I am having an issue with my 93 4runner, 3.0, automatic tranny and auto hubs. At 60 and above I am getting a vibration from the front drive shaft and If i continue to 75 mph the vibration gets sightly worse then it starts blowing oil from the 4x4 output flange of the transfer case and over heats ( only the forward flange to the 4 wheel drive)
Should the transfer case even be spinning at these speeds when in H2? Could the solenoid be semi stuck in H4? Changed the seal and still leaks at 75. Its also slow to engage in L4 like pressure is slow to get there when in drive.
Should the transfer case even have a lot of pressure in it since it is just an oil bath for the case section?
Last tranny the case cracked in half, this one has a fresh rebuild, and case and is running great except for the transfer case oil seal issue.
Also is it normal in over drive at 65 to 70 mph to be at 3000 rpm or above. that is 700 rpm higher than my 2wheel drive Tacoma with the A340E tranny?

 

With ADD the front drive shaft always turns.

Something is unbalanced or about to fail .

Drive shaft or CV axles ??

As long as you have a vibration things are going to leak.

Is your vent perhaps plugged ??

If it is pressure will build in any gear box.

 

The CV joint and the u joint were all just rebuilt. New flange seals. the vent is clear, or at least when I had it out of the car and on it's side the fluid flowed really well on to my garage floor through the vent.
I could not mark the flange to shaft locations due to different trannys going in this vehicle, so it is possible that is the balance issue. I have been trying an old school trick to balance it buy putting a hose clamp on the shaft with a .25 oz weight and re positioning it until vibration goes away, and I have it down to a very slight vibration, but it could take forever to completely get rid of it. Problem is it blows fluid out the flange seal with out the shaft installed and no vibration. Funny thing is I can take out the seal and no fluid pours out and that part of the case is submerged in fluid, seems to me it should flood out of there with out the flange and seal.

 

I have to wonder is your transfer case screwed up and your driving around with it locked in 4High

Thinking your in 2wd This could be a real possibility .

The truck sure does not like going that fast on hard surface roads in 4wd.

Just how did you manage to break the case ??

 

I am checking out the vent but it seems ok, it does look like the fluid may be coming down from there and blowing everywhere.
On my last high speed run the tranny did set off the over heat light, so it could be related to heat expansion.
Like I said before it seems to run higher than normal rpm at highway speed (3200 at 65 mph in overdrive). Yet the overdrive clutch is set up at the minimum clearance set by Toyota. Having said that, I have noticed there is no up shift to overdrive for the first 3 min after starting the truck, then it shifts normally. I am thinking I may have a sticky lockup solenoid not allowing it to fully lock. Looking at changing the solenoids.
I am also looking at a trans cooler with a fan.
I have the drive shaft vibration to a minimum now, but still blows the fluid, funny there is no fluid loss until I hit 75 mph.
The question about how the case cracked is a mystery. I bought the 4runner as a basket case and was told everything was in working condition except the steering pump and alternator needed to be installed on the rebuilt motor.
Well the motor was locked solid, so after some investigation, I found he put in the engine with TC connected to the flex plate and pulled it together with the bolts. Then I had to pull the motor and found out the engine was taken apart, parts cleaned and painted and put back together finger tight. Then I checked the trany and found he had bent the flex plate and broke the gear in the pump. Also the first snap ring on the overdrive clutches were out of it's groove. I secured the snap ring and replaced the front pump. Then I rebuilt the engine and when everything was running I took it to get smog tested and when they ran it up to cruising speed the case cracked in half and dumped 10 quarts of fluid on their floor.
They were not impressed!!!
The tranny cracked all the way around that groove were the overdrive snap ring is, I never figured out why it cracked , but all the parts were new in the tranny, must have been the previous owners attempt at a rebuild.

 

P.S. I did check to see if it was in locked in H2 and it seemed to be, but I readjusted the position sensor and there was no change.
Also the vent lets air through, but it does not flow freely, it could be the pressure is not getting out fast enough and builds excess pressure and comes out in a burst with fluid. I have a new one coming.

 

Just to clarify: the front drive shaft (between the transfer case and the front diff) should not be spinning when in 2wd, assuming the ADD is working properly. The CV shafts spin all the time, but the spider gears take up all the motion in the diff and do not transfer it to the ring gear.

Your ADD could be stuck in the engaged position (due to a vacuum or electrical issue), or your xfer case could be stuck in 4hi. Since it's electronically controlled, you'll have to do some sleuthing to find out what's going on.

Your front drive shaft shouldn't vibrate even if it is spinning at 75mph. It should as smooth as the rear one. The vibration is probably causing your front xfer case seal to leak. I think you have several problems you need to track down.
- Why is the front drive shaft spinning in 2wd
- Why is it vibrating at speed
- Why is the front seal leaking

To troubleshoot the first issue, put the truck in 2wd in park with engine off. Reach under and try to turn the front drive shaft. It should turn freely.

