I just did this and did a detailed DIY Video


See links below for the parts you need. Mostly all OEM.

Only one I recommend aftermarket is the Bando or Mitsobushi belt. These go for $13 all day but OEM is $60 for same thing.


OEM Water Pump (~$95, 2019 which is a little more than Aisin on Rock Auto or Amazon)
https://www.ebay.com/itm/FACTORY-OEM-TOYOTA-LEXUS-IS-GS-RC-NEW-ENGINE-WATER-PUMP-16100
AISIN (OEM with toyota shaved off) on Amazon for $88 Prime, https://amzn.to/2FaboV2

OEM Lower Hose (~$50, 2019)
https://www.ebay.com/itm/FACTORY-OEM-LEXUS-06-12-IS250-IS350-NEW-LOWER-RADIATOR-HOSE
(on Amazon via Bell Lexus, https://amzn.to/2FfhlQK)

OEM Upper Hose (~$30, 2019, don't make my mistake with aftermarket which requires cutting to length)
https://www.ebay.com/itm/FACTORY-OEM-LEXUS-06-12-IS250-IS350-NEW-UPPER-RADIATOR-HOSE
(on Amazon via Bell Lexus,https://amzn.to/35iATxU)

Bando Belt (~$13, definately do aftermarket if its Bando or Mitsobushi, which are OEM suppliers. OEM belt is $60))
https://www.ebay.com/itm/Serpentine-Belt-Rib-Ace-Precision-Engineered-V-Ribbed-Belt-BANDO-7PK1550
(or on Amazon for $19, https://amzn.to/2MMP0Fs)

OEM Thermostat ($55, 2019)
https://www.ebay.com/itm/FACTORY-OEM-TOYOTA-LEXUS-WATER-INLET-SUB-ASSY-WITH-THERMOSTAT-16031-31020
(AISIN version on Amazon Prime for $36, https://amzn.to/2Fdx82m)

OEM Toyota Extra Long Life Coolant (~$47 for two pack, 2019...you can get this locally at dealer, have them price match eBay, most will do it)
https://www.ebay.com/itm/NEW-2-Gallon-Toyota-Super-Long-Life-Antifreeze-Coolant

Also on Amazon for $10 more, https://amzn.to/37oCtje

 

Big tip to add to OP - drain and flush your system first.
The engine block has drains on both sides just fore and aft of the engine mounts. They look like spickets with perhaps a 12mm bolt head next to them. They drain the blocks water jacket allowing you to get all the sediment out and clean fresh fluid in.

Run the engine with them open. Just stick a hose on them like you did up front.

This way the spills of hoses and pumps being undone is not making a huge slime ridin mess.

 

Do you mean loosen the nuts and then turn on the engine? Newbie here

 

Water pump still going good...I was doing some research for a friend recently for the same replacement and notice prices went up on a few of the parts online. I updated the links and parts list above to also include parts on Amazon.

 

Tried to torque my tensioner at 43nm when installing it back. The whole assembly broke... have to buy a new one...

 

Does anyone know of a guide to change your belt tensioner assembly on a 2007 IS250?

 

I don't know of a guide, but I did it on my IS350 this spring. It isn't an easy process because the AC compressor is right in the way of all the mounting bolts. I've got three tips:
1. Remove the alternator, it will make it possible to get to the bolts on the top of the tensioner. There are plenty of how-tos on Youtube for the alternator
2. Take all of the bolts out of the AC compressor to give yourself some slack.
3. Buy yourself a cheap-ish 14mm socket and cut or grind it down to make it just deep enough to cover one the bolt heads. This will give you a hair more clearance to reach the bolts.
3a. Make sure you have a low profile ratchet, and maybe even order one of these wrenches: https://www.lowes.com/pd/Capri-Tools...nch/1002332036

 

Was it difficult to access/swap out the entire tensioner assembly? I need to swap out full assembly on my 2011 is250 awd as I suspect the tensioner spring is bad.

 

Thanks so much for posting this. It has all the important details I was looking for.
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