Retaining ac but running water pump off serpentine on 1z

[libbydiesel]

Ah, the mystery solved.  Thanks. 

[the4ork]

you could def. get the waterpump going if this was your crank pulley, which should bolt up, as its meant for a widebelt 1.8t



or a stock 1.8t



as you can see they arent that big.

both of these would under-drive the accessories, but really if your alternator is strong, and your running a larger amp unit, it shouldnt be an issue. the h20 pump doesnt need much spin on a diesel, as they are really efficient at staying cold, the only thing that MIGHT suffer a little bit is power steering and possibly the A/C, but they should run at the same rpm's at idle as the 1.8t so really were talking cruise rpm, which i dont see being an issue, a/c  might be slightly less efficient spinning at a lower rpm...

[libbydiesel]

Nope.  The belt still wouldn't touch the water pump pulley even with the small blue crank pulley.  The belt will just start to touch the water pump pulley (tangent with 0° of engagement) with a crank pulley the size of the crank timing sprocket.  That still would not give adequate engagement to make it turn and even if it did, the water pump, A/C and alt would turn at 1/2 speed.  That wouldn't be good for anything.  

As I said before, get an unobtainium CCW water pump or add a custom idler or get the Quatum pulley and v-belt.  Running the w-pump with the single v-belt is my choice as it relies on available parts and separates the water pump from the rest of the belt drive system so that any of the other unnecessary accessories can fail without affecting the critical function of the water pump.  I'd personally rather see the serp belt run everything else including the P/S pump and still keep the water pump separate.  

[bbob203]

How to run ps off serp? Would under drive mess up my tach too?

[libbydiesel]

I don't know how to run PS off the serp.  I haven't seen it done with the AAZ/1Z/AHU serp setup.  I was saying that rather than work hard to get the water pump driven by the serp belt, I would rather put that effort into separating it from the other accessories.  On the ALH they went as far as to drive the water pump with the timing belt.     

Yes, changing the ratio of either the crank pulley or alt pulley will change your alt reading. 

[the4ork]

Looks like the best option is a idler pulley

[libbydiesel]

What would make adding a custom idler and correctly sized ribbed belt easier or better than the stock bolt-on quantum water pump pulley?  The Q pulley is part number 068121029A, the shims are 068121185B (4 or 5 will suffice) and the belt is 10x650.  The pulley is still available new from VW for $60ish and the shims are less than $2 each.  

[CRSMP5]

  cause some wanna reinvent the wheel... again thanks libby.. you confirmed what i thought long time on this.. but now i need to order one as will become nla now..

[libbydiesel]

I would bet that Quality German in Montclair, CA or Brax Europarts in Montana would have them used.  I know I have a couple used sets in the parts hoard, but I also fear the day they are NLA and will hang onto them for future projects.  

[srgtlord]

Does that mean the quantum pump turns backwards?

[libbydiesel]

No.

[RabbitJockey]

the stock pump might actually work spinning backwards, it won't flow as much but i think it would work which would probably be ok in a golf/jetta scenario but not in a vanagon.  the water pumps work off a turbine and a turbine spinning backwards will still flow the same direction just as well.  you'd probably just end up with the performance of one of the ***ty "new" water pumps with the pump turbine blades that are punched out of a flat piece of metal then bent up.  but who wants to take that chance?  i know the vanagon guys already have trouble with the stamped style water pumps

[libbydiesel]

It doesn't work spinning backwards.  I've tried it.  You'll boil over on hills.

[RabbitJockey]

It doesn't work spinning backwards.  I've tried it.  You'll boil over on hills.

Thanks buzz kill

[libbydiesel]

http://www.vwdiesel.net/forum/index.php?topic=33325.0