High Speed Buffeting
 

Hi folks!

I have kibitzed on this site for a few years now and have learned much. I have a situation that started about a week ago. I drive about 40 minutes to work, most of which is highway. I was passing a truck at about 75 mph and began feeling something that resembled wind buffet as I passed the truck. I finished the pass and slowed to 70 and the buffet went away. I didn't think too much of it until it happend on the way home in the clear at about the same speed (75). Best list of symptoms I have so far........
The truck needs to be up to temp and stable.
The sound has a metallic quality, like something tapping the exhaust pipe or drive shaft lightly.
It doesn't seem to happen in lower gears.
It happens whether the GearVendors is engaged or not.
Lately it has been happening at slower speeds. (65)
There is a physical "buffet" feeling when it happens.
ALL u-joints are cool to the touch.
Both diff housings are warm, but not too hot.
Mileage is "normal" at about 19-19.5 mpg average.
No smoke unless I am "cleaning the DPF."

Will post more if I can remember more. Will also try to get a video when I can. Starting a busy part of the week so it may be a couple of days.

JT

I've noticed something similar. My guess was it was when i had the Cruise control engaged, and the truck was just topping a hill or semi. Just as the CC is backing off the power due to the truck speeding up, and right before it starts reducing fuel to keep the set speed - that's when i get a littlepause/ hesitation in the momentum. Like a wind buffet. Once i pass the semi, or get to the bottom of the hill, everything is back to normal...