I posted a few days ago about a vibration I was hearing at idle. It was not real loud, but persistent, and only at idle. A little throttle and it went away. Well on the tip of a member, I left her running and checked up at the fire wall for the hose connections. I found that the two heater hoses that come off of the block and attach to the firewall vibrate like crazy at idle. On top of that, the sound deadening material on the firewall, a thick, carpet pad type of material was loose and laying on top of the hoses.
I checked the underside of the cowl and firewall area, and could not locate any fastener that was supposed to hold up the insulation
. So I drilled in a small screw with a big washer, and pulled the whole piece back up to the metal.
Then I put a zip tie around the two rubber hoses, just enough to put some tension on them without strapping them together. When I got back in the cab, vibration was gone. Hopefully it will stay gone. If the zip tie fails, I may look into some braided hoses that shouldn't vibrate... .....
If your having an audible vibration in the cab at idle, give it a try... . Sarge
I checked the underside of the cowl and firewall area, and could not locate any fastener that was supposed to hold up the insulation

Then I put a zip tie around the two rubber hoses, just enough to put some tension on them without strapping them together. When I got back in the cab, vibration was gone. Hopefully it will stay gone. If the zip tie fails, I may look into some braided hoses that shouldn't vibrate... .....
If your having an audible vibration in the cab at idle, give it a try... . Sarge
