Within this page, we will discuss symptoms of a worn or bad Vw water pump. Common statements and questions regarding Vw water pumps are addressed and explained. What are the symptoms of a defective water pump? Did you recently install a new water pump and are now experiencing problems? What causes a Vw water pump to fail early?

We've read some comments asserting that water pumps don't get weak, they catastrophically fail. Our decades of specialized Audi Vw repair service has shown that like most mechanical parts, the water pump warns you when it needs attention. The internal bearing and seals of a Vw water pump can weaken and is the primary reason why a water pump eventually fails. The typical driver isn't always alert to what is going on under the hood and may be unaware of the water pump's health. However, an experienced mechanic who is familiar with Vw or Vw engines can recognize the early signs of a weakening water pump. The most common symptom being a water pump leak. When unchecked, a leaking Vw water pump can eventually create a humming noise and possible engine overheating. In Blauparts® own Audi Vw repair facility, experience has shown the most common causes of water pump failure to be: 1) age and/or high mileage and 2) a neglected coolant system that was not restored to the original factory intended condition during water pump replacement.

If it has been determined (not assumed) that your Vw water pump is leaking, you should not continue driving the car. Continued driving with a leaking water pump (for an extended period of time) can be catastrophic. There is the possibility that the internal Vw water pump bearing will develop excessive play, causing a misalignment of the water pump pulley, allowing the timing belt to rub against other components, thus resulting in timing belt failure and engine damage (see image above). The Vw water pump impeller may also rub against the inside of the engine block, causing fragments and debris to contaminate the cooling system. If this debris or sediment is not thoroughly flushed from the cooling system when installing a new water pump it will eventually lead to premature Vw water pump failure.

Vw Coolant System Contamination Image 1) Original water pump removed from a Vw 2.7T with approximately 80,000 miles. This pump was not leaking. Note the normal discoloration of the aluminum casting. This is the result of minimum coolant contamination for this type of mileage. Blauparts® Vw water pump replacement 'Service Bulletin' pdf. Image 2) Water pump removed from a Vw 2.7T with less than 3,000 miles due to leaking. It was wrongly assumed that it was a manufacturer defect. However, the evidence revealed that the leak was caused by coolant contamination. Note the abnormal black discoloration of the aluminum casting. The cause was a result of an additive (likely a flushing agent) containing muriatic acid/other acids being used (before or after the water pump replacement). Acids left in the coolant system ate away at the internal seals and caused premature water pump failure.

Do you want your Vw water pump to last 60,000 to 90,000? Then, it is important to re-create the engine condition as it was when it left the factory. You can not be lazy when it comes to the water pump and timing belt replacement! Cutting corners now adds time, labor, and money later.

It is the installers responsibility to take the necessary time to thoroughly flush the cooling system. It has been noted that due to time constraints, inconvenience, and profit, many individuals, mechanics, and repair shops do not take the extra time needed to thoroughly flush the entire cooling system prior to the installation of a new Vw water pump. Just draining the cooling system and refilling it is not enough! Thoroughly flushing the coolant involves the engine block, radiator, heater core, and hoses.

Premature water pump failure (bearings and seals) can occur if you don't take the time to flush the entire cooling system and it's related components. Often when problems arise, such as a coolant leak, the new Vw water pump is blamed as the cause when if fact the opposite is true. It's usually because the installer has neglected to follow this important step.

Flushing The Vw Cooling System

It is imperative that the Vw cooling system be thoroughly flushed of all accumulated silt and sediment buildup. All aftermarket cooling system additives, or stop leak products that may have been added to the cooling system (past or preset) should be completely flushed! Thoroughly flushing the coolant involves the engine block, radiator, heater core, and hoses.

Only use tap water to flush the entire cooling system. Do NOT use cooling system flush products. Many of these agents contain muriatic and/or other acids. Remnants of these acids left in the cooling system can cause your new Vw water pump to prematurely fail (see Image 2).

Filling The Vw Cooling System

Use only Audi Vw G12 antifreeze coolant which was included in your timing belt kit (G11 pre 1997). These bottles contain coolant that is concentrated. You must dilute the coolant. Mix 50% coolant and 50% DISTILLED water. DO NOT mix normal tap water with new coolant. Tap water varies in PH and mineral content and depending on these factors, can adversely effect your new water pump and cooling components. IMPORTANT: Read the warnings on the antifreeze coolant bottle regarding improper use being harmful or fatal. Click here for our detailed page covering everything about Vw coolant / Vw antifreeze.

