Not-Mechanic

I have a 2003 4Runner Limited 4WD with about 85K miles. Intermittently I will feel a vibration that I can best describe like driving over a corrugated road(like a tractor tread has cut a pattern in the asphalt.) It happens for a few seconds and then goes away. I have not been using the 4WD features, I just put it in Drive. I have not had to do anything at all except change fluids, tire rotations and balances, and replace tires. I do know that there are places in these mountains here that do have roads like this, and for awhile I was chalking it up to rural conditions, but lately it seems that it happens in places that it didn't before. I'm a woman in my late 50's and take care of my invalid aunt in her late 80's. Without my truck we are in a real fix. I am not mechanically savvy, and I don't want to get ripped off when I take it to the mechanic to be checked. Anyone who can advise me on what might be the cause, any road tests I can do myself to narrow the problem down and better describe it are sought with great gratitude.

rokblok

iTrader: (1)

May we inquire where you are at? At least a geographical area, since one or more of us may live nearby, and be willing to lend an ear/hand.

Its hard for me to say, maybe someone else can have more input, but if it happens on all road types, at all speeds, it could be that a tire is seperated internally, a wheel could be loose(wheel bearings or lug nuts), or a number of possibilities. Its really best for an experienced ear to feel/hear this...

Not-Mechanic

I am in the Catskill Mtns in New York. I drive mainly on Route 28, which does have some bumpy sections, but it also happens on other roads, and at different speeds. My Aunt says that there are spots in the roads that do this, so I am going to pull off the road the next time it happens, and walk back and take a good look at the surface.

Thanks for the input you have given so far, it does give me a place to start. The tires are pretty new, I purchased them for my move across country about 10 months ago. I will check the lug nuts and all the tires to start. I really wish I knew more about my truck's mechanical functioning, but now is as good a time as any to learn. It has been so darned dependable, before moving I used to take my delightful 4Runner out into the California desert to get away from big city life, now I am in a tiny hamlet with 200 residents, far from any big city. Here winter can last five months and bring 7 feet of snow, thank goodness for 4WD. Also, I know that before the winter arrives and they salt the roads I need to get an undercoat applied to the undercarriage. Do you have any suggestions?

rokblok

iTrader: (1)

The vibration could be caused by a number of things. A pothole hit with a bad shock can allow the wheel tire to continue to bounce(shocks prevent continuous bouncing). A tire out of round(seperated) can vibrate from centrifugal force throwing it out. A loose set of lugs can cause a wobble at any time, but usually all the time. Loose wheel bearing can cause the same symptoms. Bad ball joints or tie rods(steering) can create this scenario. If in your realm of expertise, maybe jack up a corner of the vehicle and see if there is any movement in the wheel. grab the tire at 12 and 6 o'clock and try and move it. Do the same at 3 and 9 o'clock and if there is movement anywhere, try and locate it. Or also visibly inspect your tires, on the outside sidewall, and the inside sidewall as well, for any "bubbles" or seperation of tread or rubber.

In regards to an undercoating to protect against salt corrosion, after the vehicle has been on the road a while, its hard to prevent corrosion with an aftermarket coating. There is a good possibility of having some corrosive agent(salt) somewhere hiding, and then having it covered by some undercoating would cause even worse corrosion. Its really your call, but washing it off at the car wash regularly, especially the underside, would help greatly.

Not-Mechanic

Than you so muck Rokblok. I do know how to use a jack, change a tire, change oil, keep my fluids clean, etc - when I had a '63 Falcon Station wagon I could change the plugs, set the timing, adjust the tie rods, etc, but that was a different century and I was younger and braver...My 2003 4Runner is half computer, that takes more skills, and there is so much smog stuff you can hardly see the block...I will do the things you have suggested, and I really appreciate your advice about the undercoat. I'll take it down to the self-clean car wash again, that is what I thought best, and it's cheaper! I love this truck, it will probably outlive me...
all my best, Lyza the not-Mechanic