P400 water pump - this is not offical info, use at your own risk and judgement


Description
 Lamborghini
part number
 OEM manufacture
part number
 alternate
part
 alternate
part number
 approx
cost
water pump/oil pump oil seal
 GN-03760
008611704
 Gaco DPSM 17307, 17x30x7mm
 17 x 30 x 7 mm buna N seal
$10
water pump shaft seal
 GN-00632
008611703
 mechanical seal
GUARNIZ.  B-25342


water pump shaft seal  face washer
 MW-00396
1700396
 12mm x 34mm x 4mm, micro polished steel
12mm x 30mm x 4mm, micro polished steel


shaft seal backup washer
 MW-03593
 19.1mm x 34.8mm x  2mm, flat steel


impeller nut, brass, acorn
 DN-00487
 10mm x 1.5 thread x 17mm hex x 17.5 height


impeller lock washer
 RFN-00987
 tang to impeller slot, bent over lock nut, .8mm thick, 10x23


impeller key, steel
 LN-00699
 4mm width x 4mm tall x round ends


temp sender
 MB-01333
001801333
 Jaeger, France, 14, 12v, M16x1.5 , H7, 82405
Veglia  B  O  MADE IN ITALY  70-02   12-24


water "Y" O-rings - 2ea
 GN-01236
008602303
ANELLO D.24 OR 132
 24mm

water hose
 MW-03761



water pump housing gasket
 MW-00392



water pump base to oil drive gasket
 MW-03592




The Jaeger temperature senders for the panel gages are always being questioned as to their accuracy, and rightly so, they can fail or produce poor value signal. The water and oil temp senders MB-01333 are the same on a Miura.

As a quick check of a known accurate sender, the study to the right was produced in April of 2010. The sender was not heated to the end point of 130C as we only had limited shop hot water.....we achieved a steady 82C.

There was an observed reaction time of the sender to temperature increase and it was found to about 30-40 seconds for the 10 deg C increase range we tested.

Tip from Jeff north - A quick check is to attach the sensor wire to the other Jaeger sensor, which is the same unit, and read the gauge. If the gage works, replace the sensor in question.


Notes
 Graphics
Cross section view of a P400 water pump. The stack height of all the pieces in relation to the oil pump extension shaft is critical. The gasket thickness is critical. Impeller alignment on the shaft is critical. The area of the steel shaft in the water seal section, which will corrode, is not critical to the mechanical shaft seal. The area of this steel shaft in the Gaco lip seal area is critical to the sealing of oil.


additional information -
1) Oil seal installs with lip toward oil pump. This lip seal keeps oil pump oil from leaking.Generally  requires a "bullet shaft protector tool" and lubrication to install partially assembled  water pump on engine to avoid damaging this oil lip seal.

2) Water must not be allowed to leak in 3 places:
- behind the polished washer (MW-00396) as it butts up against the back of the impeller
- across the polished washer/seal face
- OD (35+mm)of the spring loaded, elastomer encased, water pump seal (GN-00632)or                   (08611703) in the water pump housing ID (35mm).

3) the seal face, micropolished washer MW-00396 was a large34mm diameter in early Lambo pumps and slightly smaller 30mm in later versions, but is not currently available in either diameter. The reduced diameter of the newer seal face washer is not a problem, but any change in thickness will create a problem. If you were to re-grind/repolish the face, you would want an appropriate shim and positive sealing for the new shim.



miuraworkshop.com