Hi
I was posting making a post on how I patched a leak in our '08 National Tropical DP. I mentioned that the water pump was terribly loud and badly installed and someone asked me to post what I would do it fix that so here it is.
These photos aren't the best. The wet bay is a rats nest of hoses and was also being dismantled for the tank repair but I think you can follow if you are taking yours apart anyway.
The first it the wet bay with the cover on. Second is the upper part of the wet bay without the cover. If you look really closely just to the right of dead center you will see a piece of a board. look closer and magnify if you can and you will see one foot of the pump.
Next it a picture of me holding the center tank support where it went as I reinstall it. The pump was screwed to a short board which was held to the top of this support above the tanks. The 2 part steel support was unpainted and would have rusted away in time so I did clean it off, prime and paint it replacing the self drilling machine that held it in place with 1/4" bolts. as you can see in the next picture. I think a lot of the noise was the that everything rattled together.
Here is the pump on the old board. Next the new oak board bolted in place on the support. Note the 4 holes drilled in the board. I got a set of these
https://smile.amazon.com/Anti-Vibrat...0750963&sr=8-4
and bolted secured them to the board with 1/4" locknuts. The locknuts were countersunk because the bolts were too short to go through the board. Then the feet of the pump went over the tops of the vibration isolaters and got nuts on them. Once the support was put back in place the tanks were now secure and the pump was mush better isolated.
I think that the noise was due to things leaning on things and things being poorly secured and shaking around when running. I suspect that the water and waste tanks were under strain also from not being secure. Simply a terrible jog of fabrication. Fastening everything down is important to prevent vibration. The board was better than metal for damping. The dampers make a difference because they allow some motion without transmission. In the end though there is still noise because the water transmits it.Removing that would need a plumbing alteration which can be done. It is much better now and good enough for me.