This happened quite a while ago, but I'm still dealing with it. About 2 years ago, I had an accident while I was engaged in 4WD hi. I hydroplaned and hit the middle divider on the highway. It bent my left wheel inward, cracking my caliper, breaking my rotor in two, damaged control arm, and bent my rear axle. I replaced those parts and the truck runs fine, wheel alignments come out perfect, no engine damage. The 4WD works fine, however, when I take it out of 4WD I hear a grnding sound coming from the left drivers side. There is nothing rubbing because after a week driving, it goes away. This happens all the time. Also, it only happens when I cruise under 50mph. It sounds like gears grinding, a pulsating grind that is goes from soft to loud every couple of seconds. The best way to describe the sound is that it is like the sound of the tires when you go over a bridge with the metal ridges on the road, usually drawbridges have this. Any ideas on what I should have checked out/repaired, or what might be broken? Thanks in advance.

 

Maybe your auto-locking hubs, just a guess though.

 

What side is your steering wheel on? The left is the driver side, the right is the passenger side... You probally have some issues with the ADD fork not disengaging correctly.

 

Sorry Andy, that was an error, I fixed it though. Just to give some more info, I have a 98 4Runner SR5 4WD. What are the ADD fork or auto-locking hubs, and how would I test to see if that is the problem?

 

More than likely, that will be a dealer fix. sorry.

 

I don't want the stealership to fix it because I had them replace my timing belt, and they screwed up my radiator. Plus they charge you up the @$$. A regular mechanic can fix it right? Is there a diagram anywhere of the 4wd unit that I can get?

 

Not really. The ADD forks are sometimes tricky to get properly aligned from what I've read. I had NTB change out a CV shaft (passenger side) when I bought my 4runner and they pulled the flange and had a local axle shop rebuild the joints, then they reinstalled the fange and shaft. Well, they didn't do it right, and I had no power at the wheels in Awd with the center open diff unlocked. This meant the axle was not properly engaging. Instead of taking it apart and ~trying~ to fix it or even calling the axle shop for advise, they instead sent me to the dealer and paid them to fix it. They didn't want to touch it. Apparently, they had some issues with it when they put it back together and didn't bother to tell me. Maybe somebody like Schaeffer will pipe in on this one. He has much more experience with the front ADD system.

 

What is the ADD fork?

 

they're what actually engage and disengage the axles from the front differential when you put it into and take it out of 4wd.

 

Well, I'll take it to a mechanic that my father knows to see if he can diagnos the problem. If it is that, then I might take it to the stealer if he can't fix it. Thanks. Can it be a bent axle?

 

Have you ever tried jacking up your left front, removing the wheel, and then engaging/disengaging your 4wd?

 

No. I might try that this weekend. Should I do it with the car on?

 

If you have ADD your engine needs to be running for it to function correctly.

 

Have you found out anything on this problem? The same thing recently began happening to my 99 after an especially hard wheeling trip....