This being the second of no doubt numerous questions re the 1989 Dodge B250 camper I just bought for a summer roadtrip. Engine is the 318 V8 with 120k miles. Tranny was rebuilt in '99 at about 60k.
Problem: beginning about 40 mph, and growing increasingly severe with speed, is a low-frequency rumble/vibration, probably in the 20 Hertz range. Significant enough that I didn’t want to drive home faster than 50-55 mph. Could feel the whole vehicle vibrating, through the drivers seat, NOT through the steering wheel or pedals. Definitely not the engine, because as soon as I let off on the gas, the rumble/ vibe disappears. Get back on the gas and it returns full force. Definitely a drivetrain problem, only under load, that disappears when load it removed. My best guess is it felt something like I’ve heard described as a bad U-joint, something I’ve never experienced in person. The tranny shifts fine and doesn’t feel like it’s the problem, unless maybe it’s something to do with the torque converter at highway speeds?
I’m taking it into the shop next week for diagnosis and repair, but I’d be interested to know in advance what the range of possible causes might be. Will report back after diagnosis with bonus points for correct guesses!
PS, correct me if I’m wrong, but when I pulledoff the highway to check underneath, it looked like this van has 2 U-joints. Is that correct? The van has a rear body addition for the camper bathroom.
Also, the van has been sitting almost unused for almost 2 years, except for an occasional run around the block to keep thr blood flowing. Would that lack of use perhaps. contribute to a U-joint seizing up?