Saturday, December 11, 2010

AC Pump

     When I removed the air conditioner water pump from the forward bulkhead, I noticed that the cheap plastic mounting bracket was badly deformed, and one mounting ear was broken off. The factory mounts the bracket to the forward bulkhead with small rubber grommets and screws. This method does provide a small degree of noise and vibration isolation, but not enough to suit my tastes. So, I went back to the milling machine, and designed a billet aluminum bracket to replace the plastic one. The pump itself was completely disassembled and cleaned. There was a bit of buildup on the impeller, but cleaning it off was relatively easy.
     I made the bracket out of 1/2" aluminum, and milled both sides down to about 3/16", to allow room for closed cell silicone foam to be bonded to the back side. The mounting holes are 1/2", which leaves plenty of room around the screws for rubber grommets. Finally, I made isolation washers from the same closed cell silicone, and some stainless steel flat washers. Details can be seen in the pictures.

      I ran a test after the new bracket was made and installed. The noise level of the pump has been, subjectively, reduced by about 50%. I also don't have to worry about this one deforming or breaking in rough seas. I'll try to post some new pictures from the engine room later today or tomorrow.

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