I have a 98 4runner 4x4 (manual) V6, auto tranny, with no mods. When i left the house the other day heading for the highway I disengaged the 4wd as i was leaving the house (no reverse) when it was cold...-20C or so. Everything seemed fine until i hit the highway 5-7 minutes later and accelerated to highway speed. It felt like something in the drivetrain was slipping, possibly the transmission and I could hear a "clicking" noise near the front end of the vehicle. It also seemed like it took a little longer than usual to shift. It did it again 10 mins later when i had to accelerate again. When I got to my destination a few minutes later, I tried engaging/disengaging the 4wd a few times while going forward in areverse for a few yards each time. Everything seemed to be normal after that. After discussing it with a mechanic i work with, he suggested that the front hubs may not have been disengaged. Does this make sense? Would it feel like the entire drivetrain is slipping if this is the case? I haven't replaced the tranny, diff or transfer case fluids in ages so I was getting a little worried that something big may be screwed. I plan on getting it done in the next week or so.

 

98 4Runners don't have front hubs, unless you've added some. It's possible the ADD didn't disengage but I don't see how that could cause slippage. It would cause drivetrain binding though, especially if the roads were bare.

 

No, I haven't added hubs. Just the stock front-end. What does ADD stand for? It really felt like something was slipping, but maybe the motor just had to work a little harded to push the binding and as a result shifter at a higher RPM than normal??? Could there be something not fully disengaged in the tranfer case that could give me a slipping feeling with a bit of a knocking noise? Like I said, it seemed to stop after i messed around with the 4wd lever a few times at slow speed.

 

ADD is Automatic Disconnecting Differential. It uses a sliding sleeve on one of the side shafts to disconnect one of the front axles, the other one stays connected. The sleeve is vacuum controlled, it's possible your's got stuck, maybe from the cold.
There are no front hubs needed with this so the front axles are always turning. Some people swap in manual hubs to completely disconnect the axles shafts, this reduces wear on the Cv joints, especially with a lift.
Here's some more info
http://toyota.off-road.com/toyota/ar....jsp?id=399612

 

Sounds like automatic tranny trouble to me. It could be low on fluid or it could be a plugged screen or a host of other things in the trans. In my experiances most troubles with auto trans. are more noticeable when cold. Take it to a transmision shop and let them drive it, or better yet let your mechanic friend try it when it's cold (free opinions are nice) Most shops will give free estimates on things like this. Gool luck

Hal

 

Just checked the tranny fluid...the color and smell seems ok.