If it doesn't, jack up both front wheels and spin one while holding the other. The CV shafts should turn with the corresponding wheel, but the drive shaft shouldn't turn. If the drive shaft turns, your ADD is stuck in the engaged position. If it doesn't, your transfer case is stuck in 4wd. If you can't turn one wheel while holding the other, both the ADD and 4wd are stuck engaged.

 

The shaft is defiantly spinning I have got most of the vibration out, now just a slight amount at 70 to 75.
What exactly is the ADD? Is that the electronic activation on the front dif? I did notice when I changed the cv's in the front the left on was engaged with the wheel and turned, but the drivers side was completely freewheeling. I don't know if this is normal.
I put on a new vent and air blows through it freely and the old one was restricted. Now I am not blowing fluid.
I am thinking that the lock up solenoid is not fully engaging or leaking, so I am going to put another on on. It just seems like a lot of RPM to be at 3500 RPM at 75 mph. Can't be very fuel efficient. The solenoid seems to stick when cold and won't upshift to overdrive until the tranny starts to warm up, then its fine.
If the previous owner worked on the diff it is most likely correct!

 

So do you have ADD (Automatic Differential Disconnect), or automatic hubs? My understanding is that all '93 4runners came with ADD. Here's more info on that.

ADD is a sliding collar on the driver's side of the front diff that is actuated by vacuum, that either locks the driver's side CV shaft to the diff output shaft, or unlocks the connection between them. When the connection is unlocked, the driver's side CV shaft just spins with the wheel, independently of the diff. The passenger side still drives the internals of the diff, but the friction in the spider gears in the diff is so low that nothing else turns. The ring gear, pinion, and drive shaft should remain stationary.

If the ADD is unlocked, the driver's side CV should be disconnected from the diff. It should always be connected to the driver's side wheel. If it isn't, you have issues in the hub.

There are two vacuum solenoids in the engine compartment on top of the passenger side fender. These are switched when you move the transfer case lever between 2wd and 4wd. They route vacuum to the appropriate side of the ADD sliding collar actuator, such that the CV shaft is unlocked in 2wd and locked to the diff in 4wd. There is a relay under the dash that is actuated from the transfer case switch, that provides proper power to the vacuum solenoids. If the engine is off, with the ignition switch on, you should hear the relay click when you move the t-case lever. If you raise the hood and listen by the passenger fender, you should hear the vacuum solenoids click when someone moves the lever.

You can pull off the vacuum lines from the ADD actuator by the differential, start the engine, and feel for which one has vacuum. When the tcase lever is moved from 2wd to 4wd, the vacuum should shift to the other vacuum line.

The most common failure mode for the ADD is broken or disconnected vacuum lines.

 

Well I checked the solenoids the ports change when shifter is moved to h2 &L4. pulled the actuator off the diff and tested it and it is working fine, but I disconnected the vacuum and reinstalled it in the disengaged position then went for a 75 mph run and it is still vibrating from 70 to 75, but good under that.The vacuum is real low from the canister, but it may be the way they are, the valve switches with very little effort so it doesn't need much to switch.
I am beginning to think the vibration may be coming from the rear drive shaft, or a bad bearing in one of the diffs. I am going to remove the front shaft and see if the vibration still comes in.
I still don't know why the forward shaft spins in 2w drive. I do know the shaft spun with all three trannys it has had in it, but I did not get a vibration from the other trannys.
Good news is, it still is not shooting fluid now.
I also noticed I did not use the original flange for the rear shaft. I did find the original flange and it still has my position mark on it, so I will change it back if I find it is the rear shaft.
I also can't understand why I can reduce the vibration at lower speed just by adding weight to the forward shaft and moving the weight in different positions on the shaft when the diff is not engaged. It must have something to do with the transfer case being married to the main tranny shaft. The clutches still move and cause resistance which I would think would turn the chain that turns the shaft, but it should not be enough the turn the shaft very fast, those clutches have a lot of clearance, about .100 thousands, spec tolerance is between .0900 and .1200 . I'm Feeling like I am beating a dead horse! There seems to always be something with this 4 runner. I have rebuilt literally every functional part in the truck, over three thousand dollars in parts and a year of my time and I still cannot run it on the freeway over 65mph. About to run it off a cliff soon!If I spend to much more my wife will make sure I'm in it when it goes over the cliff. I have over 40 years experience as an auto and aircraft mechanic and this one is kicking my butt! Might have to put a chevy drivetrain in! LOL

 

Your overdrive issue is normal on these trucks. My 4runner will not shift into overdrive/lockup until engine is a norm operating temp. Why Toyota did this beats me but its how they are.

 

Tested with the forward shaft off the car and vibration is still there, so I replaced the flange at the tranny with the original and it is much smoother with no vibration at all at lower speeds and now a vibration comes in at 75 mph. I am going to try a movable weight on main shaft like I did on the front shaft.
I did find on the forward shaft one of the CV u joints was to tight and would not move in one direction, that is why it vibrated after installing the shaft. I will replace it tomorrow.
I am thinking this last bit of vibration could as well be in the pinion bearing or tranny output bearing because the shaft feels balanced under 70.
Oh, while testing my speedometer is now not working. I hear that is another of the Toyota issues.