Terrible vibration noise after installing new motor mounts on my 371

[eyyu]

The Kohler 320 runs perfectly now on my 371. I also replaced the 4 motor mounts which were badly deteriorated over the years from dripping gasoline (the last owner installed a gas tank above the engine; It has a new tank now in the OEM spot). When it’s idling, the noise level is ok. As I rev up the rpm the whole thing will start to vibrate badly especially when the throttle is 2/3 open. Most of the noise is from the metal roof. Upon close inspection, the weld on the roof metal looks as good as new. I wonder if I did not install the mounts correctly. Those are the OEM mounts I got from the Bobcat local dealer. When they first came in, they look like T-shaped rubber bushings with a metal tube in the middle. Once the bushing gets inserted into the hole of the thick metal mounting plate and torqued to spec, the leg part of the T-shaped bushing expands and flattens to form a sandwich. I’m thinking that maybe I should loosen the bolts by couple turns to allow the motor some “jumping” room beside the flexibility of the rubber parts. The noise is very annoying. Thanks for reading. Erwin

 

[OldMachinist]

How does the motor connect to the pumps? Is it a belt driven or direct coupled. I ask because if its direct coupled you may have out of alignment causing the vibration.

 

[eyyu]

How does the motor connect to the pumps? Is it a belt driven or direct coupled. I ask because if its direct coupled you may have out of alignment causing the vibration.

Thanks. It's belt driven. Erwin

 

[tsanders]

Thanks. It's belt driven. Erwin

eyyu those old kolhers run with a certain amount of vibration anyway.

 

[OldMachinist]

eyyu those old kolhers run with a certain amount of vibration anyway.

Take the belt off and run the RPMs up. That way you'll know if it's engine vibration or something down the line(Idler pulley, pump pulley or bad belt)

 

[erwin]

Take the belt off and run the RPMs up. That way you'll know if it's engine vibration or something down the line(Idler pulley, pump pulley or bad belt)

Already tried that. The vibration is the same with the engine running alone. The vibration alone does not bother me too much and I think it won't do any harm. It's the terrible noise the metal roof makes when the vibration goes bad. Erwin