Coolant Leaking After Replacing Water Pump

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

Water pumps generally get changed due to a noise possibly a bearing failure a leak or possibly a seal failure. after changing the new water pump some questions arise?

Why is my new water pump leaking? How long will a water pump last after it starts leaking?

Have you ever wondered if it’s just normal wear or if something else caused the failure?

Read: Best ACDelco Water Pump Review

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

Coolant Leaking After Replacing Water Pump

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.


Cavitation is the process where a bubble in a liquid produces a shock wave when it rapidly collapses.

The shock wave is strong enough to damage the cooling system components including the water pump.

The bubbles are usually caused by the pressure of a liquid falling below its vapor pressure.

Cavitation is most likely at the impeller blades of the water pump where flow rates and turbulence may be high.

This shock wave can cause a vibration and noise as well as pitting erosion and additional wear.

water pump leak quick fix

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The pitting accelerates erosion because it increases the turbulence of the fluid flow which creates more cavitation and eventually could lead to water pump failure.

Water pump seals are a critical component in the cooling system. the seal phases are in sliding contact and subjected to temperature pressure and speed changes.

Coolant is a major factor on seal longevity and is not necessarily designed to lubricate the seal.

Contaminated coolant depleted coolant and poor water quality can result in corrosion and seal damage.

Filming on the seal can be caused by low coolant cavitation hard water corrosion and coolant additives which also can cause the seal to fail.

Stop leaks are also hard on seals.

Quality coolant and water are critical to water pump operation.

Water quality varies greatly in different areas. Unclean water also leaves mineral deposits in the cooling system which can reduce coolant flow.

Engine coolant comes in various colors and formulations ranging from conventional green coolants to a variety of long life coolants that may be orange, red gold or blue.

The color is mainly a dye but the chemistry of the coolant is different.

Always check the manufacturer’s service information for the correct coolant for the vehicle being serviced.

When installing a new water pump there are a few additional tips that help ensure a proper repair. 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 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.

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Dencan Brain
I, Dencan Brain BOŽIDAR, call myself a Torque master. I've always been fascinated with cars and tools accessories. You can call me gearheads or petrolheads. I recently started a blog about welding gear.I am also a DIY welding enthusiast because it is affordable for any household work. Follow me on Facebook, Twitter, Instagram, LinkedIn and tumblr.
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