How to Avoid Coolant Leak After Water Pump Replacement

Car water pump repair- Things to Consider When Replacing Water Pumps

Are you noticing the new water pump leaking that you just installed? Its likely a coolant leak after water pump replacement. Water pumps generally get changed due to a noise possibly a bearing failure a leak or possibly a seal failure. You’re probably wonder:

  • Why is my new water pump leaking? How long will a water pump last after it starts leaking?
  • Is it just water pump normal wear and tear?

Are you frustrated with the frequent coolant leaks even after installing the water pump more than once? Well, you have every right to be. Coolant may leak due to various reasons. Among them, the wrong installation of a new water pump is one. Don’t worry. Now you are in the right hands. I’d be just as frustrated as you if the new water pump is leaking. Let’s get it resolved.

Read: ACDelco Water Pump details

ACDelco 252-845 Professional Water Pump Kit
ACDelco 252-845 Professional Water Pump Kit

In this article, we are going to state the various reasons for coolant leaks along with the replacement of the water pump. We will also try to provide some remedies so that you can leave the stress. You know what to do. Stay with us till the end and you will know everything you need to know.

What is a Coolant?

Before jumping in to understand why the new water pump is leaking, you may want to know what a coolant is in order to have a better idea about the problem. The mixture of glycol and water is generally called a coolant. It can be both ethylene and propylene glycol. The color of the coolant can be different depending on the type you want to buy. It may be green, blue, and also maybe pink.

what is coolant in a car

Anyway, what is the job of the coolant? The name indicates what it does. The function of the coolant is to keep the engine cool. In other words, to keep the engine safe from any possible boiling or freezing. As in almost all cases, the coolant is liquid, it is easy for the coolant to absorb heat and protect the engine from boiling.

However, if due to any reason, the coolant fails to do its job properly, you are in trouble. Although you will not notice symptoms right away, you will fall in danger for sure. And it is more dangerous as you won’t know what is happening to your car and may confuse the symptoms with radiator failure. Therefore, you have to use the right coolant and keep an eye on its functioning.

5 Most Common Reasons for Coolant Leak After Water Pump Replacement

First things first. How do you know that the leak you have found is a coolant leak? The first and most common symptom of a leak is if you see any fluid on the floor while the vehicle is parked. You can also know about a coolant leak by noticing any significant change in the temperature gauge.

If you see these symptoms, you have to make sure they are because of a coolant leak. You can do that by filling the expansion tank and afterward checking the coolant level. If fluid drops then you will know that you have a coolant leak. Now let’s head to the reasons why you may have a leak.

1. Leaked Radiator Cap

The radiator cap has a huge task to do. You may think this tiny piece of material does not have a very big role to play. But you are wrong if you think so. As the radiator faces extreme pressure all the time, the cap ensures that the radiator remains sealed.

Thus, the coolant will not flow away. The cap may deteriorate as time passes and the spring may also start wearing out. So, you have to keep an eye on the radiator cap to make sure everything runs fine.

2. The radiator has a hole

Having a hole in the radiator or having a damaged radiator is one of the key reasons for a coolant leak. The radiator is a very efficient part of your vehicle’s engine. It has to take a toll of loads to serve its purpose. By doing its work, with time the tubes may become weaker to perform their functions.

As a result, it will be possible that the tubes will get debris or sediment inside. And eventually, it will cause a leak. Sometimes, the hoses that are connected to a radiator can be also responsible for such leaks. With time, these hoses can become hard and thus will not seal well. For this reason, where the hoses connect the radiator, all the places near the connection become exposed to leaks.

3. Blown head gasket

The basic purpose the head gasket serves is to keep the coolant and engine oil separate. But if the head gasket fails to perform its job or in other words gets blown, you are in serious trouble. The head gasket may get blown over time as it faces both high and low pressure from the engine. You won’t even know if that happens for quite a while.

However, the moment you are sure of a blown head gasket, you have to take immediate steps to address the issue. As the head gasket is not up for the task, there won’t be anything to separate the coolant from engine oil. As a result, the engine cooling feature won’t work. You know very well where all that leads to.

