Water pump hex input shaft breaking

[samgrylls]

Hey guys,

A few months ago my water pump failed, and when I pulled it off the car, I noticed that the socket where the hex shaft inputs had broken into a bunch of pieces. I replaced it, and the new pump only made it ~200 miles before failing in the exact same way. The new pump was a Meyle aftermarket one - not sure if the old one was aftermarket or OEM. Is this a known problem with these pumps? Is it just crazy bad luck, or could there be something else going on that's causing them to fail?

One thing I was thinking is that maybe I'm missing an O ring. Is there supposed to be an O ring around the metal part where the hex shaft input is? Like around the larger diameter aluminum part, so it'd be sandwiched against the block?

Thanks,
Sam

[2004B6S4]

I haven't replaced a water pump so I can't answer many of your questions, but out of curiosity have you done any timing chain work on it? I'm wondering if you have broken guides allowing your chain to slap around at startup, and if the sudden jerking caused by the slack in the chain is what damaged the shaft? It's just a theory but I suspect that was what caused my a/c drive shaft to break even though the compressor itself was fine.

[samgrylls]

I just did the full timing service. There's still a bit of a cold start rattle, I think because of the cam adjusters (left them as-is). But the water pump is driven by the power take off chain, which doesn't have any guides that typically break - it's just one huge guide/tensioner combo. It broke after letting a guy test drive it, and he flogged the shit out of it, redlined it, etc., so I'm guessing that's what caused it. Still, you'd think these cars would be able to take a little abuse without parts breaking...