joestox

Hey all - let me try to describe my issue:

I've got a 1994 4Runner 3VZE A/T 4WD. Full disclosure I have a blown head gasket and at least 2 cylinders are compromised (maybe more?). I am planning to fix this very soon. But mentioning this because my engine does have low power and maybe that is part of the issue.

For about a month and a half - when starting from a dead stop the 4Runner would kind of do a few odd lurches forward when I put my foot on the throttle to get started. I suspected maybe the clutch in the automatic transmission was starting to slip but it wasn't so bad yet so I pretty much just lived with it. Now during this time I regret to admit that my automatic transmission fluid was way too high in the transmission. Basically when looking at the dipstick it was in the "hot" zone when the engine was cold.

A few days ago the lurching got real bad. In fact I am now having trouble even starting from a dead stop. Here are some of my observations so far.

• Cold start and the car behaves as it had for the past month and a half (aka I can drive around just fine)
• When the engine is hot
  • L4 seems to work fine
    • However when performing a sharp turn at low speeds in L4 it seems as if the back tires lock up ever so slightly (brake shoes locking up? I don't see evidence of any leaks back there)
  • H4 and H2 are the ones having the following problems.
  • 75% of the time
    • If the car is pointed uphill at a slight incline and the shifter is in Drive it is real hard to get the car to move forward now. The engine will rev to 4k and still nothing.
    • If the car is pointed downhill, the car will start to move forward in Drive and I can get the car to respond to my foot on the throttle but the lurching is pretty bad.
    • Shifter in Reverse has the same issue as Drive when trying to go reverse with the car pointed downhill on a slight decline. The engine will rev to 4k and still nothing.
    • Shifter in Reverse with foot off the pedal and car pointed downhill and the car starts to roll forward as if in neutral.
    • Shifter in Drive with foot off the pedal and the car pointed uphill and the car starts to roll backwards as if in neutral
  • Here is what happens the other 25% of the time
    • Sometimes I can get Drive and Reverse to work. But in each case the lurching is quite bad. Is this lurching maybe more evidence of the rear brake shoes locking up?
  • If I can get the car to move and get to faster speeds the car behaves normally

Here are some key observations.

• The issue is most (only?) apparent when the engine is hot
• I can get the car to behave as if its in Drive or Reverse from dead stop but only about 25% of the time
• Sometimes the car acts as if its in neutral when its actually in Drive or Reverse
• L4 seems unaffected

Hypotheses of mine so far:

• Transmission has issues
  • slipping clutch?
  • seems like its just 1st gear and reverse having issues in H4 and H2 so maybe something specific there?
  • solonoids?
  • clogged filter?
• Head gasket is much worse than I thought and the combination of locked up brake shoes and low engine power result in the "lurching" I am experiencing when starting from a dead start

Open questions:

• Why does the operating temperature seem to matter?
• What is the lurching
  
  
  Some updates after reading other posts:
• I fixed the transmission fluid levels - its now correct
• The fluid was not a "pink milkshake" it was reddish/brown
• There is a whining noise coming from under the vehicle when the engine is on

joestox

Some updates after reading other posts:

• I fixed the transmission fluid levels - its now correct
• The fluid was not a "pink milkshake" it was reddish/brown

Wiggarigg

I had this same issue. There's some sort of reset adjustment you can do by getting it to operating temperature then backing up 15-20 feet. That would get mine to catch right for a while. I had all gears in 4L with smooth shifts, but nothing in 2H or 4H. So more of a transfer case issue than a transmission issue. Theres a solenoid in the transmission that handles that duty. I figured if I was going to drop the pan I would just replace all of the solenoids. 3 of them, I believe. You can get them as a set online for a fair price. Might as well clean the tranny filter while you're in there. If it's an oem original filter with the fine mesh screen instead of filter paper, just take it out and clean it with brake cleaner. Like a can or two. Toyota does not recommend changing this filter with aftermarket crap. It's designed to be cleaned and reused. I did these things and it's been golden since. But I had awesome head gaskets at the time. Lol

Wiggarigg

Also I would refrain from the lurching as much as possible. Just because. You don't wanna eff things up in there. The brownish color in your tranny fluid means it's gotten hot in the past. Dropping the pan will result in the displacement of 4 or 5 quarts of less than desirable fluid. When you put it all back together and put new fluid back in it'll thank you.
When you do your head gaskets plan on doing some exhaust work and get rid of that damn crossover pipe between the engine and firewall. Some people will say that contributes to the head gasket issues on the 3.0. Some will say it doesn't. If it's your back cylinders that are affected you can make your own decision about that. Either way cross it under after you put some headers on that puppy. Nobody needs that much extra heat under the hood.