4. Problematic Expansion tank

The coolant may leak from a faulty expansion tank too! The expansion tank ensures the supply of coolant to the radiator. It is a plastic container that resides right beside the engine. Plastic is not that durable, we all know that. Due to temperature changes or other factors, the expansion tank may lose its shape.

If that happens, it will no longer be able to perform its functions. As a result, the coolant will leak.

5. Failed Water Pump

The water pump resides basically close to the drive belts, on the engine’s lower part. It usually connects the radiator’s lower hose. The job of a water pump is to circulate the coolant throughout the overall cooling system. Thus, it plays a big role in the cooling department.

If the connection becomes loose or the hose wears out with time, it won’t be able to perform properly any longer. Thus, it will cause a leak and other problems to the engine.

How to avoid coolant leak After Water Pump Replacement

The coolant leak is uneconomic and problematic for the engine at the same time. If you can find out the sources of the coolant leak problem, your job is half done. The rest of the job is to sort out the problems. You have to pay close attention to find out any symptom that lead to a coolant leak. Then, you have to take care of the situation. 

If you have a faulty radiator or leaked radiator cap, you may change them to get rid of the problem. In the case of the blown head gasket, you have to replace it too, with the right one. And in the case of water pump replacement, you have to be extra careful. Replacing the water pump with a proper alternative only won’t do the job. You have to make sure that you have followed the right ways to install the water pump as it is a very difficult process. 

However, the preventive measures are always there for you to follow. You can do regular maintenance on your vehicle to get a better idea of what is happening. Changing the coolant before the expiry date is also a good idea to keep the vehicle running better. 

Coolant leak After Water pump replacement

Replacing the old water pump with a new one may become necessary. You may need the replacement either to replace a very old one or to change the faulty water pump. Regardless of the need, you may head into further problems as replacing the water pump is a very technical job.  Check stator cover as well and if so replace the gasket around the stator cover. 

Most probably, your vehicle uses a timing belt. In that case, there is a big chance that the water pump is driven by the timing belt too. Thus, it will be very tricky to remove the water pump in order to replace it as you will have to replace the timing components too. If you don’t do it right, the water pump won’t be able to do its job. Eventually, you will not be able to stop the leaks. 

Fixing tiny coolant leak in overflow hose caused by gas tank

How to avoid coolant leak After water pump replacement

As this is a very difficult job to do, it is better to leave this to experts if you are a beginner. However, if you still want to go for it, here are some of the don’ts to help you out. If you follow these advices along with the basic guideline, you are going to do it right this time. 

  • Don’t apply any sealant to seal
  • Don’t use an old or too cold coolant
  • Don’t forget to vent the cooling system properly
  • “Do” use new coolant on a regular basis


Why is my new water pump leaking? 

If your new water pump is leaking, it’s likely due to the coolant or incorrect installation. Changing the water pump is a very tricky and difficult process. We advise you not to do it yourself if you are not acquainted with the parts properly. If you do that by ignoring our advice and do something wrong, the outcome will be terrible. So, even the new water pumps may leak if you do not do the installation properly and keep the hoses loose during installation. 

Can coolant Start Leaking From a New water pump? 

Yes, coolant may be leaking from your new water pump. The water pump’s job is to provide coolant throughout the engine. Thus, coolant has to flow within the water pump. Over time, the water pump may become unable to serve its purpose. In that case, the coolant will leak from the water pump if there is any hole or corrosion in it. 

How do you stop a water pump from leaking coolant? 

The appropriate answer to this question is to install the water pump properly. The installation of a water pump is not a beginner’s thing. You should not think about it if you are a beginner. If you really want to stop the water pump from leaking coolant, you have to make sure the water pump is properly installed. In the case of an old water pump, if it is possible to service it, do so. 

How long can you drive with a bad water pump? 

You should stop driving as soon as you find out the water pump has become bad. Because driving in that situation won’t affect the water pump only, it will significantly affect some other parts of the cooling system too. However, if you still want to drive in the worst-case scenario, you may be able to cross 5 to 20 miles depending on the damage. 

Do you have to drain the coolant when changing a water pump? 

