Sorry for the long post, but I wanted everyone to have complete info.

After searching, this seems to be a pretty common issue, with variances in the causes and effects. I have had this problem develop over the past few months, so it isnt something that has always been going on.

Here is what I have observed:

It is a high-speed vibration and audible resonation of sound through the cabin. It occurs between 50-70 moderately, and anywhere over 80 it gets much worse. It is most noticeable accelerating up a hill and when decelerating or letting off the pedal at those speeds. The vibration rattles the dash, mirrors, and any loose change around. I can't feel any vibration on the transmission shifter. It can be felt on the transfer case shifter, but I have always been able to feel vibration there. It can be felt through the floor pan of the drivers seat.

Specs:

1998 3.4l Runner
117,000 miles
Automatic

I have owned this truck for about a year and a half. It had one owner prior to me, and he seems to have taken pretty good care of it. I have most of his service records. No major work done. A few events occured almost simultaneously, so I dont know if one or the other could be the cause of my problem.

-Had one side of rear axle seals replaced. This was a pretty bad leak, and the pumpkin was pretty dry I think by the time I got it somewhere. Thanks to the salt treatments up north, the diff fill plug was rusted in to the point that I couldnt get it out to fill. Other sides seals were replaced last Octoer. They put in synthetic gear oil.

-The very next day, I had the dreaded ATF cooler in the radiator burst and make a milkshake in my tranny. It took me about 3 weeks to get this taken care of. The tranny shifts as smoothly as it ever has, and I notice no difference in its operation. New radiator was put in of course.

-Tires were rotated recently with no change.
-Alignment done yesterday with no change. They did say my ball joints were in bad shape. Once again, thanks to the salt.

-Tires are in good shape. They are a Bridgestone Duelers, so no aggressive mudders or anything that should produce this type of noise/vibration.

-My mom backed into my car's front end during this time and toasted my bumper and bent the drivers fender in a little. She drive a 3/4 ton truck, so of course there wasnt a scrath on her truck. This was just fixed this week, but the damage was all body. I have somewhat ruled this out as a cause.

So I did say that I searched and read, so here is my plan of action for the weekend:

1a. Check ujoints. I crawled under there in the past few weeks. There is no play in the rear shaft, up, down, or turning. I have fooled with u-joints before on my (gasp) Jeeps and Samurais, so if I get ambitious, I might just pull the whole shaft off out.

1b. If I do the above, I can put it in 4hi, I understand, and give it a drive around. Is this safe at highway speeds though?

2. Jack up the front and get a good shake on each tire to check the bearings.

3. Get wheels balanced. Two of the wheels are about a year old and were bought new.


That is about as far as I can think ahead. Is there anything else I need to be looking for/doing?? I commute on the interstate 50 miles one way each day, so this is a very annoying problem.

Any help is greatly appreciated.

Daniel S.

 

Find someone with rims/tires and swap. Still the same it aint the tires.

My guess is rear d-shaft u-joints or bad rear diff from running low on gear oil.

 

I saw that you did rear wheel seals what about bearings??? I had a rumbling and another noise for a while and replaced the right rear wheel bearing and now just the rumbling which I think is the carrier bearing. so I would say wheel bearings or rear diff. and would bet if you did what you should and replace the rear axle altogether it will disappear. when you install the new rear axle either lock tight or anti-cease the fill and drain plugs "and make sure you paint the fill and drain plugs!!"

 

Honestly I didnt know when the seals were replaced that the bearings should be too. The shop did not note that anything was wrong with them either. Are you saying that I should replace the entire rear axle? What do you mean by paint the drain plugs?

 

Sounds like rear driveshaft to me - I have the same bad vibration in my '85 with the lift on due to the rear pinion angle.

You don't need a whole new rear axle.

If the rear driveshaft has been removed or messed with at all you might check and make sure it's in phase.
Do a search on here for it and you should find a link to Roger Brown's (4Crawler) site where he explains it all.

You could also find a local driveshaft shop and have them drive it and see what they think - often times little places like that will give you a guesstimate free of charge.

Fink

 

you did say that the fill plug was rusted in. so I am going to guess that the drain plug is as well. If you can not get the plugs out then yes replace the whole rear axle. this way you have a new pumpkin aka 3rd and bearings.
There are two seals on each side the inner and outer. I don't believe that the outer can be done with out replacing the bearing due to the retainer. The retainer must be heated to be pressed out after this it is no longer any good.
Our trucks are very good at rumbling for thousands of miles due to bad bearings.

The reason I say to replace the whole thing is at a junk yard you can get a good one for between $500-1200 depending on the model.



Frozen plugs are a pain to replace but possible so if you are so inclined then you can go this route first.
The 3rd is not cheap and the whole axle is going to run around the same to a couple hundred more and you will end up spending that on bearings and seals. So I am in favor of finding a wrecking yard with the whole rear end and just swapping them out.

and painting the fill/drain plug when you re-install is going to stop them from rusting and anti-cease or lock tight will prevent the threads from freezing. I would anti-cease and torque then paint!

 

I think the shop was able to free the fill and drain plugs when they did the work. I specifically asked about them, so I would hope they would not plain lie to me. I'll have to check on them though I guess.

As far as the problem goes. I popped out the rear driveshaft over the weekend. Got the ujoint out, and the spindle bearing under one of the caps were non-existent. I wish I had pictures. There was nothing but dried powder that I assume was the remains of the bearings. Got a new one in. The vibration and noise is almost entirely gone. I might look into another thing or two, but this is nearly a 100% improvement. Good call on the u-joint guys! Thanks again!

 

Glad you got it fixed man.



Fink

 

which u-joint? I have a very similar issue, so I was just curious.

 

if your gonna do u-joints, you might as well do them both, cause then you know its gonna last another forever and then when you know ones going bad you know its time to replace the other too.

 

Yes. Replace all the u-joints in a drive shaft not just one.

Glad you got it fixed.

 

Not sure about other model 4runners, but my 1998 has a double cardigan joint at the transfer case side. Correct me if I am wrong, but that is not a serviceable part. So, there was only one for me to replace on the rear. I didnt do the front shaft joints.