hey guys, my 88 4runner has developed a vibration and noise while at highway speeds. The vibration starts at about 50mph and gets worse up the faster it goes. it doesnt sound rotational like a out of balance wheel or brakes or bearings. the noise and vibration are on a 5 second cycle of light hum intensifying to rattle the whole truck then subsiding again. does this sound like an out of balance drive shaft? rear end maybe?

 

Driving in 4wd? Ice build up on the rims? Bad Ujoint? Those would be the most likely.

 

I'd check there first.....Check all your U-joints and make sure all the snap rings/clips are in firstly. Give your drive shaft and quit tug back and forth see if its shifting in any direction.

I had a 91 Ford Ranger that had the same issue, only did it at 50mph and higher speeds.

I was doing 70mph down the Interstate and the rear U-joint failed, as one of the caps came off due to a missing snap ring (thankfully it didn't drop or the front failed and dropped) and all hell broke loose lol. I was able to get it parked and towed without meeting my maker that day.

So yeah check the u-joints, drive shaft, and yokes. You don't ever want to come that close to soiling your jeans like I did that day.

Be easy.
D-

 

Thanks I will be sure to check those first thing. Could it be rear diff as I do have a small leak ? (already filled it) My 75 mile commute says it will break down 74 miles from home.

 

Where is it leaking from? Filler bolt? Or some wheres else? And does it lose a lot of fluid? I'd be careful with that as well, it can cause vibrations (very bad ones) if you are low on fluid. Then you run the risk of tearing up everything inside,which is the case most times.

Edit:: to remove a dumb question lol

 

Check the torque on the output shaft on the transfer case. They do wear and need to be tightened. There are some other threads on here about it. A little searching and you'll find them. Just a suggestion that fixed a vibration I had one time.

 

Check the companion flange. That was my vibration problem starting at about 150K.
https://www.yotatech.com/forums/f116...-flange-92457/

 

I would look at your U-Joints. I had the same problem a couple thousand miles ago.

 

If 2 or more tires have issues(toyotas are VERY sensitive to tire issues), they can phase in and out with each other causing a cyclic droning type noise that will typically go away around 75 mph+. The output bearing on the transfer can fail and cause a similar concern. To check, push upward on the driveshaft at the transfer and see if there is any movement. I also agree with everyone else-check your u-joints and make sure your hubs are un-locked

If the noise gets better or worse while accelerating or decelerating, it is not the tires. If the noise stays the same, it is more likely to be tires.

 

When checking the u-joints, sometimes you need to actually drop the driveshaft down and inspect it. Just shaking it back and forth while still mounted in place might not yield a valid result.

 

My 86 did that. Turned out the bolts for the rear driveshaft to the output flange of the transfer case had loosened. I was a dumb 17 year old kid at the time. And they worked out / broke off, and I dropped the front of the rear driveshaft on I-19 going 65 miles an hour. Was a bad day.

 

May offer a little help diagnosing your issue..

https://www.yotatech.com/forums/f116...s-help-244594/

 

thanks for the help. I finally got ma chance to do some work to my new rig this weekend. Changed the alt, dist cap and rotor, plugs and wires, ignition coil and fuel filter(all but plugs factory from 88). Checked the U joints and flange bolts. All looked good and tight, but didnt pull the driveshaft. The U joints were pretty dry so I hit everything with the grease gun, and that did help the vibration some. New U joints next weekend.