Category Archives: Gates

WATER PUMP REPLACEMENT: THE DO’S AND DON’TS

Water Pump Replacement: The Do’s and Don’ts

Replacing a water pump requires a fair amount of technical expertise. Are you planning on installing a new water pump? These do’s and don’ts will help you avoid 9 common mistakes.

1. Don’t Worry if the New Water Pump Looks a Little Different from the Old One

It is possible that there’s a visual difference between the new water pump you’re about to install and the old pump you have just removed. Perhaps the new one has a metal paddle wheel while the old one had a plastic paddle wheel, or perhaps its shape is somewhat different. Don’t worry about these minor differences; all that matters is the position of the water pump pulley. It should be at the same height as in the old pump because – if the belt starts rubbing against the pulley – it will become frayed. To check if you’re good to go, simply put both water pumps on your workbench, face down (i.e. with the side that touches the engine), and compare the position of the pulley.

2. Do Flush the Cooling System

Not flushing the cooling system is a common mistake that could cost you dearly. After all, the old coolant is likely to be contaminated, and its impurities could settle where the dynamic seal is supposed to form. As a result, these impurities will cause scratches on the dynamic seal surface, which could, in turn, lead to premature pump failure. To remove all the debris from the cooling system, flushing is key. A hose and a standard cleansing agent might do, but using a flush tool like the Gates Power Clean Flush tool will help you to do the job properly. Tip: if you flush the cooling system with a water pump attached, use the old water pump and not the new one, to prevent impurities from contaminating the new pump.

3. Don’t Apply Sealant to an O-Ring or a Dry Seal

When changing a water pump, replace all old gaskets and seals with new ones. If your new  pump comes with a seal, make sure it’s in impeccable condition before installing it. (Some seals are so thin you could easily damage them when you rip off the packaging.) Perhaps you’re tempted to apply sealant to an O-ring or a dry seal, just to be ‘extra safe’, but these seals don’t need sealant! If your rubber ring won’t stay put, just use a drop of coolant or oil instead.

Only apply sealant if the vehicle manufacturer recommends it, and don’t use too much of it. Put a thin, even bead along the edge and wipe off the excess before mounting the water pump. If you do this after you’ve mounted the water pump, you won’t be able to see the excess sealant on the inside, where it will damage the cooling system. The sealant will clump together into chunks that contaminate the coolant and can cause leakage or do terrible damage to the thermostat.

Only apply sealant if the vehicle manufacturer recommends it, and when sealant is prescribed, be sure to use in the correct way.

4. Don’t Use Coolant That’s Old or Too Cold

Collecting the coolant from your old water pump and reusing it may seem like a sensible (and economical) thing to do, but we strongly advise against it. After all, coolant tends to deteriorate: it has an expiry date. Refill the cooling system with new coolant and make sure …

  • … to use the kind recommended by the vehicle manufacturer (don’t start mixing coolants either, because they might counteract each other).
  • … to get the proportions right. If you add too little antifreeze, your cooling system is more likely to freeze, but adding too much might also be harmful. We recommend a fifty-fifty mix of water and antifreeze (make that 65% antifreeze and 35% water for Alpine-cold or Siberian climates).
  • … to mix in warm water with your antifreeze – as odd as that may sound. Adding cold coolant to a heated engine can cause thermal shock and damage the seal, even in a new water pump.
  • … to use distilled, deionized or even bottled water, but never tap water. Regular tap water can be very hard, leaving mineral deposits inside the radiator, heater core and engine block. When these deposits break off, they can damage the water pump seal.

5. Do Rotate the Pump Manually

A lot of mechanics stick to the following procedure: replace the water pump, tighten the bolts, install the belt, tighten the tensioner, refill the cooling system … and start the engine (or just rev it up). But coolant takes a little time to get everywhere it’s supposed to be, so the water pump runs dry for a few seconds. This ruins the seal and heightens the risk of premature leaks or a noisy water pump. Instead we’d advise you to ease the car down after you’ve installed a new water pump, refill the cooling system, lift the car back up and manually rotate the pump about ten times, all the while making sure it rotates freely. Due to this rotating movement, coolant gets sucked into the mechanical seal component, effectively creating a film, which keeps coolant from spilling out.

