Have Strange Vibration/Bouncing At Highway Speeds
Hi, I am brand new to this forum, and this is my very 1st post.
I very recently bought a 2007 F-350 6.0 Powerstroke w/209K miles in the Tampa area (I live in Orlando area) that had been bought at auction in Houston, and driven to Tampa area. The interior is in super shape, as well as the exterior, except for bed and interior portion of tailgate. It had been a one owner (company) truck.
I took delivery, fueled it up in Tampa area and drove it to Orlando area with no problems. The seller mentioned a front tire had a slow leak. The next day I had tire repaired. A few days later, I went on a fairly long trip from east side of Orlando to far west side, down to Lake Placid (just north of Lake Okeechobee) to Ft. Pierce, then back home. During this trip I used less than 3/4 tank of fuel & got 18.5 MPG
As soon as we reached highway speeds (60-65 MPH), we had a weird low frequency bounce/vibration. I thought maybe they improperly balanced the tire. It kind of gets worse when going up hill like at a highway overpass, and is also worse than level ground going a bit downhill (but different than uphill).
I had also thought perhaps it is acting like a u-joint was going bad, so I checked for that when home, but everything seems quite tight.
I had tire shop rebalance tire, and they found a discrepancy, but a good balance did not help the problem at all.
Thinking maybe a motor mount problem, I rocked the truck in park, but engine seems rock solidly mounted.
Also, the engine has a bit of vibration around 1750 RPM when reving in neutral, but it is not noticed at all in the lower gears when driving.
Any ideas? Thanks!