I recently disassembled my convertible top pump to inspect its condition. I think most people just replace them when they have issues. It turns out they are super simple to disassemble so I thought I'd share my pictures. Here's what I started with. It had obviously been leaking for quite some time.
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There is a large bolt that holds the reservoir onto the pump housing. With the bolt removed, the reservoir comes right off. You can see that the original fluid had turned to varnish and coated the bottom of the reservoir.
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Next, I removed the main barrel on the motor side that surrounds the armature. There are two through bolts that hold the cover and barrel onto the pump housing. The cover won't come completely off of the barrel. You can see that one of the brushes is attached to the windings on the barrel. On this motor, the brushes and points/contacts still look really good.
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Here is what the pump looks like with the reservoir and barrel removed. The armature on this piece still looks really nice without much of any corrosion. Notice there is a small check ball at the top of the armature. Mine was held in place with some old grease. Don't lose this ball. At this point, the armature can be removed from the pump housing. It will just pull right out. There is a notch in the end of the shaft similar to a distributor than engages the pump.
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Here is the other end of the pump. You can see the varnish buildup from the old fluid.
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There are 5 bolts that hold the pump cover to the pump housing. With those bolts removed, the cover will come right off. There are no springs inside so there is no pressure on the cover as the bolts are removed. You can see that there are two check balls on the inside. They kind of teeter totter on a simple valve in the pump cover.
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This is basically the entire assembly...pretty simple. There are 6 O-rings on the pump. 1 large O-ring on the reservoir, 2 on the inlet/outlet ports, 1 on the armature shaft, 1 on the reservoir attaching bolt and 1 on the reservoir fill plug.
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I bought a gasket kit on Ebay for under $20. It came with the above O-rings plus 4 mounting bushings and two large check balls for the inside of the pump. I cleaned up the pump and reservoir in my parts washer. The varnish came right off when sprayed with brake cleaner. I soaked the reservoir, attaching bolt and front mounting bracket in EvapoRust for an hour. That really cleaned up the original plating. I just sprayed them with a satin clear once they were clean. The zinc plating was worn away on one section of the barrel and didn't look good so I ended up painting it. The cover plate cleaned up nice with some 0000 steel wool, then I cleared it. Before re-assembling the motor, I cleaned the brushes and points.
Here is the finished product. It's super easy to work on. There should be no reason to just buy a new pump without at least disassembling yours to inspect it. If there is motor or pump damage, then you can look into a replacement. The only thing that gave me trouble was holding back the brushes so I could set the cover plate back on top of the armature. I ended up using an outside snap ring plyers to hold the brushes while I set the plate in place.
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