6. Don’t Worry About Seepage from the Weep Hole

Every mechanically driven water pump has a weep hole that might leak a little in the beginning. Some seepage from the weep hole is completely normal with a new water pump: a mechanical seal has a break-in period of about ten minutes (meaning that it takes about ten minutes of operation for the seal to properly seal itself). However, if you still see seepage a few days after you’ve replaced the pump, or if you notice more pronounced seepage or even drips from the weep hole, you do have a problem: these symptoms point to a faulty installation.

7. Do Properly Vent the Cooling System

When you’re done replacing a water pump, it’s good practice to burp the cooling system to get rid of all the trapped air. Some thermostats have a small hole at 12 o’clock, and a jiggle pin which allows the air to escape (while preventing new air from getting in).

8. Do Change the Water Pump, Belt and Other Drive Components at the Same Time

It is crucial to inspect the belt drive system that is driving the water pump, while you’re at it. A bad belt and tensioner cause premature bearing and shaft failure and drastically reduce pump life. Conversely, a leaking water pump inevitably affects the belt and tensioner. That’s why we recommend changing the water pump, belt and other drive components all at the same time. Our timing belt kits and accessory belt kits include water pumps or even water pumps and thermostats.

9. Do Change the Coolant Every Five Years

Coolant contains anti-rust agents, corrosion inhibitors and lubricants for the water pump, yet these components deteriorate over time. Our rule of thumb: change the coolant every five years to preclude cavitation problems. After all, coolant tends to become more acidic over time, increasing the risk of cavitation – a bizarre phenomenon in which what seem like tiny ‘air bubbles’ pop and damage the paddle wheel and other components. (These ‘air bubbles’ actually contain super-hot vapour that can crack plastic and erode metal if it implodes). You cannot see the cavitation bubbles, but engine overheating and weep hole leaks are tell-tale signs.

TVD & Multi-Ribbed Belt Installation

Gates look at reducing the risk of premature drive system failure.


Torsional Vibration Dampers (TVDs) are crankshaft pulleys that protect components in accessory drive systems. They take out the NVH (noise vibration hardness) generated by the crankshaft. The pulleys achieve this thanks to rubber elements that connect the two main metal parts (Fig 1). The rubber is a damping agent, designed to absorb most of the vibrations. That’s why Gates encourages mechanics to install belt kits that include TVDs.

Consequential wear

Absorption of vibrations eventually causes TVD wear and sometimes misalignment. As well as providing less protection for other components, worn TVDs generate vibrations of their own. These excessive vibrations and noises are often misdiagnosed as problems caused by multi-ribbed belts.

Reasons for TVD replacement

TVDs begin to fail because:

  • Internal rubber elements degenerate through wear
  • Vibrations gradually increase
  • Worn ‘stretch’ bolts add vibrations

Top TVD tips

Drive system components that are installed together should be replaced at the same time.

  • Never replace TVDs with ordinary crankshaft pulleys
  • Cheap/fake TVDs that
    contain no damping elements could cause crankshafts to break
  • Always replace TVDs as part of belt kits

The best way to optimise performance and maximise protection for all drive system components is to install a TVD as part of a belt kit.

Replacing Thermostats Along with Water Pumps

Gates explains why it makes sense to replace thermostats along with the water pump. 


It is good garage practice to change the water pump as part of a scheduled drive system maintenance programme. This makes sense whether the water pump is driven by the timing belt or the accessory belt. In most workshops, however, thermostats are not normally replaced as part of either a scheduled timing belt maintenance programme or an accessory belt replacement.

“If the thermostat fails and the timing belt has to be removed before it is possible to gain access to it, changing the timing belt at the same time as the thermostat becomes the most appropriate solution.”

After removing a water pump, the cooling system should always be flushed to expel all potential contaminants, whether chemical or physical debris. Failure to flush the cooling system could lead to premature water pump failure. As the thermostat would prevent the whole of the system being flushed, it should be removed. It is good garage practice to fit a new thermostat and gasket after the system has been flushed, rather than risk refitting the old ones.

Common engine designs

The location of the thermostat can also be a critical issue. For example, in certain VW Group models fitted with V6 engines, the thermostat is seated directly behind the timing belt drive. Typical applications include Audi A4, A6 and A8. The Vauxhall Astra, Corsa and Meriva 1.6 petrol four cylinder engines have a similar design. In both the VW and the Vauxhall/Opel examples quoted, the timing belt must be removed before the thermostat can be replaced.

If the thermostat fails and the timing belt has to be removed before it is possible to gain access to it, changing the timing belt at the same time as the thermostat becomes the most appropriate solution. Re-installing components from the previous layout risks premature drive system failure, warns Gates.

