20vt water pumps

Dave Eaton Dave.Eaton at clear.net.nz
Sun Jul 15 19:43:40 EDT 2001

as some will know, the rs2 has a unique water pump (034 121 004b), while all
the other 20vt's have the same pump ('a' suffix).

for those interested in retro-fitting the rs2 pump, the following
differences need to be born in mind:

1) measurements:
front ribbed pulley:
rr/aan/aby: width 72.0mm, depth 24.7mm
rs2: width: 64.9, depth:21.0

rr/aan/aby: w: 73.0mm, d: 18.0
rs2: ditto

front of pulley ribbing to rear of impeller: both pumps 89.3mm

front of pulley to rear of impeller:
rr/aan/aby: w: 103.8mm
rs2: 89.3mm (i.e. the rs2 front pulley has the same depth of ribbing, but no
"dish", while the other pump has 13.5mm of "dish".

2) fitting:
the earlier 20v pump has a method of adjustment (tensioning) using 2 of the
mounting bolt holes.  the rs2 doesn't, as it uses a separate adjustment
mechanism on the damper (054 109 479a)  this tensioner is shared with the
later 20vts, the rr/3b doesn't have it.  remember that the earlier motors
also used the 147 tooth belt (054 109 119a), while the later ones had the
151 tooth one (054 109 119h).  the adu has another cambelt (034 109 119c)

impeller design:
very much the same, except that the rs2 impeller is steel, while the earlier
one is plastic.

so, in summary, the rs2 pump won't work with the 3b/rr without the use of
the separate damper, belt, and camshaft sprocket.  it is unlikely to work
with the aan/aby motors due to the different depth of the pump pulley, and
the requirement for a different belt/sprocket.

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