Engine/Transmission (1994 - 1998) Strange new vibration

[JGheen]

Well, as some of you may have seen my posts in the "non engine transmission" threads about carrier bearings and 2 piece into 1 piece rear driveline, I have narrowed the vibration down to more towards the front of the truck. Obviously, I recently put some new suspension on the truck and have developed a mild vibration, under load, that I can't figure out. At first I thought it was the rear driveline, but after doing some good research driving this weekend I could only feel the vibration from the transmission forward. So, I have been running all these possible culprits through my head and can't find anything that would cause this. I know the Cummins is a very noisy and vibrating engine when it accelerates hard but this vibration has seemed to be worse under heavy load/acceleration. I don't get any vibrations at low speeds, just at about 50mph + on the freeway when I get on it. Cruising the vibration is normal, but when I step on it to accelerate even faster on the freeway it seems to get worse.

All the engine components look fine. I inspected the entire engine/transmission and front suspension area and found nothing loose nor unusual. Sorry, if this description has not been very thorough, but that is basically the problem I am having and maybe some of you guys out there can give me another area or component to inspect for problems. I really appreciate it guys, thanks



Joe

 

[JGheen]

Over lunch time I think I may have figured it out. I pulled my front driveline off this past weekend to get a accurate measurement for a new longer one and had to put the truck into and out of 4x4 to get the shaft to spin and lock to take the bolts out fo the flange. Well, I am thinking maybe the vacuum actuated CAD had been connected for some reason , cuz just for kicks while I was at a stop light I shifted to and out of 4x4. Then suddenly as I got up to speed I noticed the vibration was pretty much gone. Maybe my CAD was connected and causing this, cuz even when I turned sharp real slow it seemed like the front axle was engaged, so I guess maybe I fixed it. Who knows.

I saw another thread on the no engine transmission posts and they mentioned looking over the axle u-joints. I have 150K+ miles on my truck and have wheeled it hard in the past and used to run 4x4 all the time when in Colorado and it was snowing, so maybe they are needing a change. Will be looking into it.