For a while my 2004 Hyundai SantaFe has a vibration that happens at highway speeds when the gas is applied. It tends to be less when the gas pedal is released. I have had the tires balanced, an alignment, and took it to the dealer to check the CV joints, struts and such but it still vibrated. The dealer said it was probably the tires. So, I took it back to the tire place and wound up getting a new set of tires. No luck - it still vibrates. I need to find out what else it could be. Anybody have ideas?
Can you be more specific? Your title says “rattling” which is not necessarily the same as “vibration.” Is it a sound like rattling sheet metal? Or a vibration you can feel through the steering wheel? Can you hear it at all? Or only feel it?
Where’s it comming from ? Front , back , up, down, side ?
Years ago my hiway speed rattle turned out to be the …door handles ! ( air flow at speed )
The tension spring didn’t hold down tight enough but with a little adjustment inside where the handle clips to the actuator rod, the rattle was stopped.
It is a vibration felt through the steering wheel. It increases with acceleration. It even happens after new tires. Comes from underneath. It feels like going over a rumble strip with small ridges.
Have a front-end specialist check the ball joints and tie rod ends, a.s.a.p.
If they are severely worn, as I suspect, this is a significant safety issue.
Or, at least it is a significant safety issue to people like me who don’t want a wheel falling off, or who don’t want their steering to stop responding when they turn the wheel.
In all seriousness…this has the potential to be something serious in terms of vehicle safety, so you need to have somebody who is really competent check the suspension and steering components for excess wear.
If the ball joints & tie rod ends turn out to be okay, then my next suspect would be the inner CV joints. More than likely, only the outer CV joints were checked at the dealership.
Since it gets better when releasing the gas pedal, my first suspect would be some kind of a CV joint problem. If the dealer hasn’t already inspected all four of the CV joints, that would be the next step. Sometimes the car needs to be put on a lift and run in gear. Don’t try this yourself, as it can damage the differential in some cars unless it is done correctly.
Try a dose of sea foam or techron. it could be a partialy clogged injector. An engine misfire has often been misdiagnosed as a suspension problem.
I recently had the same problem on a different front engine auto. Check the motor mounts. Accelerating lifts the engine and results in vibrations getting off the gas lets the engine back down and the vibration is gone. Good Luck
Turned out to be the CV shafts. They were changed this past Friday and the vibration is gone.