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Re: UNauthorized Hyd. Pump Rebuild

Mark -

I'm one of those people who is just about to do a rebuild; thanks for
posting your experiences.

Not having taken apart my pump yet, it seems odd that both parts would
become distorted in that way, at the outsides of the mating face, since
I wouldn't expect there to be that much heat there. On an exhaust
manifold, sure, but on a hydraulic pump? Has anyone else noticed this to
be true? 

Is there any chance that the pump is actually designed to have this
curvature? Seems unlikely, I know, but if you're going to machine
slightly elliptical pistons and such, you could cast a slightly
spherical face on a pump.

- Wallace
  '87 5kcstq 150k

Mark E. Woodland wrote:
* * * *
> first (semi) warm day in January (PA,'86). On disassembly and cleaning, I
> thought it couldn't hurt to check the aluminum for distortion.  Without
> farting around with straightedge and feeler guages, I went straight for the
> "lapping plate" a sheet of 1/4" glass with a sheet of 220 grit sandpaper
> (soaked in warm water) laid flat. After a few circular passes on the face
> of the aluminum, I picked it up and took a look-Big Shock- The whole center
> of the casting was low (darker-no sanding pattern), with the edges all nice
> and bright.  It took about 10-15 min. of hand lapping to bring the whole
> surface dead flat, with an even color and pattern, plus an extra minute or
> so to tighten up on the depth of the O-ring groove.  I thought that the
> Iron side would be much more stable, but just for grins, I checked it out
> and found more or less the same situation.  (Less distortion but more time
> to remove the material..Iron is tough stuff.)  In both cases, I finished up
> with a piece of 440 grit, also wet, to go for the ultra-smooth finish.
* * * *