I used to always use GMB Japan water pumps on any engine and got 7-10 years no worries and plenty of km's, Last time i replaced the waterpump on the VS i couldn't find another GMB Japan pump so i use a normal GMB Pump which didn't have Japan on it like my last one, well it only lasted 2yrs and nearly 40,000km, When i bought the VX i didn't want another GMB Pump and still couldn't find a GMB Japan pump so i bought a genuine Holden pump and guess what it only lasted 2yrs and 30,000km, both pumps had water coming out the bottom bearing breather hole, all pulleys straight and aligned well, no vibrations and well no pump problems like this before.
So I found a GMB Japan pump this time so ive taken a heap of photos to compair them all, the only difference i can see is that GMB Japan has the Japan marking on the front, markings on the inside and bigger bump in the middle of the pulley, so it requires the older ecotec pulley hub with the open centre. Time will tell if the GMB Japan pump will last the normal 7-10yrs or not.
I busted the old Holden pump open to see what bearing it uses and what the seal was like, doesn't look bad, it should be sealing, bearing is a TZP brand, So my thoughts are Holden isn't making pumps for these anymore so they use cheap stuff same with GMB they have a low end pump and then there Japan made models. Ive also taken photos of the box's to compair, by the looks of the box id say GMB has someone else make there cheap pumps.
Part Numbers GMB Japan 1039 Cheap GMB WP1039MGMB