Water pump OEM Toyota or GRAF

I've run the plastic pump on 2 different cars for over 100k no issue, in fact I only changed one because the thermostat went bad and the water pump's reputation. I do have the metal Graf pump now, I like it so far.

I got the graf as well, def better than what the previous owner used

Graf is fine, I've put a bunch of them in 240s over the years, none have failed yet.

Graf is good.

I ended up going with the water pump here: Graf Water Pump . There is no difference in engine performance or fuel economy with the new pump. But it will take longer to warm up, especially in colder weather.

I personally replaced the water pump on my Tiguan with a Graf aluminum pump. The only issue I've had was the rubber o-ring on the temp sensor leaking. I replaced all the rubber seals with Rein branded ones and no more leaks.

As for the aluminum one made by/marketed as Graf, there are a few issues in my experience. First, the rubber gasket from the housing to the block is known to fail by tearing where the link in the gasket between the two passage connect. I think this is because the gasket does not precise fit in the channel for the seal machined into the housing. On the one that just put on an engine I just put in my '12 Tiguan, I cut that link out, effectively making two seals and relieving the tension in the seal. Next, the O ring seal supplied for the temp sensor is known to disintegrate, so I got a factory seal. Last, if your engine has a late water pump currently with the clip that holds in the temp sensor, the two mounting bolts to the block at the sensor will be too short for the aluminum pump housing, so you need to get the bolts for an early water pump. Honestly, as long as you don't have any oil leaks, the latest factory water pump is fine. I generally don't trust aftermarket water pumps, as I have had too many fail over the years (not on these engines, just in general). I used this Graf aluminum water pump as a test. The quality seems good, but time will tell.

My '89 325iX doesn't put out much heat at idle, but as soon as I rev it to 2000 rpm, the heat starts coming out of the vents. At idle it is around 65°F air and at 2000 rpm it goes up to around 95°F (it is ~35°F outside today). I noticed a whistling noise that seems to come from the water pump at idle. Once the car got to normal operating temperature, I noticed that at idle coolant stopped coming out of the bleed hole. If I revved the engine a bit, coolant would flow. I replaced the water pump (Graf) 2900 miles and 3.5 months ago. My intuition is that the water pump isn't generating sufficient pressure at idle to move the coolant through the heater core.

16,000 Miles (12 months) and now the Graf is leaking. After researching it seems a few bearing failures, a few thermostats, and some sensors out of the box are failing on these Graf pumps.

I just bought one of these Graf aluminum pumps for an engine that I am building, but before installing it I asked around with the VW tech friends I know what their impression of it is. The consensus was "not great". One shop had to warranty two of them because the seal to the block failed, tearing at a T where it connects the two passages.