TIP: When topping off your cooling system, always use the factory approved Vw coolant and appropriate mixture ratios! Make sure that your local quick lube or mechanic isn't adding or topping off your system with incorrect coolant. Mixing factory approved coolant with any other coolant will cause an adverse chemical reaction with the existing coolant and contaminates the cooling system, thus affecting the longevity of the Vw water pump.

Age and/or high mileage is the most common cause of water pump leaks.

Don't jump to conclusions. You can't assume that a puddle of coolant under the car is due to a leaking water pump. An experienced A.S.E. certified mechanic that is familiar with your particular model can best inspect and verify where a coolant leak is coming from.

The diagnostic starting point involves removing the splash pan. This will enable you to see where the coolant is pooling. The passenger side of the engine compartment, the center front of the engine, or the drivers side? Common coolant leaks originate from coolant hoses and the expansion tank. The expansion tank often becomes brittle and leaks below it's location (in front of the drivers side wheel on most models).

When a Vw water pump is leaking, you'll usually find a trail of coolant from the water pump area down to the lowest point of the engine (depending of model). Removing the engine covers and visually inspecting the water pump is necessary. On some engines such as the 2.8L and 2.7L, coolant may have pooled onto the self of the flat oil pan surface.

a Vw water pump usually leaks from the following areas:

1. Vw Water Pump Shaft Bearing or Seals

Incorrect Use Of Water Pump Sealing Agents Image 3) Water pump removed from a Vw 3.0L with less than 5,000 miles due to leaking. The customer wrongly assumed that it was a manufacturer defect. However, the evidence revealed that the leak was caused both by the use of RTV gasket material and coolant contamination. Using RTV material can cause the gasket to slip, resulting in misalignment during installation, producing a coolant leak. Sealing agents vary in composition and intended usage. When used in conjunction with composite paper gaskets, they negatively affect the gasket's ability to properly compress and perform the sealing function, rendering them ineffective. The abnormal coloration and thin film on the aluminum casting is evidence of acidic coolant contamination. See Crucial Vw Coolant Flush and Fill Information.

Age and/or high mileage is the most common cause of internal bearing and seals weakening or failing. Bad water pump bearings and seals usually cause a leak from the water pump shaft. Premature failure is typically due to contaminated antifreeze. Contamination caused by not thoroughly flushing coolant system, using flushing agents, containing damaging acids using or mixing incorrect fluid with factory approved.

See Crucial Vw Coolant Flush and Fill Information and Blauparts® Vw Water Pump Replacement 'Service Bulletin' pdf.

2. Vw Water Pump Gasket Mating Areas

The key to a factory quality seal is in the preparation of the surface area. Take the extra time to properly clean the Vw water pump gasket and thermostat o-ring surfaces thoroughly. These surfaces should be free of all old gasket material and corrosion build up before installing your new Vw water pump and thermostat. To achieve the optimal just like new surface, it's usually necessary to use a medium grit scotch brite pad and/or angle die grinder with a medium grit scotch brite conditioning pad (see the video below). When the water pump mounting surfaces are thoroughly cleaned and smooth, gasket sealing agents are not needed!

Some installers have used sealing compounds which can significantly reduce the sealing function of the Vw water pump gasket. It is important to note that no sealing compounds were used when mating the water pump to the engine block from the factory. The factory Robert Bentley manual makes no reference to using sealing compounds during water pump replacement. It is important to pay attention to and follow the manufactures installation instructions. Sealing agents (RTV Form-a-Gasket silicones, aerosol adhesives or sealants) should NOT be used!

Premature leaking from the Vw water pump gasket mating area is almost always due to improper alignment during installation, mating surfaces not being prepared properly, or a sealing agent being used. Sealing agents (RTV Form-a-Gasket silicones, aerosol adhesives or sealants) vary in composition and intended usage. When used in conjunction with composite paper gaskets, they negatively affect the gasket's ability to properly compress and perform the sealing function, rendering them ineffective (see image 3).

Although uncommon, the wrong type of coolant can eat away at the gasket and eventually cause a leak. Double check all Vw water pump mounting bolts for tightness. A loose or missing water pump or thermostat housing bolt can also result in a leak.

