Greetings all,

I have a 1997 F350 PSD 4wd automatic with 4:10 axles ratios with auto front hubs and 134,000 miles. I have stock aluminum wheels and BFG AT tires. I have developed a new (or increased vibration) above the speed of about 52 miles an hour.

The vibration is felt in the steering wheel and in my feet but not in my butt. It sort of sounds like the noise my previous trucks have made when the front hubs were locked (this truck has never made that noise).

The vibration, maybe growl is a better term, occurs when holding speed or increasing speed but not when I let off the accelerator. The growl can be slightly increased when a move the steering wheel out of the neutral position. I don't know if this is because there is more positive connection between the linkages up to the steering wheel or if it is actually contributing to the condition that makes the growl.

I thought it might be rear driveline U joints but they (2) were replaced by the dealership about 12,000 miles ago. Then I thought it might be the front driveline U joints. Thinking that my auto hubs might not be unlocking I jacked the front end up and checked each side. They seem to be fine. When I spin the front wheels the U joint at the axle ends did not rotate which tells me the hubs or disengaging properly meaning it can't be my front driveline U joints making the noise.

One other noise I have noticed at the same time is a sharper vibration at idle. It is not necessarily louder, it is just sharper to the point where other parts of the hood/cab of the truck seem to be making noise now.

What finally tells me something is different is that my feet are tingly after an hour of highway driving. That I know for sure that this is something new.

Does anybody know what could be causing this? I can't think of what it could be.

TIA,
Blane

 

sounds like it might be a bearing problem ,front wheel bearings wearing out, are the tires on the front worn uneven high spots low spots were tread meets the rd or choppy wear ,
out of balance wheels ,bad shocks causes this wear , the tires bounce as they go down the rd putting extra strain on wheel bearings, causing wear , vibration
it will feel ok going straight soon as you steer the wheel one way or another you hear and feel rrrrrrrrrr in your front end
not saying that's the problem but a place to start

 

if you do take a peek at front wheel bearings ,or have someone else do it and they show signs of bluing, pitting ,scored, detents worn into race were roller rides , replace all rollers and races as a set cause they are worn out, and your life is worth the extra bucks

 

87cv,

Thanks for the reply. Early on I thought it might be the hub bearings but ruled them out for various reasons. I read your post and ruled them back in again, until I did more testing. I have done all kinds of tests and driving scenarios and without going into a lengthy reasoning have determined that it is not drive train related, it is engine vibration/noise. This may also tie into the sharper vibration I get at idle.

The only thing I can think that has changed in the engine is possibly the harmonic balancer. I have not had time to investigate the archives but I am wondering if anybody has a simple test/observation that could tell me if my balancer is no longer good.

Thanks again,
Blane

 

I have a engine vibration at around 2500 rpms, its my air pump getting ready to let loose. Might be some thing to think about with your engine vibration

 

86,

Thanks for the reply. I am not familiar with an air pump on these engines. Do you mean the turbo charger?

Thanks,
Blane

 

In my 05 excursion 4x4 v10 I have the same issue I think. Dull roaring reverberating howl while cruising at low load. No load it starts at around 2800 RPM. Have you figured out your issue?

 

This may not be the case on a 4x4 but try making a hard lane change,SAFELY!, at speed left and right so you're loading the bearings. A left lane change would load weight onto the right side and a right lane change would load the left side. Listen and look for the vibration you speak of when your doing this. If you hear or feel something to the left you have a bearing issue on the right side and vis versa. It works well on a car or light truck with rear wheel drive.

 

Yes, I found my problem months later. I should have updated the thread.

I found that when the transmission shop put my transmission back in from a rebuild they did, a clamp on the muffler had been rotated and the end of the threaded portion would touch the transmission when the engine was under load and after it had warmed up. I cut off a portion of the threaded part and rotated the clamp and the noise went away.

Blane

 

Wow really? a clamp huh. I think mine is either the harmonic balancer or an issue with either my flex plate or Torque converter. Last things I can think of unless it's my oil pump. I have never heard an oil pump making that noise.