Originally Posted by jimbunyard
The alignment procedure outlined above is to align the seawater pump adaptor (drive) plate, which bolts onto the drive gear
with three bolts and holds the drive key that actually drives the pump. See picture below.
It is clearly stated in the manual that that procedure should only be used if the adaptor plate has been loosened or removed and the alignment tool is unavailable, and is considered an interim method until the proper tool can be obtained. See page M4 in the manual linked to below.
Non-Perkins alignment tool.
Is should also be noted that the 4108 uses Sherwood, Johnson and Jabsco
pumps and the drives on all three are about 7/8" in diameter, the same as the key that drives them.
The shaft that Monty shows in his original post, is clearly missing the 'coupling' (which looks to be hardened steel
in the picture) that increases the size of the shaft to match the larger dimension of the drive key. This is likely the cause of the wear observed in the picture, but if someone has loosened the drive plate and not realigned it properly, that could be the end cause of the observed wear, and indeed, could have caused the 'coupling' to break, (in which case the two halves are lying in the oil
pan or bottom of the gear
housing), but the root cause is the reduced drive area caused by the loss of the coupling...
Coupling is #2 below (12442, not available separately).
And finally, again, sealant
required on gasketed joints, unless the surfaces are badly corroded, pitted or scarred. Granted, there are, in rare cases, 'problem' joints that have to be 'sealed', but by far the cause of gasket leaks
is improper or inadequate cleaning
(a side effect of gluing gaskets on if not specifically specified) and distortion induced in flanges caused by overzealous tightening, oftentimes enough so that the mating flanges have to be dressed down with a flat file to re-obtain proper sealing surfaces.
There are two different adapter plates. There's the 3-bolt thing shown in Jim's rusty picture, and then there's the 4-bolt thing shown in Lepke's early post, and more clearly in squarepeg's post, with an alignment tool inserted.
The 3-bolt thing (part 12632 or Part 20004 on a Westerbeke
, using the old part numbering system because it's what I've got, and shown as part 30 on the diagram) is listed as "hub" and guided by a bearing that aligns it with the drive on the injector pump
. There's really not a lot of "alignment" possible. Part 32 on the parts
diagram is labelled "shaft", and is the thing with the tab sticking out that drives the water pump.
The water-pump's shaft needs to align with this "tab shaft". Perkins made an adapter plate (the 4-bolt thing) onto which the water pump attaches. If this isn't well-centered on the tab-shaft, problems ensue, so the alignment tool shown so nicely in squarepeg's picture has to be used to get it aligned.
took a rather different approach: they made a metal ring with four studs; the ring sits inside the timing-cover, and the four studs protrude outward through oversize holes. Once you put a few "fiber gaskets" (to get the tab-shaft-to-pump-shaft distance right) between the timing cover and the water pump, you can screw on the pump and snug up the four screws...lightly. Then you turn the engine
through a few revolutions and try to nudge the pump into a position in which it doesn't move around while the tab-shaft is turning. This is surprisingly easy, and can even be done with the engine
running; the sweet spot is pretty clear, and when you find it, you snug down the four nuts and call it a day.
If you tried to use an alignment tool in this situation, you'd have the problem that removing the tool (which might fit over the tab-shaft and the tip of the pump-shaft, aligning them) would require removing the pump...which would let that ring-with-studs float around so that you'd lose all alignment.
Short summary: with the Perkins "make everything rigid" approach, you need an alignment tool, although not for the "hub". For the Westerbeke, "let it float a bit and figure it out as you install" approach, an alignment tool is really of no use.