Hi Blackrock,
Welcome to the forum.
We list the real OEM (original equipment manufacturer, or simply the people who supply Porsche) Waterpumps on our online shop at http://www.jmgshop.com/water-pump---944-2730-all-models-inc-lux-s2-and-968-149-p.asp
If you are a TIPEC member, you get 10% off of that price.
The only real difference between an OEM waterpump and a Genuine Porsche one is the box it comes in, sometimes with OEM parts the part number embossed in the item has been sanded off, this is normal and due to the manufacturer only being allowed to sell to other distributors other than Porsche as long as they do not carry the Genuine Porsche triangular stamp and the Porsche part number, which are both legally owned by Porsche.
There is a chance that your old waterpump was what some online suppliers call and OEM waterpump, which should really be referred to as an "Aftermarket" part, which in some cases can be really inferior and may explain why your one did not last.
There is even one national supplier of Porsche parts which was selling brake disks a couple of years ago they called OEM, unfortunately they sent me some of these OEM parts.. They were not "Original Equipment Manufacturer" parts, but instead seemed to be made by a company called "O.E.M" and were really nasty quality.. The other suspect thing about them was they had "Made In Germany" as a sticker on the box... When I pressed the manufacturer they admitted the "Box" was made in Germany, the disks inside were made in India... I
ing play on words and skirting around the law, but stuff like this goes on all the time... Then of course you get the counterfeit parts, such as Bosch MAF sensors for Boxsters, identical to a real Bosch one, but actually fake from eastern Europe, I have had these bought to me by customers wishing to supply their own parts in the past, and one of the reasons I am not keen on fitting customer supplied parts... They are not just poor quality, but when spotted can make a mockery of my busy schedule where all of a sudden we can't repair the car or do other work while we wait for a customer to call us back.I typically recommend the belts are changed every 4 years, even if the car has not turned a wheel, the rubber in the belt breaks down with age and becomes exponentially weaker with every month after 4 years. As far as wear is concerned, 40,000 miles is the point where the belt begins to wear to a point where it is weaker. So you really need it changing every 4 years or 40,000 miles, whichever comes first.
The waterpump, tensioners, rollers and front engine oil seals are usually recommended to be changed on your car every 8 years, or 80,000 miles. The seals in the tensioner and roller bearings, the waterpump and the engine oil seals, tend to last 8 years before they also begin to degrade, which is why a little after this time all these components become noisy or fail, is because without the seals the items are no longer able to perform correctly.
There is always a chance that your old waterpump was a genuine one or an OEM one, but if it has been in stock somewhere for 4 years before you got it, there is always a chance it was age expired before you even had it installed. It is another reason why we buy direct from the manufacturer..
If you buy from a main dealer or even Porsche GB, they do not rotate their stock like a greengrocer would perishable items, in other words, the first pump they bought would be the first onto the shelf, possibly years ago.. then whenever they get down to a certain number remaining, they will order more... But if you buy at a time when their stock is low, you are more likely to get an older and older pump that has been in stock for donkeys years.
A good example of this was a couple of years ago where Porsche were selling 964 Turbo brake calipers VERY cheap, the reason was that they discovered that they had a stock where the Porsche warehouse in Germany had lots of sets, that had become dusty at the back of the shelf, where the front of the racking had been sold and replenished many times over, the result was that although these calipers were in perfect condition, they knew they were anything up to 15 years old and the seals were rated with a lifespan of 8 years... they were probably ok, but Porsche did not want the risk of selling them as new items.
So there are several reasons why your waterpump may have failed already, but I think it is possibly for a very good reason.
Your belt being loose could be because it is weakening with age, which will make it slack.. the other thing, did you have it retensioned after 1500 miles? Sometimes a new belt, in particular some manufacturers (Porsche themselves use 3 or 4 belt manufacturers) can de-tension between 400 and 1200 miles after installation, this is down the the specification of the materials and the amount of "flashing" left from the belt molding process.