MellonC00

I know that we don't have to replace the timing belt because we have a timing chain........ I just wondered, though, whether or not 1) we have a water pump 2) when we need to change them out and 3) how extensive of a labor job it is do this.

I didn't see anything in the maintenance book.

salimshah

I did a quick search but I guess the discussion on the water pump is buried in a thread and does not have a title containing 'water pump'.

It was nicely answered by a member [sorry I dont remember the name] .. paraphrasing his words

Water pump was never an item to be replaced at any specified interval. Access to it was available at timing belt change and one could save labor cost by combining its replacement with timing belt. Now the timing belt replacement interval is gone, so wait till the water pump fails (usually leaks) and then replace it.

Salim

Droid13

I consider the water pump to be the same as any other mechanical part of the engine. Don't touch it unless it's broken, or you already had to do engine disassembly to fix something else.

MellonC00

Following up......... when water pumps go south (believe it or not this never happened to me before), how does the car behave? Is it drive-able for 10 miles or so? Or is it catastrophic?

Droid13

The standard complex answer to a simple question, it depends... You'll either have a mechanical issue, or a leakage issue, or both. The net result is going to be overheating. I would think in most cases it would be driveable for a short distance. It is unlikely any leakage will be catastrophic like a rad hose bursting and sending your entire coolant onto the roadway in a few seconds. Having the pump seize is probably the worst outcome because it will cause the belt to fail quickly too. In the RXh that's not as serious as other cars that depend on the belt for other functions like steering and electrical. But I suspect the pump would not go from normal to seize in an instance. In my case, my water pump was replaced at around 65,000 miles. The pump just got gradually louder and louder I didn't even clue in that it was going south without me, until one warm spring day I came to a stop at a red light, the engine stopped, I opened my window, and the engine started again and I thought wow, that is really loud, something isn't right. I drove for the better part of a week, before making the 45 minute highway drive to the dealer to have it replaced.

tus

For the most part, a water pump will not fail catastrophically. What usually happens is the front seal/bearing will start to go and you will start with a small leak which will gradually get worse. You will start seeing higher engine temps over time as you loose more coolant but it doesn't just spike up. The start of a leak is something you catch while doing other maintenance or while inspecting other things. The reason you see many people changing them out with a timing belt is on most vehicles the timing belt is a wear part, and by the time you get everything off for the belt you have essentially done everything needed to replace the water pump, except for actually replacing it.

The key is to keep an eye on your coolant temp and notice when it is higher than normal, and shut things down immediately if it gets into the high range.

One thing I noticed at dealerships is they bill jobs out of the flat rate book so you may not save any money by doing both at the same time. What happens is the book says 3 hours for the timing belt and 4 hours for the water pump, so they add the two and bill you for 7 hours, where in reality the mechanic will only need 4 hours to do both.

Another thing to consider, I replaced the original, not leaking, pump in my 91 Miata when I did the timing belt at 120k miles, and had the replacement fail after about a year, having to replace it again. I wonder to myself if I would have just left the old, but OEM part on, would it still be okay today.

tempestv8

Looking at the manual, the water pump appears to be fairly conventional, driven by the serpentine belt.

http://workshop-manuals.com/lexus/rx...ons/page_2027/

Therefore it doesn't spin when the engine is not running, unlike the airconditioning compressor which is driven by an electric motor.

ukrkoz

Yep, one and only belt this engine has is for WP. Go figure, and new Camry hybrids have electric WP. So no belts.
Heater core has a small pump though, to circulate coolant through when engine is not running.

tempestv8

Found another interesting quirk. The 2GR-FXE engine in the RX450h is also fitted to the Lexus GS 450h. Not surprising given the same badge numbering scheme. However, the 2GR-FXE is a little different on the luxury sedan. Unlike the RX 450h, the GS 450h employs an electric water pump, so no serpentine belt.

BenRX

Just had the water pump replaced under warranty on my '15 F-Sport at 55,000 miles. The knocking sound gradually become louder to a point that I could hear it from the driver's seat while idling at stop lights. I finally took it to the dealer, which diagnosed that the water pump bearing was failing and causing the loud noise. I did not experience higher-than-normal engine temps and dealer did not mention any leakage, so maybe I caught the problem early enough.

tus

My best guess on this would be the GS has a fore-aft mounting instead of being transverse and it's a space/packaging issue.

It is fairly common to see an electric water pump conversion when putting a V-8 into something like a Miata or old S-10 to give yourself more room and accessory mounting options on the front of the motor.