DIY: How To Replace the Water Pump on the IS250 - Club Lexus Forums

DIY: How To Replace the Water Pump on the IS250

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Old 01-15-14, 01:21 PM   #1
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Default DIY: How To Replace the Water Pump on the IS250

This is the first big repair I ever done on a car and my first write-up. Feel free to make any corrections or suggestions as I am not a mechanic. Just a dude with some tools to fix minor problems lol. The job took me about 3 hours.



Leaking water pump

What You Would Need:
10mm, 12mm, and 14mm socket wrenches
Torque Wrench
Breaker Bar
Large pliers to remove hose clamps
Loctite Blue 242 Thread Locker
3/8” inside diameter vinyl tubing
Toyota Super Life Long Coolant (2 Gallons)

Aisin WPT-137 water pump. Aisin is the OEM provider for the water pump. You can find it on Amazon for $84.
Aisin WPT-137 Engine Water Pump : : Automotive Aisin WPT-137 Engine Water Pump : : Automotive

As you can see, Toyota is etched off. It should come with a gasket and 2 O-rings.

Remove engine covers and cool air duct that attaches to the air box. Remove the 10mm bolt and slide it to the right to remove.

Now you need to drain the coolant. Attach the 3/8” vinyl tubing to the drain plug at the bottom of the radiator. Remove the radiator cap, and then turn the drain plug slowly until you see coolant draining out. Do not fully remove the drain plug.

Remove Plastic covers. One is covering the water inlet and the other one covers the top portion of the Injector Driver.

Remove water reservoir by removing the 2 10mm bolts.

Slightly loosen the 4 bolts on the water pump pulley before removal of the serpentine belt. The belt helps hold the pulley in place.

Using a breaking bar of your choice, release the tension of the tensioner pulley by turning to the left. I bought a cheap 24” breaker bar at Harbor Freight for $9. Attach it to a 14mm socket.

After removal of the belt, you can now take off the water pump pulley.

Disconnect the 6 hoses with pliers.

Remove the 4 bolts and nut holding the water inlet in place. I forgot to take a picture of the bolt locations, but here is a diagram.

Once the hoses and all bolts are removed, carefully pull out the water inlet towards you. It was a little tough at first, but just keep tugging.

Remove these O-Rings. You will be replacing them with the new ones supplied with your water pump. You can replace the smaller O-Ring now, but you cant replace the bigger one yet until you put in your new water pump.

Remove the 3 10mm bolts holding the Injector Driver and move the driver to the side. I did not have to unplug any of the plugs to the driver.

Remove the 2 pulleys. The tensioner pulley (Green) is left hand threaded, so turn right to loosen. Pulley #2 (Red) is normal thread, so turn left to loosen.

Remove the 16 bolts (12mm) on the water pump. There would be 3 different size bolts. Large (Bolts A), medium (Bolts B), short (Bolts C). Be prepared for a waterfall of coolant to flush out after removing the water pump. Get a bunch of rags ready, cover the floors, cover the pulleys, etc.

Here is the old water pump

Now its time to put on that shiny new water pump and the gasket. Don’t forget to add a drop or 2 of the Loctite Blue thread locker to the bolts.

For the large bolts (Bolts A) Torque to 21 Nm (214 kgf-cm, 15 ft. lbs.)
For medium and short bolts (Bolts B and C) Torque to 9.1 Nm (93 kgf-cm, 6.5 ft. lbs.)

That’s it! The hard part is done. Now its time to put everything back.

Reinstall the 2 pulleys. Torque to 43 Nm (438 kgf-cm, 32 ft. lbs.)

Reinstall the water inlet. Torque the 4 bolts and nut to 10 Nm (102 kgf-cm, 7 ft. lbs.) Make sure you replaced the O-Rings!

Reinstall the water pump pulley. Torque to 21 Nm (214 kgf-cm, 15 ft. lbs.) It would be tough to tighten as the pulley spins. So wait till you put the serpentine belt back on to torque it to specs.

Good time to replace your serpentine belt if you want. Reinsert all hoses, plastic covers, and water reservoir.

Add Toyota Super Life Long coolant. Don’t forget to bleed out the air. Check for leaks.

You are now done and saved yourself $600+ if you are out of warranty like I was.

Last edited by Serifiyah; 06-21-15 at 03:01 AM.
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Old 01-15-14, 01:45 PM   #2
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GJ, nice pics and good write up. I'm probably going to have to do this sometime down the road, thanks.
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Old 01-15-14, 01:45 PM   #3
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Bravo! I spent $600 at a mechanic about three years back. You just saved a few people some money.
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Old 01-15-14, 01:50 PM   #4
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thank you for sharing....
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Old 01-15-14, 01:57 PM   #5
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I'm so glad mine failed before the powertrain warranty expired....
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Old 01-15-14, 02:07 PM   #6
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This is a great write up and will benefit many on the forum. Thank you!
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Old 01-15-14, 02:16 PM   #7
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You got to it before I did. I was gonna do a write up of my water pump change but its too cold for me to do a water pump change now. It seems pretty straight forward compared to other cars that Ive driven.
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Old 01-15-14, 02:21 PM   #8
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no way will i be attempting this, but awesome write up! great work!
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Old 01-15-14, 02:31 PM   #9
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heck yeahhh! i been needing to change my soon!
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Old 01-15-14, 02:35 PM   #10
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Wow this a very well presented DIY. Definitely bookmarking this for when the time comes. Thank you OP!
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Old 01-15-14, 11:14 PM   #11
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Thanks guys. Hopefully you won't need it, but if you do, its here. Lol

Last edited by Serifiyah; 01-26-14 at 04:44 PM.
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Old 01-15-14, 11:20 PM   #12
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great write up, will def keep this booked if and when that time comes,
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Old 01-16-14, 02:53 AM   #13
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Thanks for DIY. How do you bleed air from the system?
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Old 01-16-14, 07:20 AM   #14
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nice write up! i've been waiting for someone to make a diy for when the time comes i need to replace my water pump. i feel much more confidant doing it myself now. this should be added to the diy sticky.
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Old 01-16-14, 09:16 AM   #15
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Nice write up,
Suggestion: This is the best time to change the belt while you're at it.
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