Yes, you have to. The water pump is situated in a very tricky place. To avoid any kind of spillage while removing the water pump for replacement, you have to drain the coolant from it. 

Why is my coolant leaking so fast? 

There are various reasons for coolant leaking. If your car has multiple reasons for leaking coolant, the coolant will leak faster than that of a single reason. It is pretty much logical. So, if your vehicle is drying out with an instance, there may be several damages inside the cooling system. Go to the mechanics immediately to sort out the problem. 

Coolant Leak After Water Pump Replacement

How about why a relatively new water pump failed?

Water pumps may fail due to contamination and corrosion caused by lack of proper maintenance or servicing of the cooling system failed to flush the cooling system.

When the water pump or other system components are replaced can leave excessive contamination and lead to a failure or a repeat failure.

When replacing a water pump or other system components it is critical to flush the cooling system and clean the coolant reservoir.

Power flush equipment or thermal cycling of the cooling system with clean water three times are good ways to flush the cooling system.

The most effective method is to use a coolant exchanger. Coolant should also be changed at regular intervals according to the manufacturer’s recommendations.

Coolant should be checked for concentration at regular intervals as well we would recommend using a refractometer.

After prolonged periods of use the coolant can breakdown become corrosive or lose its rust preventative properties.

Coolant test strips may also be available for determining coolants acidity level.

Some additional tips when it comes to coolant are mix concentrated coolant to the approved mixture traditionally 50 percent coolant 50 percent deionized water.

Use clean drinking water as impurities in the water can cause a reaction to the coolant and harm the system. Again deionized water is recommended.

Keep the system full eliminate. All air trapped air causes pour heater core performance and can potentially cause premature failure.

Maintain correct system pressure, as it increases the boiling point of the coolant. Source

Do not use any non-proved flush agents.

water pump leak quick fix

Image Source


To avoid Coolant leaking after replacing the water pump follow these tips

  1. Clean all sealing surfaces
  2. Never strike the water pump shaft as it can cause damage to the new water pump to tighten and torque all bolts according to the manufacturer’s specifications.
  3. Adjust belts to proper tension according to the manufacturer’s specifications.
  4. With the new water pump installed turn the hub by hand and check for rotation.
  5. After installation, pressure test the system for leaks.
  6. Check for sufficient fan blade clearance between the blade and radiator shroud.
  7. Use sealant tabs only if recommended some sealant tabs may restrict coolant flow through the passages of some cooling systems.


There are several other components that should be inspected when replacing the water pump-

  1. Check the fan blades for cracks bends breaks loose rivets are damaged also make sure the fan blade does not have any run-out.
  2. Always check the fan clutch for where leaking silicone fluid bent or missing blades and play at the fan tip. There should be no more than 250 thousands of an inch of play check for worn or broken engine mounts and replace if necessary.
  3. Inspect for any damage to the radiator including the radiator shroud and mounts.
  4. Pressure test the radiator cap for proper holding pressure.
  5. Inspect the thermostat and thermostat housing replace if necessary.
  6. Check belts and hoses for any glazing cracking swelling leakage or damage.
  7. Check the belt tensioner and pulleys.
  8. Check the overflow reservoir/hose for cracks or damage.
  9. Check the drain plugs and the hoses for starters. Source

——————-According to CostHelper, water pump replacement averages $300 to $750, depending on the make and model and labor costs. The water pump itself may only cost $50 to $100, but labor can run between $200 and $450, depending on the difficulty level of reaching the pump. Source › 

Don’t forget to flush the cooling system before you replace the water pump.

Use the right tools for the job and check all other components that could add unnecessary strain on the water pump.

And your new water pump will not fail prematurely.


It is never a good experience to see the coolant leaking after a water pump replacement. It is even more painful when your new water pump is leaking. The faulty and damaged water pump is one of the main reasons for a coolant leak. In order to address this issue, you have to replace it with a new one. But even after the replacement, if you see the same issue, it will be frustrating for you.  We always tell to leave the trickier services for the experts. Replacing a water pump is a very tricky job. However, if you follow our tips and stick to the basic guideline, you will have a better chance of success. We have tried our best to quench your thirst for this topic as much as possible.

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