How To Install a Lexus GS300 Water Pump

If your Lexus GS300 is overheating and it doesn’t appear to be an issue with your cooling fans or thermostat the next logical part to check is the water pump. When your Lexus GS300 water pump starts to give out, the coolant in your 3.0 liter inline six engine won’t circulate properly. When this happens there’s a good chance that your engine could overheat or blow a head gasket.

Today I’ll be showing you how to install a GS300 water pump in a 2000 Lexus with the 3.0 liter engine in it. Before you begin it’s a good idea to start when the car is cold, and have the proper jackstands and automotive jack if you don’t have access to a lift.

Raise the front of your Lexus and secure it safely. You’ll need to drain your radiator and disconnect the radiator hoses. It’s best to remove your radiator assembly completely before you begin, as you’ll have to undo the pulleys and drive belts.

Now undo the tensioner to loosen the accessory belt, and remove the belt completely. It’s best to do this from your power steering pump side. Because you will be removing the front engine cover, it’s a good idea to have your intake removed. It’s not required but it’s a good idea to have your intake box and engine cover taken off ahead of time.

To do this you’ll need to disconnect the mass air flow meter, and remove the 10mm bolts holding the top of your engine cover in place. Again this isn’t a necessary step but it’s recommended.

The next part is to remove your engine cover, or at least gain access to the timing belt assembly. To do this you’ll need a T30 safety socket or a 5mm metric hex. Remove the hex bolts that run through the front of the engine and into your valve cover.

Once you’ve got these bolts removed from either side of the top timing belt cover, you can turn your attention to the rear bolts on the front of your engine cover.

Now that you’ve got those free you can slowly wiggle off the front engine cover. This should give you access to the timing belt assembly, as you’ll need to remove the 3.0 liter Lexus tensioner to take off the GS300 water pump.

The top of your 3.0 liter inline six engine should now be off. You must now remove the mid cover on your 2JZGE engine to gain access to the tensioner bolts. Remove the bolts that run through the middle of the engine, holding your mid cover in place.

Now you’ve got to remove the crank bolt that holds your crankshaft pulley in place. This bolt can become stuck over time and even freeze, so if you have a problem with your 2JZ crank bolt, check our guide here.

Once you have your crank bolt taken off, use a gear puller to remove the crank shaft pulley. Now remove the bolts that hold together the lower timing cover. Once these are removed, the harmonic dampener is what’s holding the bottom engine cover in place.

Slide off the crankshaft pulley to your 3.0 liter Lexus engine, and you should now be able to remove the lower engine cover. Now remove the 10mm bolts and nuts from your water pump and slide off the water pump pulley.

With the Lexus GS300 water pump pulley removed you should now be able to access all of the bolts that are holding the lower timing cover in place.

Remove the last bolts holding the lower engine cover in place, and you can now slide off the bottom timing belt shield. Now you can remove the 14mm bolts that hold on the tensioner and remove it.

Once this tensioner arm is taken off, you will need to remove your 2JZ timing belt tensioner. If you are planning a timing belt change, now is a great time to do so. If you are intent on keeping your timing belt and tensioner, push a cotter pin through the hole in the GS300 timing belt tensioner rod.

Now that your 3.0 liter Lexus timing belt is loose, slide it off the camshaft gears and your crankshaft.

Now you can remove the two 14mm bolts that run through the tensioner. Remove this tensioner and now undo the hex bolt that holds the tensioner arm in place. Take off the 2JZ timing belt tensioner arm, and now you can access all of your water pump bolts.

Remove all the 14mm bolts that hold your GS300 Water Pump to the front of the engine. Take off the bolts that connect the upper water pipe to your cylinder head, and you are now ready to remove the entire water pump.

Make sure to take care when removing from the main water pipe that runs along the back of your engine. You may need a replacement o-ring at that rear water pipe in case there’s damage or a tear in the o-ring.

If your replacement water pump is the entire assembly, great! you can simply install your new one now. However most aftermarket GS300 water pump units are sold as the front half only. This means you will have to remove the old front of the water pump and install your new one.

Once you have your new water pump front installed, you can go ahead and reinstall the entire assembly. Make sure to apply high temp RTV and replace the gaskets and o-rings where needed.

When you have your replacement GS300 Water Pump installed, you can go ahead and install your new timing belt and reassemble the front of your engine. Fill with coolant and make sure to check for any leaks before starting.

Have any questions about this GS300 Water Pump DIY Guide? Leave us a comment below and let us know!