ALstew
Samba Member
Joined: November 11, 2016
Posts: 176
Location: SoCal
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 Posted: Thu Dec 28, 2017 12:35 pm Post subject: Re: WBX water pump cut open |
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Didn't take many pictures, but I got it done last night and dropped it off this morning for a full flush of the cooling system at a shop I trust.
Things went pretty smooth, and with some help of a friend that had done this before we were able to clean everything really well, use RTV, and torque everything to spec. Very satisfied. And also, the van already runs sooo much cooler than it did before.
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tencentlife
Samba Member
Joined: May 02, 2006
Posts: 10078
Location: Abiquiu, NM, USA
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| Posted: Fri Dec 29, 2017 11:45 am Post subject: Re: WBX water pump cut open |
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| me wrote: |
The impeller cavity (volute) and impeller and their fit to each other is all within the pump. The impeller presents a flat face to the engine block and no pumping occurs there. There is no impeller cavity in the block, the opening there merely routes coolant into the left cylinder box. So although the block face gets gouged by the impeller when the pump bearing fails, there's no reason to fill and repair it, it can look like the Grand Canyon but it will have no effect on pumping.
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I should explain this a bit better, since I confusingly conflated volute and impeller cavity above. In many engines, these two things are combined in the engine block, which leads to the belief that the damage a wobbly impeller causes to a wbx block will affect the efficiency of a new pump, which it doesn't.
An impeller cavity partly confines an open impeller like an automotive water pump's, such that liquid can flow in near the center and be expelled by centrifugal force from the fluid drag on the spinning impeller vanes. Look into the inlet port of a wbx pump and you can easily see this relationship.
Technically, a volute is a shaped space outside of the impeller cavity, where the liquid flows into a volume of increasing radius, which converts the low pressure and high velocity of the impelled liquid to higher pressure at a lower velocity.
The wbx pump has the impeller cavity entirely within the pump body, while the separate volute is actually split between the pump body and the crankcase. At the outer radius of either half of the volute are the exit ports, the half in the engine block ports directly into the left water jacket, the other half into the crossover pipe which routes coolant to the right water jacket.
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