When it was in the driveway on wood blocks it ran quietly and didn't vibrate the house. Now, on the side of the house it vibrates quite a bit. It's certainly tolerable, especially if it's 30 degrees and the power goes out.
So this is my list of possibilities for the vibration, probably not any one factor but a combination of two or more:
1. The location - it's in a narrow passage with the house on one side and the rock retaining wall on the other. Other than relocate, there isn't much I can do about it.
2. The soil is sandy and soft - this might lessen once the rainy season comes.
3. The 900# generator bolted on a roughly 600# slab is now 1500# of vibrating mass - the pads helped to break the two masses apart so this seems like the easiest attack point, break them apart more with spring-mounts or more pads.
I was having the same thought. When it was bolted down right to the pad there was vibration and reverberation- when I came in the house the wife was holding her head, and she's sensitive to that stimulation overload. You could feel and hear it. the pads helped with the reverb but not as much with the vibration.
4. The exhaust expels below the level of the rock retaining was so perhaps that is adding to the reverb - getting that up higher and maybe pointed away from the house might reduce any remaining reverb. The top of the exhaust pipe is threaded, so does anyone know the size and pitch?
Your poor wife. The sound and vibration must be extra tough for her.
My baseline is that these gensets are generally pretty smooth and vibration free, so I suspect it is something about the mounting or location that is giving you issues.
I would start with getting the generator bolted to vibration isolators top and bottom as a starting point.
With that done, I suspect that for your wife's mental health, you will need to do some more.
My experience with chasing these sorts of gremlins is that there are some general rules (absorption vs dead mass), but mostly you have to iterate. I would start cheap and work up.
That rock wall is going to be a great reflector of sound. Getting some deadening on it ought to help.
I was in my local Costco recently and they were having a sale on rubber/carpet doormats 2.5'x4' for $9.99 One on top and one on each of the sides might help with the reverberation... Cheap test, and if it works, it might give you ideas on what to work on next.
A 4x6' x 3/4" stall mat from Tractor supply is $60. You could try one on the rock wall and then move it to the generator side (perhaps tied to a couple of T-posts as a test?), and then try it on top (not covering the exhaust and radiator, obviously), and see if it helps. If it doesn't it is probably returnable. If you bend them over a saw horse, you can cut them fairly easily with a sharp blade and some dish detergent/water solution.
If you do decide to reroute the exhaust, I would suggest using a couple feet of flexible pipe before switch to hard pipe. The threaded portion goes basically into the muffler with no flex. IIRC, it is NPT, 1 1/4". I can go check later.
Then there is the mass weighted vinyl ($$-$$$, thicker is better) to add to interior panels, but I would not go there without trying some of the other, cheaper things first. You probably want to couple the vinyl with 3/4" acoustic foam or rock wool or densified glass fiber. With all of the great placards inside, only the floor and ceiling are going to be much of a candidate, and I would start with the ceiling because I have seen how much mine flexes, but feel yours, perhaps yours doesn't flex much.
All the best,
2Pbfeet
