When nearing a timing belt and VW water pump replacement (60,000 - 90,000 miles), many owners carefully research different VW timing belt kits and the individual components. If you've researched VW water pumps at all, you may have noticed a controversy regarding metal impellers and plastic impellers? We discuss symptoms of a worn or bad VW water pump. 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? Do you want your VW water pump to last 60,000 to 90,000? Common statements and questions regarding VW water pumps are addressed and explained.
Post Contents [hide]
- Symptoms Of A Worn or Bad VW Water Pump
- Crucial VW Coolant Flush and Fill Information
- VW Water Pump Leak
- VW Water Pump Noise
- VW Engine Overheating
- VW Water Pump Diagram and Functions
- VW Water Pump Replacement Intervals
- Basic Overview of How to Change or Replace a VW Water Pump
Symptoms Of A Worn or Bad VW Water Pump
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 have 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) 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. 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 2.8L V6 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.
Image 2) Water pump removed from a VW 2.8L 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.
Crucial VW Coolant Flush and Fill Information
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 cannot 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 its related components. Often when problems arise, such as a coolant leak, the new VW water pump is blamed as the cause when in 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 present) 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 affect 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 OEM 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 OEM 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.
VW Water Pump Leak
"I have a coolant leak. How do I know if it's my VW water pump?"
"I see coolant on the ground after the car has been running and is then parked. Could the water pump be leaking?"
"My VW water pump appears to be leaking. What should I do?"
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 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 driver’s side? Common coolant leaks originate from coolant hoses and the expansion tank. The expansion tank often becomes brittle and leaks below its location (in front of the driver’s 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.
VW water pump usually leaks from the following areas:
- VW Water Pump Shaft Bearing or Seals
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 OEM approved coolant.
See Crucial VW Coolant Flush and Fill Information and Blauparts VW Water Pump Replacement 'Service Bulletin' pdf.
- 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 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
Incorrect Use of Water Pump Sealing Agent
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 using 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.
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 (very simular to a VW V6 2.9L) 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.
- 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.
VW Water Pump Noise
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 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.
-"There is a noise coming from the front of my engine. Is it my water pump?"
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 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.
VW Engine Overheating
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.
VW Water Pump Diagram and Functions
Circulating the coolant through the cooling system is the main function of a VW water pump. The water pump driven by the timing belt, circulates the coolant throughout the engine by centrifugal action of a finned impeller on the VW water pump shaft. As the engine runs, the timing belt revolves around the VW water pump pulley, rotating the water pump impeller, which is within the cooling system, causing the coolant to circulate.
Where the VW water pump was once a commodity product, it is now considered to be a crucial technical component of coolant and engine systems. In the course of engine development, the engineer's primary target is to achieve the BEST engine performance and efficiency. In order to accomplish this, the water pump needs to produce and maintain precise coolant circulation rates. These rates sustain optimal engine temperature, fuel economy, and emissions.
Although there has been major focus put on the water pump impeller, it is the internal bearings and seals that contribute to a VW water pumps life span. Some aftermarket manufacturers don't use the OEM designed water pump bearings and seals. If your VW model is designed to use specific water pump components, replacing them with ones of differing geometries, material, weight, shape, or profile will negatively affect the intended performance and reliability of your car. Blauparts only supplies the highest quality VW water pumps that are manufactured using the OEM design and components (i.e. internal bearings, seals, impeller).
Blauparts supplies water pumps that use the OEM design. Including genuine OEM heavy duty bearings and seals (see VW water pump diagrams). These pumps are individually tested using specific sealing porosity tests, involving resistance of the flange/pulley and impeller to axial movement. What does all this mean? Significantly greater reliability over other aftermarket pumps! This trusted company is the OEM (original equipment manufacturer) for BMW, Ferrari, Maserati, Alfa Romeo, Lancia, Fiat, and Ford (Europe). One more reason to look to Blauparts for all your VW timing belt maintenance needs!
Correct installation is the biggest contributing factor in a VW water pump's life span. Do you expect your water pump to last 60,000 to 90,000? When performing this crucial engine maintenance, it's important to take the time to re-create your engines condition as it was when it left the factory line. You cannot be lazy when it comes to timing belt and VW water pump replacement! Cutting corners now adds time, labor, and money later. See our Blauparts VW water pump replacement 'Service Bulletin'.
VW Water Pump Replacement Intervals
Wondering if it's time to change your VW water pump? It is important to follow the vehicle manufacturer's water pump replacement schedule. As a rule, timing belt and VW water pump replacement should be done every 60,000 to 90,000 miles. A VW water pump provides reliable service and is typically a maintenance free part within its suggested life span. Since the water pump is a key component of the cooling system, changing it at the specified service interval is very important. Replacing the VW water pump during a timing belt change is recommended. Remember that the timing belt and water pump work closely together (timing belt runs the water pump) and have a similar life cycle. VW water pump failure symptoms are often seen around timing belt replacement intervals. Therefore, Blauparts only sells the water pump in a complete VW timing belt kit.
The older a vehicle gets (i.e. over 100,000 miles), regular inspection of the VW cooling system becomes a more essential part of preventative maintenance. Checking the radiator, expansion tank, hoses and connections is often associated with high mileage engines.
Basic Overview of How to Change or Replace a VW Water Pump
This is a basic overview of how to replace a VW water pump and timing belt. The location of the water pump on most engines is directly behind the timing belt on the front side of the engine. VW inline mounted engines must be put into the service position first. When the front bumper is removed, special tools are used to support the radiator valance, enabling the valance to slide out about 6-8 inches. The whole front of the engine is then accessible for repair. For transverse mounted VW engines, the front of the engine is accessed through the passenger side wheel well and over the fender.
Remove all serpentine belt(s) and accessory belt components. Remove all timing belt covers. Set engine timing. Utilizing special factory tools that lock the crankshaft and camshaft in place is a crucial part of the replacement process. When this is complete, all the timing belt components, water pump, and thermostat can be replaced. Replace the timing belt, tensioners, idlers, tensioner damper, as well as any seals showing signs of leakage. All the timing belt components including the water pump have a similar service life of 60-90k and should be replaced at the same time.
The typical VW timing belt replacement service takes between 6-10 hours of labor, dependent on vehicle engine and condition. The VW water pump replacement cost will depend on each repair shop's hourly labor rate. When replacing a VW water pump or timing belt, always refer to and follow the factory manual. Blauparts recommends having an 'Audi VW Factory Trained ASE Certified Technician' install your parts.
Installation Note: During VW water pump and thermostat replacement, the coolant system needs to be thoroughly flushed (no short cuts). Thoroughly flushing the coolant involves flushing the engine block, radiator, and heater core. See the 'How to prevent your water pump from premature failure and leaking' page and Blauparts VW water pump replacement 'Service Bulletin' for details.
Please see the 'How to prevent your water pump from premature failure and leaking' page for some important DOs and DONTs of VW water pump replacement.
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