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[i6941TB@gnn.com]

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To: hayasht@vrg.toronto.edu,quattro@coimbra.ans.net
Subject: Re: Water pump - O.E.M. or aftermaket?

Takayuki Hayashi asked:

>I will be getting the timing belt changed on my CQ very soon.  After
>checking the archive, it seems like a good idea to change the water pump at 
>the same time just as a precaution.  I got a quote for both O.E.M. and 
>aftermaket water pump from Clair Parts and the difference is more than 50%. 
>Can I go with aftermaket or should I stick with O.E.M.?

I always use the german aftermarket Graf (around $40). Never a problem. Don't 
confuse the reliability of the pump itself with a lousy undersized O-ring, that 
always leaks. It is just a bad design on the Audi part.

I suggest that you enlarge the groove in the water pump and use an oversized 
O-ring. A new OEM pump has the  4mm O-ring. A rebuilt one (by Audi) has a 5mm 
O-ring, yes they finally figured it out!

I always install new pumps ONLY after machining the groove with an oversized 
Viton O-ring. I had tried to locate metric O-rings in several industrial 
catalogues that I have at work. It proved to be about as successeful as my earlier
attempts to find here in the US movies and tapes with the greatest Adriano 
Celentano, i.e. exactly zero.

I found some odd size O-ring (I think it was #2-343) that was close to 5mm. The 
book usually gives you the size of the gland for a particular O-ring for the 
optimal sealing strength (mechanical engineers would probably confirm it, James 
Mariott - are you reading? ;-). I have the groove size drawing on file.

One more thing. The pump is shaped rather fancy, so in order to secure its 
eccentric cast Al body in the spindel of a lathe I had to machine a special 
mounting fixture. I also had to indicate the pump true in reference to the cutter 
after I had it installed in the lathe.

Igor Kessel
the sweetheart: 200TQ, chipped and MOMO'd through out,
in Tornado "arrest-me-officer" Red;
the ex: 5000s, the EE's nightmare
Phila PA, USA
i6941TB@gnn.com