. However, if your mechanic insists that the thermostat is still working fine and doesn’t need a change, that’s pretty cool.

Relationship Between the Thermostat and Water Pump

The thermostat and water pump actually work hand in hand. When the engine heats up, it forces the thermostat to open up so that coolant from the water pump would get into the engine to cool it down.

So, if the thermostat doesn’t open up, coolant flows into the engine when it heats up, and if the water pump isn’t working, even if the thermostat opens up, nothing would flow into the engine.

Either of these scenarios can cause the engine to overheat, and possibly damage several parts of the engine, leaving you with an expensive repair to deal with – you may even need to replace the engine, entirely.

A bad thermostat would affect the water pump and vice versa. Hence, replacing the two at the same time is pretty advisable, especially if it took you long to respond to the signs you were getting for a failing water pump/thermostat.

Should You Replace Thermostat When Replacing Water Pump?

It’s not compulsory to replace the two at the same time, but there are situations where you need to do that. If the water pump just got spoiled and you want to fix it right away, there’s no need to change the thermostat too, because, apparently, the failed water pump hasn’t affected the thermostat yet.

In contrast, if the water pump failed and it took you long to go in for a replacement, then it is best to replace the thermostat too; else, you may return to the mechanic shop quite too sooner to change only the thermostat, which would cost you additional “Labor” charge.

However, if you do the thermostat change at the same time you’re changing the water pump, you’d only pay a single labor cost for the two. A thermostat is cheap; it’s not up to $100 in any store.


So, should thermostat be replaced when replacing water pump? It depends on certain factors. If the water pump hasn’t been bad for a long time, you should just get the pump changed and leave the thermostat.

But, it is best if you change the two at the same time – just as it’s advisable to change oil filters at each oil change interval. It’s not compulsory, but advisable so you would get a long time before driving in for any repair or replacement.

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