This is because the ‘installation tension’ of the timing belt is a critical measurement that cannot be reproduced. As new belts are never reliable partners for older tensioners and idlers, new belts should always be fitted alongside new tensioners and idlers.

Timing belt kit solution

After considering the problems associated with parts identification and system compatibility, Gates devised a simple solution that benefits both installers and their local motor factor. The Gates PowerGrip Kit Plus Water Pump Plus Thermostat range means that it is possible to order all of the matching parts and to receive them in a single box, all at the same time. It should be noted that such kits for Subaru Impreza, Forester and Legacy also include a Gates spacer tool that resolves other fitting issues that had previously caused premature drive system failures on these models.

Each of these is an example of a practical and cost-effective solution for installers, with an emphasis on improving workshop efficiency and increasing installer protection. This is because there is a Gates part number for each of the vehicles mentioned so far and because all of the parts inside the box are covered by the same Gates warranty.Screen Shot 2017-07-03 at 11.04.39

Why thermostats fail

Thermostat failure is usually mileage and age- related. Most drivers only become aware of a problem when the cabin heater doesn’t work as well and, unsurprisingly, that’s during the colder winter months. A thermostat sticks shut if the wax element is damaged by

previous overheating, corrosion or age. It blocks the circulation of coolant in the engine. It’s this that causes the radiator to overheat, which could be disastrous.

‘Fail-safe’ thermostats fail in the ‘open’ position and cause the engine to overcool. This creates problems such as a slow warm-up cycle, poor heater performance in the cabin, increased engine emissions and reduced fuel economy.

The effects of an ‘open’ failure are undesirable, however they are far less catastrophic than those of a ‘closed’ failure.

Hot tips for colder engines

Gates says it makes planning for the replacement season easier by recording the fastest selling thermostats around Europe. The 2016 results are in. Check out the table below, which also includes some new-to-range items:

Screen Shot 2017-07-03 at 11.05.23

In many cases, it makes more sense to replace thermostats while the timing belt is stripped down and in these cases, the Gates PowerGrip Kit Plus Water Pump Plus Thermostat range makes things easier. All components match OE specifications, are ideal for each application and all fall under the same Gates warranty.

GATES TRAINING: Timing Belt Knowledge – Part 1

GATES TRAINING: Timing Belt Knowledge – Part 1

John demonstrates how to properly install and tension a timing belt.

GATES TRAINING: Timing Belt Knowledge – Part 2

GATES TRAINING: Timing Belt Knowledge – Part 2

John demonstrates the proper installation technique on a double overhead cam engine which includes a hyd tensioner. John finishes up with a discussion on timing belt failures.

GATES TRAINING: Accessory Belt Drive System (ABDS) – Avoid Customer Comebacks!

GATES TRAINING: Accessory Belt Drive System (ABDS) – Avoid Customer Comebacks!

Listen as John Gardner and Chase Vlieg provide solutions for solving specific problems under the hood of a Toyota along with an overview of the Accessory Belt Drive System (ABDS).

GATES TRAINING: Accessory Belt Drive System

GATES TRAINING: Accessory Belt Drive System

Check out this animated depiction of the Accessory Belt Drive System (ABDS) and its failure modes as well as the effects of these failure modes.

GATES TRAINING: Accessory Belt Drive System (ABDS) Preventative Maintenance

GATES TRAINING: Accessory Belt Drive System (ABDS) Preventative Maintenance

Have you ever heard a belt squeal? To learn why belt preventative maintenance is so important, watch this short video that will show how belt performance is critical for all the accessories in the Accessory Belt Drive System (ABDS). If the belt is not performing as intended or is slipping, everything else in the system is operating at a diminished output as well.

GATES TRAINING: Alternator Decoupler Pulley Inspection and Replacement

GATES TRAINING: Alternator Decoupler Pulley Inspection and Replacement

Did you know that some solid alternator pulleys have been replaced by a patented pulley technology that is an important part of the drive system design? These new high tech alternator decoupler pulleys (ADPs) allow the belt to power the alternator during acceleration and cruising speed, but DECOUPLE or disengage from the alternator during engine deceleration.

GATES TRAINING: Belt Wear – Neoprene vs EPDM

GATES TRAINING: Belt Wear – Neoprene vs EPDM

Learn about how a belt wears and creates slip.