I happen to be in the market for something along the line of an '04-'06 LS and am of the belief these are among the best made cars one can find. So far I seen several posts and YouTube entries often mentioning water pumps, A member here has a one owner Gen3 very well maintained and low 67k miles. Already the water pump has been replaced. Not to mention timing belt and the exhaust, which really baffles me. I will paste his words below:

" Maintenance at every 5k miles performed. Timing Belt, water pump and exhaust all replaced"

So, I invite advice from those much more experienced on the Gen3 LS than am I to help explain these things. Thanks in advance.
BTW, I'm very new here, but I'm not trying to build a comment score in order to sell something in the Market.

 

Pumps are consumables that can age out, a 20 year old seal might have issues holding if the car hasn't been used much. Generally speaking when cars are about this age it's wise/necessary to reseal everything. I did so when I picked my 430 and it's like a new car now in the sense that all consumables (fluids/filters, all suspension, all belts, all flexible parts, rad, bulbs, cam/crank seals) are replaced.

There is also the simply fact that if you are going to bother to do a belt you should always do the pump, tensioner, and idler as well. No sense going that far in and not replacing at least the pump, the other items are so high quality that OE units can sometimes last 200k plus.

Older cars, even really well designed ones like the LS require stuff like this. The only exception would be garage kept ones that don't see rain and are driven weekly.

 

That makes sense. I didn't know the water pump was right there kind of looking at you when changing the timing belt. I mean on the face of it, 67k miles seems early for a timing belt, but years of age has something to do with it too, and I am getting the distinct impression Lexus owners, at least around here, can be rather meticulous when it comes to maintenance. Which is, of course, one heckuva good thing. Thanks much, Stryker223

Now, on to my search. I need to mention I found a beauty of a one owner '04 Base, 131k, black/black, at a local Lexus dealer. And by that I mean I found their ad for it. Went the next day and it was long gone. They wanted $11,009 for it. I have had a bad case of "the one that got away" ever since.

 

I'm at 157,000 miles with the original water pump.

 

2005 ls430. I supposedly did my timing belt at 90k In 2014, with the pump. At around 135k, 4 years later, my car started to get warm, heard fans kicking in. Drove it short distance (after it cooled down, I caught it early) to a place where they said pump was leaking. I had learned not to trust the place the did the original timing belt, and not sure they really did it or the belt. Scammers. So maybe the water pump was never really replaced at 90k. But since it was open anyway, did the timing belt again. So I won't have to touch it again I hope until 2027. Still felt like a waste of money. I usually go to dealer for service but for first timing belt I went locally. In any case, at 145k my car needed the pump -- leaking coolant. Do it when you do your timing belt.

 

When you see statements like this it's basically a selling point to hopefully give any prospective buyer some assurance the car doesn't need this expensive job right away.
It's prob safe to say 99.9% of LS water pump replacement is simply preventative maintenance as part of a TB service not because of an issue or failure. Same with the TB these parts will last a long time but you HAVE to be conscious of the time frame and mileage