How To Properly Prepare The Vw Water Pump Gasket Mating Surface Video

Please see the 'Vw Water Pump Service Bulletin' for some important DOs and DONTs of Vw water pump replacement.

Appropriate gel like gasket sealing agents should only be used when there is severe pitting of the engine block surface and an even or smooth water pump mounting surface cannot be achieved. Not because you're cutting corners and don't want to take the time to clean the surfaces properly.

An Audi Allroad 2.7L Turbo engine is shown in this video. Regarding 1.8L engines, the same theories illustrated in this video apply. Installers need to take the extra time to correctly prepare the water pump o-ring area to ensure a factory quality seal. Be sure to clean all old o-ring material, built-up residue, loose debris, and prepare the surface using a medium grit scotch brite pad. Experience has shown that when not properly prepared the new 1.8L water pump o-ring may not seal evenly, resulting in possible hair line coolant leaks. In addition, sealing agents (RTV Form-a-Gasket silicone, aerosol adhesives or sealants) should not be used. We reference a 1.8L water pump in the video which illustrates the improper use of such RTV material. The example shows how stray RTV can let loose and clog internal components such as the heater core.

3. Vw Water Pump 'Weep Plug' Hole

Age and/or high mileage is the most common cause of a weep plug hole leak.

Water pumps are inspected and air pressure tested at the factory for any leaks. Per the manufacturer, all new water pumps have a break in period. Shortly after startup, it is not uncommon for a new water pump to have slight seepage or coolant discharge coming from this hole below the water pump pulley. This is because the unique seal material in a new water pump is designed to 'bed in' as the impeller shaft spins. Slight weeping or dampness from or around the discharge 'weep plug' or cap is allowable for at least 100 miles after installation and should not be attributed to a defective water pump.

However, in extreme cold climates (below freezing), it's important that the correct coolant mixture ratios be maintained. If the coolant ratio is incorrect, it can cause weakening of the machined weep hole tolerances causing a leak.

Users post videos of engine noises (whine, humming, squealing). Where is it coming from, they ask? Don't assume that the noise is coming from the the water pump, unless it has been leaking for some time. The possibility is very remote that the water pump is making the noise if it isn't leaking.

Many possibilities can account for front engine noises such as: Alternator bearing, AC compressor clutch bearing, viscous fan clutch bearing, serpentine belt tensioner(s), serpentine idler wheel, power steering pump, any other belt driven component, or lastly the timing belt tensioner idlers. A simple test is to remove the serpentine belt (which drives many of these components). If the noise goes away, it is a serpentine related component. If the noise persists, then it may be something behind your Vw's timing belt cover.

It is normal for a new Vw water pump to make a light hum during the manufacturer's break-in period. Some aftermarket manufacturers that use cheaper internal bearings may make a slightly louder drone. Blauparts® only supplies the highest quality Vw water pumps that are manufactured using the OEM internal bearings and seals. Another cause for this type of noise can be an over tensioned timing belt. Incorrect timing belt tension puts additional stress on the internal water pump bearings, causing a droning noise.

It is very rare for a Vw water pump to make a rough grinding bearing noise. However, driving with a leaking water pump for an extended period of time can produce this type of Vw water pump noise. At this point, the internal bearings have developed excessive play and the seals have already failed. Continued driving of the car could be catastrophic.

Some drivers experience random overheating issues and wonder if this is caused by the Vw water pump. Intermediate or random overheating is usually due to an obstruction in the cooling system or a sticky, malfunctioning thermostat. We recommend looking at the thermostat first.

Has the car been overheated either by you or the previous owner? Depending on the severity or how long it was driven in an overheated state (one instance will do it), your cylinder heads (possible warping) and head gasket (weakening) will be affected. Warped cylinder heads or weak head gaskets intermediately begin to seal and unseal, discharging cylinder compression into the cooling system and disrupting or preventing the flow of coolant. This is usually what can cause overheating, not the Vw water pump.

Overheating due to a water pump is very rare. There is the possibility that the Vw water pump impeller has begun to separate or break loose from the shaft. This can result in insufficient engine coolant flow and possible overheating, due to the impeller's inability to turn the same RPMs as the engine. Remove and inspect the water pump to see if the impeller has spun on the shaft. This was known to happen on earlier (pre 2000) models. See the Vw water pump plastic impeller controversy. Expand your knowledge regarding this debate by watching our video.