How To Replace VN-onwards Commodore V6 Waterpump

Replacing the waterpump on VN Series 2 onwards Commodores is a fairly straight forward job that can be done in an hour or so and without any special tools.

One thing to keep in mind though is that being a Buick engine the bolts that secure the waterpump to the block are imperial so a 3/8 and 1/2 inch socket will be needed.

Most times a waterpump leak will be easy to spot on these engines, with the engine running coolant will be seen dripping around the area of the harmonic balancer however if you are not 100% sure the waterpump is at fault I suggest having a pressure test of the cooling system carried out first. NOTE – Do not do this job with a hot engine! Wait until it has completely cooled down.

The first step of removing the cooling fan is not absolutely necessary, however for the small amount of time it takes it does make the job soooo much easier. The cooling fan is secured to the radiator by four 10mm bolts and has one electrical connection to undo (blue arrow). The bottom bolt on the drivers side is a little tricky as it is under the charcoal cannister but is easily removed with a 10mm socket, 3 inch extension and ratchet.(Notice the crack in the radiator tank on the r/h picture – not good!)

Once you have the four bolts removed and the electrical connection undone it will take a little bit of maneuvering and the fan and shroud will be out of the way. Our next step is to loosen the four 10mm bolts that hold the waterpump pulley on. The bolts are very close to the hub of the waterpump and a thin-walled socket is best for removing these. If you have to use a open ended spanner for these be careful not to round the heads off.

Once you have these bolts loosened it is time to remove the drivebelt. An 18mm spanner is needed here, however if you only have a 19mm you can CAREFULLY use the open end to release the belt tension.

Removing the belt from the waterpump pulley first is the easiest way to remove it. If you are not confident of the layout of the belt I suggest drawing yourself a diagram before removing the belt. Next we can remove the four loosened pulley bolts and remove the pulley. Now we can see the 3/8 and 1/2 inch bolts that need to be removed. A word of caution with the smaller 3/8 bolts, the threads often have a lot of corrosion around then and can be very tight. Take your time and work the bolts backwards and forwards to avoid snapping them off.

There are two dowel pins that locate the pump and a light tap with a hammer should loosen it enough to be removed.

Now comes the fun part of removing the old gasket. Be sure to remove all of the old gasket – there is nothing worse than having to do a job twice! I find that a single-sided razor blade is best for doing this. I also suggest cleaning the bolts up with a wire wheel if you have one or a wire brush. Failing these, a piece of sandpaper can come in handy to clean the bolts.

Time to check the new waterpump with the old one just to be sure the guy down at the auto parts shop has done his job correctly. Take the gasket out and apply some ‘gasket goo’ to both sides. You can now sit the gasket in place on the two locating dowels and then with waterpump in one hand and the bolts in the other you can sit the pump in place and start winding in the bolts.

Tighten the bolts, being careful not to overtighten the smaller 3/8 bolts. All the bolts only need to be nipped up with a bit more tension on the larger 1/2 bolts.

The reassembly steps are as follows –
Fit the waterpump pulley and hand tighten the four bolts. Refit the drivebelt by fitting it to all the pulleys except the waterpump one, push the tensioner down and slide the belt on to the waterpump pulley.

DON’T FORGET to now tighten the four 10mm bolts securing the waterpump pulley.

Refit the cooling fan ensuring that the electrical connection gets plugged in. Refill the cooling system, turn the heater dial to hot and let the engine reach operating temperature, check for any leaks and ensure that the cooling fan comes on and shuts off. Allow the engine to cool and check the coolant level in the reservoir. All done!

25 thoughts on “How To Replace VN-onwards Commodore V6 Waterpump

  1. Nice write-up.

    Might be an idea to mention that the correct type of coolant should only be used when re-filling the cooling system.

    Also not a bad idea to throw in the coolant ‘tablets’ as advised by Holden. They do extend the life of the pump.

  2. Hey Craig, thanks for posting this. What should usually be an easy job is not worth buying a workshop manual for. And stuff paying my local garage $250 to replace a $80 part.

    One thing missing for me though and I’m sure it will be self-explanatory when I get started on the job, but do you mean ‘pull the tensioner up’? Is the tensioner spring-loaded is it? and automatically tensions the drive belt to the correct tension? and then, once the belt is on the water pump, let the tensioner do its job again and tighten up the 18mm bolt?


  3. Hi Greg,
    You are correct, the belt tensioner is spring loaded to maintain the correct tension on the drivebelt. Once you have the belt over the waterpump pulley you simply let go of your spanner on the 18mm bolt and the belt will be correctly tensioned.

    As you say, it will become relatively self explanatory once you get started but if you have any more questions or concerns please don’t hesitate to get in touch again.


    P.S. THANK YOU very much for your ‘buy me a beer’ donation! It will go a long way in keeping our site free for everyone to use and benefit from. Greatly appreciated!

  4. It’s also good to give the bolts a thin coating of grease after they’ve been cleaned. Helps reduce more corrosion & makes them easier to remove if the pump needs to be taken off again for any reason.

  5. I bookmarked this about 6 months ago, i KNEW it would come in handy eventually…. Today’s the day.

    Thanks for the great guide! 😀

  6. Great tutorial, However I would like to point out that on doing my VS commdore today that the power steering pulley gets in the way of removing the far left bottom bolt and you need to remove it so that this bolt can be taken out.

    Since I already had the water pump pulley off, I just put a ring spanner on the middle nut and used another ring spanner to undo the 4 small bolts on the power steer pulley, Once I removed that its easy to get that last bolt out.

    Also my tensioner nut was 15mm not 18mm.

    Hope this helps anyone else out!


  7. Hi Eric,
    Thank You for sharing that information with us. I hope one day to have tutorials covering the popular Commodores, Falcons etc., a slow process but info like what you shared with us helps towards that goal. Thanks!


  8. Hi Craig,

    No worries at all, One other thing I found that after putting all the pulleys and belt back on, Tightening of the water pump pulley nuts, was that it turned and the belt wouldn’t hold it as tight as when they were undone, Also found this on the power steering pulley as well.

    The water pump I just grabbed with my hand to re-tighten all the bolts up, and the power steer pulley just used the 2 ring spanners to do up again.


  9. Hi, just wondering, you dont mention draining the system, i would do this as a matter of course but i have read somewhere that not much coolant is lost if undrained, all the coolant in the system above the exposed holes will flow out, must be a good few litres, – or am i wrong?


  10. Thanks for the awesome tutorial, beer money will be on it’s way! My waterpump broke while I was driving and at the same time, there was a lot of power lost and the revs were very slow to drop when revving. Do you know why this is? It’s still happening after I have replaced th waterpump. Please respond! Cheers, Julian 04 990 875 52

  11. Hi,

    Looks like a great set of instructions. In your opinion could this be done by someone with limited car mechanical experience ( I normally just do the oil, plugs and oil filter change on my VS)? If so how long do you think it would take someone like me?
    many thanks

  12. G’day Mate,

    Does this also suit a VZ Commodore? The shopping trolley is overheating and I suspect the water pump is the culprit.

    The wife has asked I sort this over the weekend. Any help is appreciated!

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