New head gasket in and engine running fine again. Could never find any reason for the failure so I'll write it off as a defective gasket.
Did a little timing work and think it's on the sweet spot .
So back to the final highway test runs. Pulls hills good, a little loss of speed on the long ones, but will run 65+ around 2500 rpms.
Now the tire vibration shows up badly. set air pressure up to 75 all around, no difference. After taking the rear duals off and running on 4 wheels, I swapped the tires around and found both fronts were the problem. Not a shimmy but a hop up and down balance problem.
Truck has 4 "Double Coin" 8.50R20 drive tires on the back and 2 "Double Star" steering tires on the front.
All were spin balanced when they were purchased. With the rears on all 4 corners, no problem at top end.
1 of the fronts has almost no weight on it (the bad one) and the other has 18 ounces (!!) on it.
Taking them back to the shop tomorrow.
Last edited by Jim Sears; 05/25/2016 2:08 AM.
